Bird 7-9120 Multicoupler

YOU'RE HEARD, LOUD AND CLEAR.

8625 Industrial Parkway, Angola, NY 14006 Tel: 716-549-4700 Fax: 716-549-4772 [email protected] www.bird-technologies.com

Installation and Operation Manual forT-Pass® Transmit Multicouplers73-67-11 Series, 73-67-18 Series,73-67-25/25 (High Power) Series

Manual Part Number

7-9120

Warranty

This warranty applies for five years from shipping date.

TX RX Systems Inc. warrants its products to be free from defect in material and workmanship at the time of shipment.Our obligation under warranty is limited to replacement or repair, at our option, of any such products that shall havebeen defective at the time of manufacture. TX RX Systems Inc. reserves the right to replace with merchandise ofequal performance although not identical in every way to that originally sold. TX RX Systems Inc. is not liable for dam-age caused by lightning or other natural disasters. No product will be accepted for repair or replacement without ourprior written approval. The purchaser must prepay all shipping charges on returned products. TX RX Systems Inc.shall in no event be liable for consequential damages, installation costs or expense of any nature resulting from thepurchase or use of products, whether or not they are used in accordance with instructions. This warranty is in lieu of allother warranties, either expressed or implied, including any implied warranty or merchantability of fitness. No repre-sentative is authorized to assume for TX RX Systems Inc. any other liability or warranty than set forth above in con-nection with our products or services.

TERMS AND CONDITIONS OF SALE PRICES AND TERMS:Prices are FOB seller’s plant in Angola, NY domestic packaging only, and are subject to change without notice. Fed-eral, State and local sales or excise taxes are not included in prices. When Net 30 terms are applicable, payment isdue within 30 days of invoice date. All orders are subject to a $100.00 net minimum.

QUOTATIONS:Only written quotations are valid.

ACCEPTANCE OF ORDERS:Acceptance of orders is valid only when so acknowledged in writing by the seller.

SHIPPING:Unless otherwise agreed at the time the order is placed, seller reserves the right to make partial shipments for whichpayment shall be made in accordance with seller’s stated terms. Shipments are made with transportation charges col-lect unless otherwise specified by the buyer. Seller’s best judgement will be used in routing, except that buyer’s routingis used where practicable. The seller is not responsible for selection of most economical or timeliest routing.

CLAIMS:All claims for damage or loss in transit must be made promptly by the buyer against the carrier. All claims for shortagesmust be made within 30 days after date of shipment of material from the seller’s plant.

SPECIFICATION CHANGES OR MODIFICATIONS:All designs and specifications of seller’s products are subject to change without notice provided the changes or modifi-cations do not affect performance.

RETURN MATERIAL:Product or material may be returned for credit only after written authorization from the seller, as to which seller shallhave sole discretion. In the event of such authorization, credit given shall not exceed 80 percent of the original pur-chase. In no case will Seller authorize return of material more than 90 days after shipment from Seller’s plant. Creditfor returned material is issued by the Seller only to the original purchaser.

ORDER CANCELLATION OR ALTERATION:Cancellation or alteration of acknowledged orders by the buyer will be accepted only on terms that protect the selleragainst loss.

NON WARRANTY REPAIRS AND RETURN WORK:Consult seller’s plant for pricing. Buyer must prepay all transportation charges to seller’s plant. Standard shipping pol-icy set forth above shall apply with respect to return shipment from TX RX Systems Inc. to buyer.

DISCLAIMER Product part numbering in photographs and drawings is accurate at time of printing. Part number labels on TX RXproducts supersede part numbers given within this manual. Information is subject to change without notice.

Bird Technologies Group TX RX Systems Inc.

Symbols Commonly Used

NOTE

ESD Elecrostatic Discharge

Hot Surface

Electrical Shock Hazard

Important Information

CAUTION or ATTENTION

High Voltage

Use Safety Glasses

WARNING


Manual Part Number 7-9120Copyright © 2006 TX RX Systems, Inc.

First Printing: April 1994

Version Number Version Date

1 04/01/94

2 08/02/94

3 03/27/96

4 11/30/06

Table of Contents

Section 1General Description ...........................................................................................1Unpacking ............................................................................................................ 6Installation Overview...........................................................................................6 RF Cables and Connectors ................................................................................. 6 Intermodulation Considerations........................................................................... 6 General Installation Procedure ............................................................................ 7Transmitter Combiner Checkout........................................................................ 7 Required Equipment............................................................................................ 7 Procedure .......................................................................................................... 7 Measurement Accuracy..................................................................................... 7General Tuning Information ............................................................................... 8 Tuning Specifics .................................................................................................. 9 Fine Cavity Tuning............................................................................................. 9 Procedure ........................................................................................................ 9 Cavity Tuning Tip...........................................................................................10 Coarse Cavity Tuning ......................................................................................10 Procedure ......................................................................................................11 Retuning System to all new Frequencies ..........................................................12 Combiner Expansion .........................................................................................12 Typical Expansion Channel Installation.............................................................12 Peg Rack Procedure .......................................................................................12 Relay Rack Procedure.....................................................................................13 Setting Cavity Insertion Loss .............................................................................15 Cavity Loss Setting Procedure 1 .......................................................................15 Required Test Equipment................................................................................15 Procedure for T-Pass Loop .............................................................................16 Procedure for BandPass Loop ........................................................................18 Cavity Loss Setting Procedure 2 .......................................................................19 Required Test Equipment................................................................................19 Procedure for T-Pass Loop .............................................................................20 Procedure for BandPass Loop ........................................................................21Isolators..............................................................................................................22 Single Section Isolators .....................................................................................23 Tuning..............................................................................................................23 Required Equipment......................................................................................23 Tuning Procedure ..........................................................................................24 Dual Section Isolators........................................................................................25 Tuning..............................................................................................................25 Required Equipment......................................................................................26 Tuning Procedure ..........................................................................................27Maintenance.......................................................................................................29

Figures and TablesFigure 1: Block diagram of typical system ............................................................ 1Figure 2: Noise suppression graph for 6.625” cavities .......................................... 2Figure 3: Noise suppression graph for 8” cavities ................................................. 3

Table of Contents Manual 7-9120-4 11/30/06

Figure 4: Noise suppression graph for 10” cavities ............................................... 4Figure 5: Typical Peg rack model .......................................................................... 5Figure 6: Typical 19” Relay rack model .................................................................5Figure 7: Typical combiner installation .................................................................. 6Figure 8: Measuring T-Pass channel performance ............................................... 8Figure 9: T-Pass cavity fine tuning ........................................................................ 9Figure 10: T-Pass cavity tuning controls .............................................................10Figure 11: Coarse tuning a T-Pass cavity ...........................................................11Figure 12: Peg rack mounting details ..................................................................13Figure 13: Relay rack mounting details ...............................................................14Figure 14: Top view of T-Pass cavity ..................................................................15Figure 15: Setting loop adjustment reference......................................................17Figure 16: Setting T-Pass loop using step attenuators........................................18Figure 17: Setting BandPass loop using step attenuators...................................19Figure 18: Setting T-Pass loop insertion loss ......................................................20Figure 19: Setting Bandpass loop insertion loss .................................................22Figure 20: Single section isolator ........................................................................23Figure 21: Mounting layout for single section isolator .........................................23Figure 22: Connection of return loss bridge ........................................................24Figure 23: Tuning single section isolator step 2 .................................................24Figure 24: Tuning single section isolator step 3 ..................................................25Figure 25: Tuning single section isolator step 7 ..................................................25Figure 26: Dual section isolator ...........................................................................26Figure 27: Mounting layout for dual section isolator ............................................26Figure 28: Tuning for maximum return loss.........................................................27Figure 29: Tuning for maximum return loss.........................................................27Figure 30: Tuning for passband symmetry ..........................................................28Figure 31: Tuning for reverse isolation ................................................................28Figure 32: Tuning for reverse isolation ................................................................29

Table 1: General specifications 6.625” cavity systems.......................................... 2Table 2: General specifications 8” cavity systems................................................. 3Table 3: General specifications for 10” cavity systems ......................................... 4Table 4: Cavity insertion loss reference loop settings .........................................16

Single section isolator specifications ...................................................................30Dual section isolator specifications......................................................................30Power Ratio and Voltage Ratio to Decibel Conversion Chart .............................31Power In/Out versus Insertion Loss.....................................................................32Power Fwd/Rev versus VSWR............................................................................33

Table of Contents Manual 7-9120-4 11/30/06

GENERAL DESCRIPTIONThe model 73-67-11/18/25-XX-NN Series T-PassTransmit Combiners are designed to connect multi-ple transmitters to a common antenna. They usethree-port bandpass filters (called T-Pass cavities)and dual ferrite isolators to provide low channelinsertion loss, high isolation between transmitters,high antenna-to-transmitter isolation, high inter-modulation suppression, and excellent transmitternoise suppression. T-Pass transmit combiners arebroadband and easily adaptable to the most diffi-cult duplex system design requirements.

The block diagram of a typical transmit combiner isshown in Figure 1. The T-Pass filter passes onenarrow band of frequencies and attenuates all oth-ers with increasing attenuation above and belowthe pass frequency. The T-Pass filter has a “dual-port” output loop plate which allows the filter to beeasily connected to other T-Pass filters. Connec-tions between the filters are made with a “thru-line”cable that behaves like a low loss 50 Ohm trans-mission line. The thru-line cables are individuallyoptimized to their own channel frequency. No com-promises are necessary to accommodate otherchannel frequencies. Each channel can thereforebe anywhere in a very broad frequency range.

An isolator is added at the input to each T-passchannel to increase channel isolation. The ferriteisolators isolate the transmitter from unwanted sig-nals that enter the system via the antenna. Thetransmitter sees an excellent impedance match onits output, because the isolator absorbs reflectedpower that would otherwise enter the transmittersoutput stage. This improves the stability, spectralpurity and long-term reliability of the transmitter.

The model 73-67-11/18/25-XX-NN Series T-Passtransmit combiners are available with either 6.625”,8”, or 10” cavities. TX combiners constructed with6.625” cavities are ideal for operation at channelseparations of 115 KHz or more, with 110 to 150Watt transmitters. These models are suitable for19” Relay rack mounting or TX RX Peg rack mount-ing. TX combiners constructed with high perfor-mance 10” diameter cavities, which have higherselectivity and power handling capabilities, allowoperation at 75 KHz minimum separation with 125to 150 Watt transmitters. In addition, High power10” diameter models are also available which con-tain 250 Watt dual isolators with 100 or 250 Wattloads. Due to their larger physical size 10” diametercavities are mounted in TX RX Peg racks only. TX

combiner models constructed using 8” diametercavities offer a compromise by having good selec-tivity, good power handling, as well as being suit-able for Peg rack or 19” Relay rack mounting.These models will operate at 75 KHz minimum TXchannel spacing’s.

S

TX5

TX4

TX3

TX2

TX1

Transmitter Combiner (T-Pass)

T-PassThru-lineCable

Figure 1: Block diagram of a typical TX T-Pass combiner. 5 channel system shown as example.

TX RX Systems Inc. Manual 7-9120-4 11/30/06 Page 1


Frequency Range 406-512 MHz

Cavity Type and Diameter 3/4 - wave, 6.625” (168mm)

Maximum Isolator Input Power (continuous) 150 W

Isolator Load Power (continuous) * 5W/25W or 5W/100W

Minimum TX - TX Separation @ Cavity Loss 215 KHz @ -1.5 dB; 115 KHz @ -2.5 dB

Typical TX-TX Isolation @ Minimum Separation 80 dB

Typical Antenna - TX Isolation 70 dB

Nominal Input Impedance 50 Ohms

Maximum Input Return Loss (VSWR) 20 dB (1.22:1)

Temperature Range -30° to 60° C

Connectors, Input and Antenna N (F)

Mechanical Mounting Peg Rack ™ or 19” Rack Mount

Mounting Options ** -MC: 19” rack mount adapter plates, 17.5” high

-LR: system supplied without Peg Rack™

Maximum Channels Per Rack 15

Dimensions *** 62.25”H x 24”W x 36”D (1659 x 610 x 914 mm)

Weight, lb/Kg Basic Single Channel System 36/16.3 (25W load) or 37/16.7 (100W load)

Weight, lb/Kg Expansion Channel Assembly 15/6.8 (25W load) or 16/7.2 (100W load)

* Models available with 5W/60W loads. Same specifications as 25W and 100W models, except load power. ** -MC option reduces maximum number of channels to twelve 6.625 inch channels per rack. ** -LR systems are tuned and tested on customer frequencies, then disassembled for shipping. *** Rack depth with cavity tuning rods at maximum frequency. Rod travel is approximately 5.1” (130 mm).

Table 1: General specifications for 6.625” cavity systems.

0

-5

Atte

nuat

ion

(dB

)

-10

-15

-20

-25

-30

-35

-40

-45

-500.01 0.1 1

Offset from Fo (MHz)

10

73-67-11-Series Systems6.625" Diameter 3/4-Wave, Fo = 460 MHz

IL = 1.0 dBIL = 1.5 dBIL = 2.0 dBIL = 2.5 dBIL = 3.0 dB

Figure 2: Typical transmitter noise suppression using 6.625” cavities.



Cavity Type and Diameter 3/4 - wave, 8” (204mm)


Isolator Load Power (continuous) * 5W/100W








Mechanical Mounting 19” Rack Mount

Cavity Length(without tuning rod)

26.8”

Cavity Length(with tuning rod at max/min extension)

34.5”/31”

Weight, lb/Kg Basic Single Channel System 16.6 lbs (including isolator)

Table 2: General specifications for 8” cavity systems.

0

-5

Atte

nuat

ion

(dB

)

-10

-15

-20

-25

-30

-35

-40

-45

-500.01 0.1 1


10

73-67-18-Series Systems8" Diameter 3/4-Wave, Fo = 460 MHz


Figure 3: Typical transmitter noise suppression using 8” cavities.



Cavity Type and Diameter 3/4 - wave, 10” (254mm)


Isolator Load Power (continuous) * 5W/25W or 5W/100W








Mechanical Mounting Peg Rack ™

Mounting Options ** -LR: system supplied without Peg Rack™

Maximum Channels Per Rack 12

Dimensions *** 79.5”H x 24”W x 36”D (2019 x 610 x 914 mm)

Weight, lb/Kg Basic Single Channel System 41/18.6 (25W load) or 42/19.0 (100W load)

Weight, lb/Kg Expansion Channel Assembly 19/8.6 (25W load) or 20/9.1 (100W load)

* Models available with 5W/60W loads. Same specifications as 25W and 100W models, except load power. ** -LR systems are tuned and tested on customer frequencies, then disassembled for shipping. *** Rack depth with cavity tuning rods at maximum frequency. Rod travel is approximately 5.1” (130 mm).

Table 3: General specifications for 10” cavity systems.

0

-5

Atte

nuat

ion

(dB

)

-10

-15

-20

-25

-30

-35

-40

-45

-500.01 0.1 1


10

73-67-25-Series Systems10" Diameter 3/4-Wave, Fo = 460 MHz


Figure 4: Typical transmitter noise suppression using 10” cavities.

The TX combiners can be expanded one channelat a time with factory-tuned, easy-to-install expan-sion channel assemblies. Expansion is usuallyaccomplished without modifications to the existingsystem, and usually amounts to nothing more thanplacing a new channel assembly, or several, on topof the existing system. New channel frequenciescan be above, below, or between existing channelfrequencies.

The number of channels in the combiner is indi-cated by the last two digits of the model number inplace of the NN designation. All of the information

for both installation and expansion is included inthis manual. The combiner is easy to install andhas been factory tuned in most cases so that noadjustments are necessary. The specifications forthe 73-67-11/18/25-XX-NN family of T-Pass com-biners are listed in Tables 1 through 3 for the6.625”, 8”, and 10” cavities respectively. Thecurves in Figures 2 through 4 show the typicaltransmit noise suppression for the 6.625”, 8”, and10” cavity systems respectively. Noise suppressiondepends on the cavity’s loss setting. Figure 5shows a typical Peg rack model and Figure 6shows a typical 19” rack mount model.

Figure 5: Typical Peg-rack model. Figure 6: Typical 19” Relay-rack model.


UNPACKINGIt is important to visually inspect the system com-ponents for any shipping damages as soon as pos-sible after taking delivery. It is the customersresponsibility to file any necessary damage claimswith the carrier.

The transmit combiner is a very rugged device andis well packed for damage-free shipping to anyplace in the world. However, a high impact duringshipping can have a detrimental affect. A damagedshipping container is a sure sign of rough handling.The most easily damaged parts of the combinerare the tuning rods. These rods are marked wherethey exit from the locking nut with a dab of red var-nish or other color/type of paint. If this seal appearsto be broken it may indicate that the system hasbeen detuned in transit.

INSTALLATION OVERVIEWThe combiner should be located in a dry and levelarea, indoors. It is best if all transmitters are asequal in distance as possible from the combiner sothat cable losses are the same for all channels.Figure 7 shows a suggested orientation for theequipment. Two points are important. First, a workarea space should be left as illustrated so that thetuning controls are easy to access. This will facili-ta te tuning when channel f requencies arechanged. Secondly, space is needed when addingexpansion channels. If there is a lack of space toaccess the side of the combiner, then plan to allow

the rack to be moved into the indicated work areato facilitate adding channels. This will require someslack in the cables that connect to the station trans-mitters. Each transmitter connects to its respectivechannel through an ‘N style’ female connector onthe isolator. We recommend using a high qualitydouble shield or semi flexible cable.

This system is designed for use with separatetransmit and receive antennas. For best operation,the transmit and receive antennas should be sepa-rated vertically by 20 feet with little or no horizontaloffset between antennas. Lesser separations canbe used but with an increased risk of harmful inter-ference between radio systems. In most cases, itwill be desirable to mount the receive antennahigher than the transmit antenna to maximize thetalk-back range of low power portable radios.

RF Cables and ConnectorsAll connections to and from the combiner systemshould be made with double-shielded or semi-rigidheliax cable. High quality 'N' connectors that useeither silver or gold plated contacts should beused.

Intermodulation ConsiderationsFollowing the previously mentioned antenna spac-ing recommendations will go a long way towardminimizing or eliminating intermodulation (IM)interference. IM is the result of a frequency mixingprocess that occurs when two or more RF signals

RadioCabinet

RadioCabinet

RadioCabinet

RadioCabinet

WorkArea

T-PassTransmitterCombiner

Figure 7: Typical combiner installation.


are present simultaneously in the same circuitrywhere nonlinearities occur. Product frequenciesgenerated have frequencies that are determined byrelatively simple mathematical relationships suchas F(im) = 2F1-F2 and are normally determined bydoing a computer intermodulation analysis for theantenna site. These products can be generated ina corroded tower joint, metal-roofing, transmitterfinal amplifier or the receiver front-end.

Both cavity filters and ferrite isolators isolate thetransmitters connected to the combiner from one-another thus reducing intermodulation interference.However in all transmitter combiners, intermodula-tion products are reduced in strength but nevercompletely eliminated. They have to be reduced byan amount to meet the federal CommunicationsCommission, 43 + 10 Log(Power Out) rule for spu-rious output reduction. Because of the limitationsimposed by the tension and friction joints in con-nectors, IM products will be down 100 to 120 dBbelow carrier so they are still strong enough tocause problems if they fall on a near-by receiverfrequency. To avoid transmitter generated IM problems, donot put two channels on the same combiner thatyour IM software predicts will cause interference bygenerating either 3rd or 5th order IM products.Having at least two transmitter combiners allowsmaximum flexibility in dealing with transmitter gen-erated IM.

General Installation Procedure1) Install the Peg rack or Relay rack in the radio

equipment room.

2) Connect the transmitters and the transmittingantenna to the appropriate connectors on thecavities.

3) Verify proper operation of each channel bymeasuring the power output for each individualchannel.

TRANSMITTER COMBINER CHECKOUTIt is recommended that the performance of thetransmitter combiner be checked initially and datarecorded for future reference. This is done by mea-suring the input and output power of each channeland recording the data. Figure 8 shows the equip-ment hook up.

Required EquipmentIf a power monitoring system is not installed alongwith the combiner, two Bird Model 43 thruline watt-meters or equivalent can be used. They should beequipped with elements for the frequency band ofinterest and rated for the expected transmitterpower output. The use of two wattmeters elimi-nates errors that can occur from changing cablelengths. The measurements should only be doneone channel at a time because most wattmeterscannot accurately measure the total power of twoor more transmitters simultaneously. A pocket cal-culator with Log functions makes for easy calcula-tion of power loss in dB using this measured data.

PROCEDUREStart with channel 1 and proceed to the next higherchannels. The two wattmeters should be con-nected to the equipment as shown in figure 8. Notethat the use of the elbow and/or male-male con-nectors allows the shortest connections and negli-gible hook up loss. Longer cable lengths will tendto increase measurement error.

It is important that the same wattmeters and watt-meter elements be used in the same positionthroughout the tests. The serial numbers of thewattmeters should be recorded for future refer-ence. Wattmeter elements may not have serialnumbers so they need to be labeled or otherwisekeyed to a specific wattmeter to assure repeatabil-ity of the measurements.

MEASUREMENT ACCURACYThe Bird thruline wattmeter has a measurementaccuracy of +/- 5% of full scale. When using a 100watt element in this meter, the measurement errorcan be as great as + or - 5 watts.

As an example of the actual dB loss readings thatmight be produced using the wattmeter method,consider a T-Pass channel that has a factory mea-sured loss of 3.0 dB. We would expect that a 100watt transmitter would produce 50 watts out of thischannel but the actual wattmeter reading for theinput power could measure as low as 95 watts toas high as 105 watts. The measured output powercould run from 45 to 55 watts. It is possible that theoutput reading may be 5 watts low while the inputreading is 5 watts high or just the opposite. Thesetwo extremes would yield the following dB loss val-ues:


For a Power Out (PO) of 45 watts and a PowerInput (PI) of 105 watts:Loss (dB) = 10 Log10 (45/105)Loss (dB) = -3.7

For a PO of 55 watts and PI of 95 watts:Loss (dB) = 10 Log10 (55/95)Loss (dB) = -2.4

So the calculated loss for this channel can run from-2.4 to -3.7dB and be acceptable considering themeasurement error factor. The actual error couldbe much greater i f a 250 watt element wasused; the measured values could vary by as muchas +/- 12.5 watts so using a wattmeter element withthe smallest possible rating is important for accu-racy. Use of between series adapters or UHF type

connectors for making connections to the wattme-ters, device under test or loads could make thiserror even worse due to the additional impedancemismatch that these connectors can cause.

GENERAL TUNING INFORMATIONT-Pass transmitter combiners are pre-tuned at thefactory and usually require no adjustment. T-Passexpansion channels are also pretuned but mayrequire fine tuning after being installed in an exist-ing system. Channels that are close in frequency(adjacent channels in the multicoupler) to theexpansion channel may also benefit from fine tun-ing due to the slight interaction that occurs with thenew channel. The procedures that follow may beused at any time to verify that any or all channelsare properly tuned or to correct any misalignments.

CALIBRATIONINDEX0 510

1520

CALIBRATION

INDEX

0

510 15 20


1520

CALIBRATION

INDEX

0

510 15 20


1520

CALIBRATION

INDEX

0

510 15 20

0

1020

2040

3060

4080 50100

510 15

20

WATTSTHRULINE

BIRD ELECTRONIC CORP.

0

1020

2040

3060

4080 50100

510 15

20

WATTSTHRULINE

BIRD ELECTRONIC CORP.

UG27 Elbow Connector& UG57 Male-Male

Adaptor

UG57Male-Male

Transmitter

Transmitter

Single or DualSection Isolators


Transmitter


T-PassCavity Filter

Channel 3

Channel 2

Channel 1

Wattmeter 2

50 OhmLoad

Wattmeter 1

This T-Pass Looprequires a 3-1268

short circuitconnector

Figure 8: Equipment hookup for measuring T-Pass channel performance.


It is interesting to note that T-Pass filters, bandpassfilters and cavity filters in general can act as imped-ance transformers as well as filters. It is for thisreason that many field service personnel claim thatthey can always tune a filter or duplexer better thanthe factory. What isn't generally realized is thattheir tuning efforts are usually producing betterimpedance matching between transmitter andantenna which can be improved by the transform-ing action of filters. Since the filters are usuallytuned using laboratory grade 50 ohm loads, thetuning adjustment that produces this improvedmatch will be slightly different than the factoryadjustment. While this tuning may produce slightlygreater power output readings, it will rarely pro-duce any discernible change in system perfor-mance and may detune any notching circuitrycontained in the cavities.

It is our recommendation that channel tuning onlybe attempted under the previously mentioned con-ditions or when it is suspected that the combinerhas been tampered with or subjected to extremeshock in shipping or installation. This condition is

indicated when the channel loss is in excess of thatexpected from actual measurement of power inputand output.

Tuning Specifics Tuning of the combiner consists of tuning the indi-vidual T-Pass channels. T-Pass channel tuninginvolves both isolator and cavity filter tuning. Theprocedures for tuning cavities follows.

FINE CAVITY TUNINGFigure 9 shows hookups which are suitable for finetuning any channel under power while installed inthe combiner. The term fine tuning here refers tocavities that have already been tuned to frequencyand may only require adjustment of the fine tuningcontrol (+/- 50 KHz). The transmitter is used as asignal source and the cavity is adjusted for mini-mum reflected power.

ProcedureWith the transmitter keyed, the cavity fine tuningcontrol is adjusted (pushed in or out) to obtain aminimum meter reading. See Figure 10 for a detail


1520

CALIBRATION

INDEX

0

510 15 20

0

1020

2040

3060

4080

50100

510

1520

WATTS

TH

RU

LINE

BIR

D E

LEC

TR

ON

IC C

OR

P.

Transmitter

Two Single SectionIsolators or Dual Isolator

Input

T-PassCavity Filter

Wattmeter

OutputSectionTermination

Output

50 OhmTermination

FineTuning

CoarseTuning

To Other Channels

To Other Channels

Figure 9: Using a wattmeter for T-Pass cavity fine tuning.


of the cavity tuning controls. If a minimum meterreading is obtained with the fine tuning rod fully inor completely out, do the following:

1) Set the fine tuning rod so that about 1/2 itslength is inserted into the cavity.

2) Loosen the coarse tuning rod locking screw (5/32”/4mm Allen/Hex-key wrench required) andmove the rod in or out slightly to obtain mini-mum meter reading. Small movements of thecoarse tuning rod are facilitated by tapping therod with the handle end of a screw driver whilegently pushing or pulling the main tuning rod.Tighten the coarse tuning locking screw.

3) Adjust the fine tuning control for a minimummeter reading.

4) Tighten the fine tuning locking mechanism.

CAVITY TUNING TIPWhen tuning a cavity that has been in service forsome time it is not unusual to find the main tuningrod hard to move in or out. This occurs because TXRX uses techniques borrowed from microwave

technology to provide large area contact surfaceson our tuning plungers. These silver plated sur-faces actually form a pressure weld that maintainsexcellent conductivity. This pressure weld devel-ops over time and must be broken to move themain tuning rod. This is easily accomplished bygently tapping the tuning rod with a plastic screw-driver handle or small hammer so that it moves intothe cavity. The weld will be broken with no damageto the cavity.

When adjusting the coarse tuning rod, it is easy toput the cavity far off resonance and cause most ofthe transmitter power to be reflected back into theisolator output section load. This load should becapable of dissipating this power or damage couldresult. If in doubt about the loads capability, followthe coarse tuning procedure outlined below. It isbased on the use of a tracking generator whichavoids the need to consider power levels.

COARSE CAVITY TUNINGWhen a T-Pass cavi ty frequency has to bechanged by over 100 KHz, adjustment of the maintuning rod is required. Large frequency changesare more easily observed when using a tracking

Raises Freq.

Lowers Freq.

FineTuningRod

MainTuningRod

5/32" Allen HeadLocking Screw,

Main Tuning

LockingThumb Nut,Fine Tuning

Raises Freq.

Lowers Freq.

Figure 10: T-Pass cavity tuning control details.


generator and a return loss bridge to give a sweptdisplay of the return loss curve. The return losscurve is a very precise indicator of T-Pass cavitytuning. The test equipment hookup for doing this isillustrated in Figure 11 and uses the followingequipment or its equivalent;

1) IFR A-7550 Spectrum Analyzer / Tracking gen-erator combination.

2) Eagle Return Loss Bridge (35 dB directivity).Model RLB150N3A.

3) Double shielded coaxial cable test leads(RG142 B\U or RG223/U).

4) 50 Ohm load with at least -35 dB return loss(1.10:1 VSWR).

5) 3-1268 short circuit connector.

PROCEDURE1) Set the tracking generator for the desired chan-

nel frequency (display center) and vertical scaleof 10 dB/div.

2) Connect the return loss bridge to the trackinggenerator as shown in figure 11 but do not con-nect it to the cavity. Leave the test port (calledthe load port) on the bridge open.

3) Set up the 0 dB return loss reference.

Note: for the IFR 7550 do the following procedure:

a) Make sure that the unit is in "LIVE" mode.

b) From the Mode Menu, "STORE" the abovetrace.

c) Switch to the Display Menu and select"REF". The trace should appear at the 0 dBlevel.

4) Loosen the fine tuning rod locking nut and setthe fine tuning rod so that 1/2 its length isinserted into the cavity.

5) Loosen the main tuning rod locking screw andmove the main tuning rod in or out to obtainmaximum return loss at the desired frequency.Small movements of the main tuning rod arefacilitated by tapping the rod with the handleend of a screw driver while gently pushing orpulling the main tuning rod.

6) Lock the Main and Fine tuning rods and recon-nect the cavity into the multicoupler system.Use the previously outlined fine tuning proce-dure to verify proper tuning under power.


1520

CALIBRATION

INDEX

0

510 15 20

SC

LOADRE

FLE

CT

ED

SO

UR

CE

AnalyzerInput

GenerateOutput

+30

+40

+20

+10

0

-10

-20

-30

-40

RLB - 150 Bridge

50 Ohm Load

T-PassCavity Filter

3-1268Short Circuit

Connector

Tracking Generator

Figure 11: Coarse tuning a T-Pass cavity.


Retuning System To All New FrequenciesWhen retuning the combiner to all new frequenciesperform the following procedure in a step-by-stepfashion;

1) Determine new thruline cable lengths for thenew channels and the specific stacking order inthe rack. TX RX Systems Sales engineers willassist by making the calculations using theirdesign software. Due to variations in coaxialcable characteristics and assembly techniques,factory supplied cables are recommended.

2) Use the Coarse Tuning procedure to tune eachcavity channel to the new transmitter frequen-cies.

3) Connect the channels according to the newthru-line cable chart.

4) Fine tune each channel using the fine tuningprocedure starting with channel 1 and proceed-ing to the next higher channel. After tuning allchannels, repeat this step a second time to ver-ify that their is no more channel interaction.

5) Verify channel losses if desired using thecheckout procedure outlined previously.

Combiner ExpansionExpansion channels for your combiner may beordered directly from TX RX Systems or its autho-rized representative. If you wish, a TX RX systemsengineer will help you select the right model andany required options.

The expansion channel and options are shippedwith mounting instructions and a new T-PassThruline cable sheet which shows the exact mount-ing location of the new channel in the existing mul-ticoupler. In most cases, this channel will beadded directly to the next topmost position in therack and the antenna connection will then move tothis cavity. A new thruline cable will connect thischannel to the existing cavities.

The system engineer may also advise that the cav-ity insertion loss on some of the existing channelsneeds to be changed in order to accommodate anew channel. This can be necessary when the newchannel is much closer in frequency separation toexisting channels than that previously encoun-tered. This usually means increasing the cavityloss for all close spaced channels which provides

the increased selectivity required. Cavity insertionloss values are shown on the T-Pass Thrulinecable sheet.

Typical Expansion Channel installation The following text is a procedure for adding expan-sion channel components to a typical T-PassTransmit Combiner system. Please keep in mindthat instructions shipped with the expansion com-ponents supersede these procedures.

Typical Parts Included: (Quantity and Description)

(1) T-Pass Cavity Assembly.

(1) Dual or single isolator with load(s).

(1) Isolator to cavity interconnect cable.

(1) Cavity and isolator mounting hardware.

(1) T-Pass thru-line cable.

(1) T-Pass thruline chart.

PEG RACK PROCEDURE1) Determine the location of the Expansion Chan-

nel in the rack by consulting the newTHRULINE cable chart.

2) Mount the cavity in the peg rack using two (2)

stainless band clamps, refer to Figure 12.

3) Rotate the cavity body so that the connectorsare oriented the same as those on the othercavities and that no cavity-end cap screws arepreventing a flush fit with a mounting peg.

4) Tighten the cavity mounting clamps.

5) Attach the isolator mounting plate to the cavityusing two (2) band clamps. Clamp screwsshould be positioned as shown in figure 12. Donot tighten the clamps.

6) Rotate the isolator mounting bracket so that theisolator is in the vertical plane as illustrated,forming a smooth line in relation to the otherchannels in the rack.

7) Due to the limited space, tightening may requirethe use of a 5/16" open end wrench. Tightenboth clamps securely.


8) Connect the black isolator-to-cavity cable usinga pair of cable pliers to tighten-up the connec-tors.

9) Connect the new channel to the combiner usingthe proper length T-Pass Thruline cable. Use apair of cable pliers to tighten these connections.

The required length thruline cable andnew cabling chart has either been fac-tory supplied or is to be determinedand fabricated by the customer asdetermined at the time of order. UseT-Pass thruline design sheets sup-plied by the factory.

10) If necessary, reset the cavity insertion loss ofadjacent channels as noted on the Thru-linecable sheet. Follow the procedure outlinedbelow under Setting Cavity Insertion Loss.

11) Fine tune the T-Pass cavity of the expansionchannel according to the fine tuning procedureoutlined earlier.

RELAY RACK PROCEDURE1) Determine the location of the Expansion Chan-

nel in the rack by consulting the newTHRULINE cable chart.

2) If necessary install an empty cavity deck in therack using 4 Phillips screws. If there is room onan already existing cavity deck then skip thisstep of the procedure.

3) Mount the cavity on the deck by laying the cav-

ity onto the two ‘V shaped’ cavity brackets.

4) Rotate the cavity body so that the connectorsare oriented the same as those on the othercavities in the system. Secure the new cavity to

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Cavity mountingclamp goesaroundtwo pegs

Cavity and isolatorclamp screws in thisapproximateposition

Cavity bodyrests againsttwo pegs

Figure 12: Peg rack mounting details.


the brackets using the two (2) stainless bandclamps, refer to Figure 13.

5) Tighten the cavity mounting band clamps.

6) If necessary install an empty isolator deck in therack using 4 Phillips screws. If there is room onan already existing isolator deck then skip thisstep of the procedure.

7) Attach the Isolator mounting plate to the anglebracket using three (3) screws.

8) Install the mount plate / angle bracket to the iso-lator deck in the next open position and securein place with two (2) screws.

9) Install the isolator to the mounting plate with 4screws. Make sure the isolator is oriented thesame as the other isolators in the system.

10) Install one end of an extension cable (3-13533)to the sampler port on the output load of theisolator. Attach the other end of the extensioncable to a mounting bracket and attach the

CALIBRATION

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ate R

otate

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ate R

otate

Rot

ate R

otate

Figure 13: Relay rack mounting details.

Isolator deck attaches to rack with four (4)

screws.

Cavity deck attaches to rack with four (4)

screws.

Cavity rests on a pair of V-shaped clamps.

Cavities mount to top and bottom of deck


bracket to the front of the deck near the isola-tor. This extension cable will allow easy accessto the sampler port for future testing.

11) Connect the black isolator-to-cavity cable usinga pair of cable pliers to tighten-up the connec-tors.

12) Connect the new channel to the combinerusing the proper length T-Pass Thruline cable.Use a pair of cable pliers to tighten these con-nections.

The required length thruline cable andnew cabling chart has either been fac-tory supplied or is to be determinedand fabricated by the customer asdetermined at the time of order. UseT-Pass thruline design sheets sup-plied by the factory.

13) If necessary, reset the cavity insertion loss ofadjacent channels as noted on the Thru-linecable sheet. Follow the procedure outlinedbelow under Setting Cavity Insertion Loss.

14) Fine tune the T-Pass cavity of the expansionchannel according to the fine tuning procedureoutlined earlier.

Setting Cavity Insertion LossIt is sometimes necessary to reset the insertionloss of a T-Pass cavity filter in order to change itsselectivity. Increasing the loss will increase thecavity selectivity which may be necessary toaccommodate more closely spaced channels.

Changing the loss is accomplished by rotating thecoupling loops to change the coefficient of cou-pling. Both loops are normally adjusted for a giveninsertion loss setting. Most T-Pass cavities have aCalibration Index label beside both loops that givesa relative indication of their settings, see Figure14. In actual practice, these marks are not accurateenough for setting different loss values consis-tently.

Two procedures are offered for setting the cavityloss. Both procedures take advantage of the factthat when a tee connector is placed on a singlebandpass or T-Pass loop, a rejection notch can beobserved across the tee. The depth of the rejectionnotch is directly related to the loop's coefficient ofcoupling.

The first procedure uses precision rotary attenua-tors, a signal generator and a RF millivolt meter toprovide very accurate results. The actual loss set-ting obtained when this procedure is carefully fol-lowed will be within one tenth of a dB of the desiredvalue and the return loss will be 20 dB (1.25:1) orbetter.

The second procedure uses an IFR A-7550 Spec-trum Analyzer with a built-in tracking generator andproduces slightly less accurate results. When thisprocedure is carefully followed, the loss settingswill be within two tenths of a dB of the desiredvalue and the return loss will usually be -15 dB(1.5:1 VSWR) or better. The advantage of this pro-cedure is that it is much faster to do, does notrequire precision attenuators and will yield accept-able results in most cases.

Table 4 is a reference chart for setting T-Pass cav-ity loss with either procedure. The chart shows thedesired cavity loss settings and the reference set-ting for both the T-Pass and bandpass loop assem-bly. The reference notch depth for a given loss isthat which can be observed across a tee connectorconnected to either loop assembly.

Cavity Loss Setting Procedure 1This procedure uses precision rotary attenuators, asignal generator and an RF millivolt meter.

REQUIRED TEST EQUIPMENT1) Signal generator capable of producing a CW

signal level of at least -10 dBm with variable

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Mark

BandpassLoop

T-PassLoop

Loop LockingScrews (6 places)

Rotate

Rotate

Figure 14: Top view of T-Pass cavity.


output level capability at the frequency of inter-est.

2) An RF voltmeter with a 0.001 V (-50 dBm)scale and a 50 ohm input adapter. HelperInstruments RF millivolter used for this exam-ple.

3) Rotary Attenuators, 1@ 0-1 dB in 0.1 dB incre-ments. 1@ 0-10 dB in 1.0 dB increments. 1@0-70 dB in 10 dB increments. JFW Industriesmodel 50BR-017.

4) Two 10 dB fixed attenuator pads with BNCconnectors. JFW Industries model 50F-010.

5) UG-914/U, BNC(F) to BNC(F) union.TX RX Systems' part # 8-5805.

6) UG-28A/U, N(F), N(F), N(F) tee.

7) UG-57B/U, N(M)-N(M) coupling.

8) Two, UG-201A/U BNC(F)-N(M) adapter.TX RX Systems' part # 8-5814.

9) 50 ohm coaxial cable test leads with BNC maleconnectors (high quality cable).

A spectrum analyzer may be used in place of theRF voltmeter. However, the personnel doing thework should fully understand the procedure andunderstand the use of the analyzer for this applica-tion.

We have found it convenient to use test cables withBNC connectors. They allow for more convenientconnection to test equipment and to small attenua-tor pads. UG-201 BNC to N adapters are usedwhen connections to N connectors are needed.

PROCEDURE FOR T-PASS LOOP1) Set the signal generator at the desired fre-

quency (within 1 MHz of operating frequency)and an output level of approximately -10 dBm.Set the rotary attenuators for the ReferenceNotch Depth Value shown in table 4 for thedesired insertion loss.

2) Connect the test leads together through thefemale union, as shown in Figure 15, andadjust the range switch and the zero set on thevoltmeter for a convenient reference level (A

Cavity Loss (dB) Coupling Loop Type TXRX Part # Reference Notch Depth

1.0 T-Pass 3-3724 -9.2Bandpass 2-0675 -12

1.5 T-Pass 3-3724 -7.4Bandpass 2-0675 -10.2

2.0 T-Pass 3-3724 -5.6Bandpass 2-0675 -8.8

2.5 T-Pass 3-3724 -4.4Bandpass 2-0675 -8.0

3.0 T-Pass 3-3724 -3.6Bandpass 2-0675 -7.2

Table 4: Cavity insertion loss reference loop settings.


level of 2 on the 0 to 3 scale for example) on themeter. The generator output level may also beadjusted slightly if necessary.

3) Remove the bandpass loop from the cavity andreinsert it, connector end first, back into the cav-ity and tighten all 3 screws securely. See Fig-ure 16.

4) Set all three attenuators for 0 dB but leave themin the circuit.

5) Connect a UG-28A/U Tee connector and UG-57B/U coupling to the T-Pass loop as shown infigure 16. Then connect the test leads asshown. Make sure to install the 3-1268 short cir-cuit connector from the top of the T-Pass rack.

6) Loosen the main tuning rod locking screw andslowly slide the tuning rod in or out to obtain adip (minimum voltage) in the meter readingwhich indicates cavity resonance. Use the finetuning control to maximize the dip (the fine tun-ing rod should not be full in or out which wouldindicate that slight adjustment of the main tun-ing rod is necessary). Note the meter reading.

7) If the meter reading is greater or less than thereference level from step 2, the T-Pass looprotation will have to be adjusted. If the meterreading is greater than the reference level, theloop will have to be rotated so that the calibra-tion mark on the loop points to a slightly highernumber on the calibration index label. Con-versely, if the meter reading is less than the ref-erence, the loop will have to be rotated so thatthe index mark points to a slightly lower numberon the calibration index. Loosen the three looplocking screws and rotate the loop so that theindex mark is moved to the next higher or lowercalibration tag number as needed and tightenthe 3 locking screws. Note that tight screws arenecessary for accuracy.

8) Repeat steps 6 and 7 until the minimum meterreading is equal to the reference level from step2. Rotation of loops will change the cavity fre-quency slightly.

9) The Bandpass loop should be reinstalled withthe connector facing upward and the groundpoint circle oriented toward the center of thecavity as shown in Figure 17.

DIRECT 50 dB PAD

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.0dBm

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UG914/UFemale-FemaleConnector

10 dB Attenuator Pads

Rotary AttenuatorsSet to Loop Reference Settings

0.1 dB/Div. 1.0 dB/Div. 10 dB/Div.

50 Ohm Adaptor

All cables are 50 Ohm

coaxial. Double shielded

cables preferred.

Figure 15: Setting loop adjustment reference level.


10) Remove the short circuit connector from the T-Pass loop

PROCEDURE FOR BANDPASS LOOP1) Maintain the previous signal generator settings

and set the rotary attenuators for the proper set-ting as shown in table 4 for the Bandpass Loop.

2) Connect the test leads together through thefemale union and adjust the range switch andthe zero set on the voltmeter for a referencelevel (A level of 2 on the 0 to 3 scale is conve-nient) on the meter. See figure 15. The genera-tor output level may also be adjusted slightly ifconvenient.

3) Set all three attenuators for 0 dB but leave themin the circuit.

4) Connect a UG-107 Tee and the UG-57B/U tothe Bandpass loop as shown on figure 17. Then

connect the test leads as shown. Make sure theshort circuit connector has been removed fromthe T-Pass loop.

5) Loosen the main tuning rod locking screw andslowly slide tuning rod in or out to obtain a dip(minimum voltage) in the meter reading whichindicates cavity resonance. Use the fine tuningcontrol to maximize the dip (the fine tuning rodshould not be full in or out which would indicatethat slight adjustment of the main tuning is nec-essary). Note the meter reading.

6) If the meter reading is greater or less than thereference level from step 2, the bandpass looprotation will have to be adjusted. If the meterreading is greater than the reference level, theloop will have to be rotated so that the calibra-tion mark on the loop, points to a slightly highernumber on the calibration index label. Con-versely, if the meter reading is less than the ref-

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Short Circuit Connector 3-1268from top of rack


50 Ohm Adaptor

UG-28A/U

UG-57B/U

T-Pass Loop

Bandpass Loop turned upside downwith connector inserted into cavity.Loop visible and screws tight.

10 dB Pad 10 dB Pad

Figure 16: Setting the T-Pass loop using step attenuators.


erence, the loop will have to be rotated so thatthe index mark points to a slightly lower numberon the calibration index. Loosen the three looplocking screws and rotate the loop so that theindex mark is moved to the next higher or lowercalibration tag number as needed and tightenthe 3 locking screws. Note that tight screws arenecessary for accuracy.

7) Repeat steps 5 and 6 until the minimum meterreading is equal to the reference level from step2. Rotation of loops will change the cavity fre-quency slightly.

8) Make sure that all the loop locking screws aretight. The cavity loops are now set and the cav-ity should now be tuned to the desired fre-quency.

Cavity Loss Setting Procedure 2This procedure uses a spectrum analyzer andtracking generator.

REQUIRED TEST EQUIPMENT1) IFR A-7550 Spectrum Analyzer / Tracking gen-

erator combination.

2) Two 10 dB fixed attenuator pads with BNCconnectors. JFW Industries model 50F-010.

3) UG-914/U, BNC(F) to BNC(F) union.TX RX Systems' part # 8-5805.

4) UG-28A/U, N(F), N(F), N(F) tee.

5) UG-57B/U, N(M)-N(M) coupling.

6) Two, UG-201A/U BNC(F)-N(M) adapter.TX RX Systems' part # 8-5814.

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50 Ohm Adaptor

UG-28A/U

UG-57B/U

T-Pass Loop

Previously calibrated T-Pass Loop 3-1268short circuit removed.

10 dB Pad 10 dB PadRotate

Small circle on bandpass loop indicatesground end of loop and should beoriented as shown.

Figure 17: Setting the bandpass loop using step attenuators.


7) 50 ohm coaxial cable test leads with BNC maleconnectors (high quality cable).

Other spectrum analyzer and tracking generatorcombinations are acceptable if they provide theequivalent range and resolution of the A-7550. Wehave found it convenient to use test cables withBNC connectors. They allow for a more convenientconnection to test equipment and small attenuatorpads. UG-201 BNC to N adapters are used whenconnections to N connectors are needed.

PROCEDURE FOR T-PASS LOOP1) Remove the screws that hold in the bandpass

loop assembly; remove the assembly; invert itand place it back into the cavity (see Figure

18). The coupling loop will be visible. Install andtighten the three locking screws.

2) Connect the test leads to the A-7550; turn it onand let it warm up for at least 30 minutes.

3) Connect the 10 dB attenuator pads to the testleads. They will remain connected for all subse-quent measurements.

4) Note the Reference Notch Depth value for theT-Pass loop assembly to be adjusted from table4.

5) Set the A-7550 for the frequency of the channelof interest (within 1 MHz of actual operating fre-quency).

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UG-28A/U

UG-57B/U

T-Pass Loop

Bandpass Loop turned upside downwith connector inserted into cavity.Loop visible and screws tight.

10 dB Pad 10 dB Pad

AnalyzerInput

GenerateOutput

+30

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+20

+10

0

-10

-20

-30

-40

Spectrum Analyzer/Tracking Generator

Figure 18: Setting a T-Pass loop for specific cavity insertion loss.


Mode = LiveScan Width = 100 KHz/div.Resolution BW = 30 KHzGenerator Output = 0 dBmAttenuator = -30 dBIF Gain set for 0 dBm at top of display grati-cule.

6) If the Reference Notch Depth is 8 dB or lessthen set the display for a vertical range of 2dB/div otherwise set it for 10dB/div.

7) Temporarily connect the test leads from the A-7550 together through a UG-914 BNC union toset the zero reference.

Note:On the IFR A-7550 proceed as follows:

a) Activate the Mode Menu and make sure thatthe unit is in "LIVE" mode.


c) Switch to the Display Menu and select "REF".A 0 dB reference trace will appear on the dis-play.

d) Exit the menu.

8) Connect a UG-28 tee and a UG-57 coupling tothe T-Pass loop as shown in figure 18.

9) Connect the test leads from the A-7550 to thetee connector as shown in figure 18.

10) Adjust the cavities main tuning rod so that arejection notch appears in the center of the dis-play.

11) Loosen the three loop locking screws androtate the loop to obtain the reference notchdepth from step 4. Tighten the T-Pass looplocking screws only. Note that the tightness ofthe locking screws affects the depth of therejection notch slightly. It is usually necessaryto rotate the loop for a notch depth that isslightly less than the reference. The Notchdepth will tend to increase slightly as all threelocking screws are tightened.

12) Remove the bandpass loop and place it backinto the cavity with the connector-end up.

PROCEDURE FOR BANDPASS LOOP1) The Bandpass loop should be installed with the

connector up and the ground point circle ori-ented toward the center of the cavity as shownin Figure 19.

2) Connect the test leads, with 10 dB padsattached, to the A-7550; turn it on and let itwarm up for at least 30 minutes if this has notbeen done.

3) Note the Reference Notch Depth value for theBandpass loop assembly to be adjusted fromtable 4.

4) Set The A-7550 for the frequency of the chan-nel of interest (within 5 MHz of actual operatingfrequency).

Mode = LiveScan Width = 100 KHz/div.Resolution BW = 30 KHzGen Output = 0 dBmAttenuator = -30 dBIF Gain set for 0 dBm at top of display graticule.

5) If the Reference Notch Depth is 8 dB or lessthen set the display for a vertical range of 2dB/div otherwise set it for 10dB/div.

6) Temporarily connect the test leads from the A-7550 together through a UG-914 BNC union toset the zero reference. Make sure to use the 10dB pads which should remain on the test cablesfor all measurements.

Note:On the IFR A-7550 proceed as follows:

a) Activate the Mode Menu and make sure thatthe unit is in "LIVE" mode.


c) Switch to the Display Menu and select "REF".A 0 dB reference trace will appear on the dis-play.

d) Exit the menu.

7) Connect a UG-28 tee and a UG-57 coupling tothe bandpass loop as shown in figure 19.


8) Connect the test leads from the A-7550 to thetee connector as shown in figure 19.

9) Adjust the cavities main tuning rod so that arejection notch appears in the center of the dis-play.

10) Loosen the three loop locking screws androtate the loop assembly to obtain the refer-ence notch depth from step 3. Note that thetightness of the locking screws affects thedepth of the rejection notch slightly, it is usuallynecessary to rotate the loop for a notch depththat is slightly less than the reference. TheNotch depth will tend to increase slightly as allthree locking screws are tightened.

11) Tighten all loop locking screws. The cavity lossis now set. The cavity will have to be tuned toits operating frequency following the proce-dures outlined earlier in this manual.

ISOLATORSIsolators perform two important functions. Their pri-mary function is to keep other RF frequencies outof the transmitter so that intermodulation productscannot be generated. Isolators have a substantialamount of reverse isolation. They also ensure thatthe transmitter never sees any significant reflectedpower so it will always operate with maximum sta-bility at full-power output. Isolators prevent energyfrom getting into the transmitters output by dump-ing any RF energy entering the output of the isola-tor into a dummy load. For a more detai leddiscussion of the construction and theories of oper-ation of ferrite isolators refer to the TX RX SystemsInc. publication “SEMINAR SUBJECTS” titled “AnElementary Introduction to Ferrite Isolators, Circu-la to rs and RF Loads ” ( l i te ra ture numberC2003H92). Contact your TX RX sales representa-tive if you wish to order a copy.

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T-Pass Loop

10 dB Pad 10 dB Pad

AnalyzerInput

GenerateOutput

+30

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-10

-20

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Spectrum Analyzer/Tracking Generator

Previously calibrated T-Pass Loop 3-1268short circuit removed.

Small circle on bandpass loop indicatesground end of loop and should beoriented as shown.

Rotate

Figure 19: Setting a bandpass loop for specific cavity insertion loss.


The model 73-67-11/18/25-XX-NN series of T-passtransmit combiners will use either single section ordual section isolators at the input to each T-passchannel. At UHF frequencies the rated specifica-tions of the isolators are maintained over a 1%range which equals a bandwidth of about 4.59 MHz(at a center frequency of 459 MHz). When the iso-lators frequency of operation is being changed bygreater than 0.4% (about 2.0 MHz) then tuning ofthe isolator will ensure optimum performance. Thissection of the manual deals primarily with the pro-cedures necessary for field tuning the ferrite isola-tors to new frequencies.

SINGLE-SECTION ISOLATORSSingle-section isolators have one load port. A prop-erly sized load capable of dissipating the maximumexpected reflected power that might be encoun-tered should be used.

The isolator loads can get quitehot during operation. This canoccur when an antenna systemcomponent fails causing highreflected power which is then dis-sipated by the isolator load. Theseloads can get hot enough to burnskin so use caution when servic-ing these devices.

TuningIt is assumed that the tuning procedures in thismanual will be carried out by a skilled electronicstechnician who is familiar with the communicationssystem. Refer to Figures 20 and 21 during the tun-ing procedure. The tuning procedure should be fol-lowed in a step-by-step fashion.

REQUIRED EQUIPMENTThe following equipment or its equivalent is recom-mended:

1) IFR Model A-7550 Spectrum Analyzer/Track-ing generator combination or equivalent.

2) Eagle RLB-150 Return Loss Bridge (35 dBdirectivity).

3) Double shielded coaxial cable test leads(RG142 B/U or RG223/U).

0.250"(6 mm)

3.000" (76 mm)

0.375" (10 mm)

1.12

5"(2

9 m

m)

1.50

0"(3

8 m

m)

.21" (6 mm) dia 4 places

Figure 21: Mounting layout of the single section UHF isolator.Figure 20: Single section UHF isolator.


4) 50 Ohm load with at least -35 dB return loss(1.10 : 1 VSWR).

5) Metal blade tuning tool for adjusting ceramicand/or piston variable capacitors (TX RX Part#95-00-01).

TUNING PROCEDUREIt is necessary to be able to set zero references forboth insertion loss and return loss measurementsin order to determine if specifications are beingmet. This procedure is not outlined in the A-7550manual but consists of using the “STORE” tracefunction to save the reference trace level and thenputting the A-7550 into the reference mode whichmakes this stored trace the zero reference. Theprocedure for doing so is outlined below.

SETTING 0 DB INSERTION LOSS REFERENCESet the A-7550 for the desired frequency andbandwidth. Connect the output and input leadstogether through a female barrel connector (UG 29-N or UG 914 -BNC) and proceed as follows:

1) Make sure that the unit is in “LIVE” mode.

2) From the Mode Menu, “STORE” the trace.

3) Switch to the Display Menu and select “REF”.The trace should appear at the 0 dB level.

SETTING 0 DB RETURN LOSS REFERENCESet the A-7550 for the desired frequency andbandwidth. Connect the Return Loss Bridge to theA-7550 but leave the LOAD port open. Repeatsteps 1, 2, and 3 above. (see Figure 22).

1) Set the 0 dB return loss reference.

2) Connect the bridge to the isolator as shown inFigure 23 and adjust capacitor 1 for maximumreturn loss at the center frequency.

3) Reverse the bridge and load connections asshown in Figure 24 and adjust capacitor 3 formaximum return loss at the center frequency.

Bridge

AnalyzerInput

GenerateOutput

+30

+20

+10

0

-10

-20

-30

TUNE1

2

3

Good Quality50 Ohm Load

Single StageUHF IsolatorLoad that will

be used duringactual operation.

Figure 23: Tuning the single section isola-tor step 2.

RLB - 150 Bridge

AnalyzerInput

GenerateOutput

+30

+20

+10

0

-10

-20

-30

Re

flect

ed

So

urc

e

Load

To device to be tested.This connector left open

for setting 0 dB reference.

Figure 22: Proper connection of an Eagle RLB-150 Return Loss Bridge.


4) Disconnect the bridge from the isolator and thetest leads from the bridge.

5) Set the 0 dB insertion loss reference.

6) Connect the leads to the isolator as shown inFigure 25.

7) Adjust capacitor 2 for minimum signal at thecenter frequency. This adjustment minimizesreverse isolation.

8) Repeat steps 1 through 7.

The single section isolator is now tuned and maybe placed back into service.

DUAL-SECTION ISOLATORSDual section isolators have two load ports, one foreach section. Although loads of equal power ratingmay be used for both ports, it is customary to use

an output load capable of dissipating the maximumexpected reflected power that might be encoun-tered. A small load (5 watts) is usually installed onthe first section of the isolator where high reflectedpower is not a factor.

The isolator loads can get quite hotduring operation. This can occurwhen an antenna system compo-nent fails causing high reflectedpower which is then dissipated bythe isolator load. These loads canget hot enough to burn skin so usecaution when servicing thesedevices.

TuningIt is assumed that the tuning procedures in thismanual will be carried out by a skilled electronicstechnician who is familiar with the communicationssystem. Refer to Figures 26 and 27 during the tun-ing procedure. The tuning procedure should be fol-lowed in a step-by-step fashion.


AnalyzerInput

GenerateOutput

+30

+20

+10

0

-10

-20

-30

TUNE1

2

3

RF


Bridge

AnalyzerInput

GenerateOutput

+30

+20

+10

0

-10

-20

-30

TUNE 3

2

1

50 OhmLoad


REQUIRED EQUIPMENTThe following equipment or its equivalent is recom-mended:

1) IFR Model A-7550 Spectrum Analyzer/Track-ing generator combination or equivalent.

2) Eagle RLB-150 Return Loss Bridge (35 dBdirectivity).

3) Double shielded coaxial cable test leads(RG142 B/U or RG223/U).

4) 50 Ohm load with at least -35 dB return loss(1.10 : 1 VSWR).

5) Metal blade tuning tool for adjusting ceramicand/or piston variable capacitors (TX RX Model# 95-00-01).

Figure 26: A typical dual-section isolator.

InputConnector

OutputConnector

Remove screws toaccess tuning

capacitors

Input SectionLoad

Output SectionLoad

Remove caps toaccess tuning

capacitors

Remove caps toaccess tuning

capacitors

1.438"37 mm

3.250"83 mm

4.688"120 mm

0.313"8 mm

5.500"140 mm5.813"

148 mm

0.188"5 mm

3.125"79 mm

3.313"84 mm

0.219" (6 mm) DiaMounting Holes4 places

Figure 27: Mounting hole layout of the dual isolator.


TUNING PROCEDUREIt is necessary to be able to set zero references forboth insertion loss and return loss measurementsin order to determine if specifications are beingmet. This procedure is not outlined in the A-7550manual but consists of using the “STORE” tracefunction to save the reference trace level and thenputting the A-7550 into the reference mode whichmakes this stored trace the zero reference. Theprocedure for doing so is outlined below.

(A) Setting Zero dB Insertion loss ReferenceSet the A-7550 for the desired frequency andbandwidth. Connect the output and input leadstogether through a female barrel connector (UG 29-N or UG 914 -BNC) and proceed as follows:

a) Make sure that the unit is in “LIVE” mode.

b) From the Mode Menu, “STORE” the trace.

c) Switch to the Display Menu and select“REF”. The trace should appear at the 0 dBlevel.

(B) Setting Zero dB Return Loss ReferenceSet the A-7550 for the desired frequency andbandwidth. Connect the Return Loss Bridge to theA-7550 but leave the LOAD port open. Repeatsteps a, b, and c above. See Figure 22.

Bridge

AnalyzerInput

GenerateOutput

TUNE

+30

+20

+10

0

-10

-20

-30

1

53 4

6

2

Figure 29: Tuning for maximum return loss.

Bridge

Any goodquality50 ohm

load

DualVHF

Isolator

Loads that willbe used during

actual operation

AnalyzerInput

GenerateOutput

TUNE

+30

+20

+10

0

-10

-20

-30

1

53 4

6

2

Figure 28: Tuning for maximum return loss.


1) Set the A-7550 for 10 dB per division and set azero dB return loss reference as outlined inparagraph B.

2) With the equipment connected as in Figure 28,adjust tuning capacitor #1 for maximum returnloss at the desired center frequency.

3) Reversing the bridge and load connections asshown on Figure 29; adjust capacitor 2 formaximum return loss at the desired center fre-quency.

4) Set the A-7550 for 2 dB per division verticalscale and set a zero dB insertion loss referenceas outlined in paragraph A.

5) Connect the A-7550 to the isolator as shown inFigure 30. Adjust capacitors 3 and 4 for a cen-tered and symmetrical response.

6) Set the A-7550 for 10 dB per division and resetthe zero dB insertion loss reference per para-graph A.

7) Connect the equipment as shown in Figure 31and adjust capacitor 5 for maximum attenuation(reverse isolation). Be sure to remove the out-put load as this allows the observation of theisolation produced by a single section.

8) Reconnect the output load and disconnect theinput load as shown in Figure 32. Adjust capac-

AnalyzerInput

GenerateOutput

TUNE

RF

LoadRemoved

+30

+20

+10

0

-10

-20

-30

1

53 4

6

2

Figure 31: Tuning for reverse isolation.

AnalyzerInput

GenerateOutput

TUNE

+6

+4

+2

0

-2

-4

-6

1

53 4

6

2

RF

Figure 30: Tuning for passband symmetry.


itor 6 for maximum attenuation (reverse isola-tion). Then reconnect the input load.

9) Repeat steps 1 through 8. The isolator is nowready to be put back in service.

MAINTENANCEBecause T-Pass transmit combiners are com-posed of passive components, they will continue tooperate without any maintenance for years andthere is no recommended maintenance period.However, we do feel that it is wise to check com-biner performance by measuring channel loss peri-odically and this may be done at any convenienttime along with other radio system maintenance.

AnalyzerInput

GenerateOutput

TUNE

RF

LoadRemoved

+30

+20

+10

0

-10

-20

-30

1

53 4

6

2

Figure 32: Tuning for reverse isolation.



UHF Single Junction Circulators and Isolators

Frequency Range (MHz)

406-430 81-65-15-00 81-65-15-20 81-65-15-50 81-65-15-60 81-65-15-100

450-470 81-70-15-00 81-70-15-20 81-70-15-50 81-70-15-60 81-70-15-100

470-490 81-71-15-00 81-71-15-20 81-71-15-50 81-71-15-60 81-71-15-100

490-512 81-72-15-00 81-72-15-20 81-72-15-50 81-72-15-60 81-72-15-100

510-530 81-75-15-00 81-75-15-20 81-75-15-50 81-75-15-60 81-75-15-100

Number of Junctions 1

Junction Type Distributed Parameter

Max Continuous Input Power 250 W

RF Load Model Number None 82-01-05 82-01-16 82-01-17 82-01-15

Continuous RF Load Power None 5 W 25 W 60 W 100 W

Isolation Bandwidth 1% of center frequency

Typical Insertion Loss 0.35 dB

Max Insertion Loss 0.4 dB

Peak Reverse Isolation >30 dB

Min Reverse Isolation >25 dB

Nominal Impedance 50 ohm

Min Return Loss (VSWR) 20 dB (1:22: 1)

Temperature Range -30 to +60 Celsius

Connectors, Input/Output/Load N

Dimensions, HxWxD, inches 4.19x3.99x1.78 5.22x3.99x1.78 8.97x3.99x1.78 10.09x3.99x1.78 10.09x3.99x1.90

Dimensions, HxWxD, mm 106x101x45 133x101x45 228x101x45 256x101x45 256x101x48

Weight, lb (Kg) 1.40 (0.64) 1.58 (0.72) 2.05 (0.93) 2.68 (1.21) 3.41 (1.55)

UHF Dual Junction Circulators and Isolators

Frequency Range (MHz)

406-430 81-65-25-00 81-65-25-20 81-65-25-50 81-65-25-60 81-65-25-100

450-470 81-70-25-00 81-70-25-20 81-70-25-50 81-70-25-60 81-70-25-100

470-490 81-71-25-00 81-71-25-20 81-71-25-50 81-71-25-60 81-71-25-100

490-512 81-72-25-00 81-72-25-20 81-72-25-50 81-72-25-60 81-72-25-100

510-530 81-75-25-00 81-75-25-20 81-75-25-50 81-75-25-60 81-75-25-100

Number of Junctions 2

Junction Type Distributed Parameter

Max Continuous Input Power 250 W

RF Load Model Number None 82-01-05 82-01-05 82-01-05 82-01-05

82-01-05 82-01-16 82-01-17 82-01-15

Continuous RF Load Power None 5/5 W 5/25 W 5/60 W 5/100 W

Isolation Bandwidth 1% of center frequency

Typical Insertion Loss 0.7 dB

Max Insertion Loss 0.8 dB

Peak Reverse Isolation >60 dB

Min Reverse Isolation >50 dB

Nominal Impedance 50 ohm

Min Return Loss (VSWR) 20 dB (1:22: 1)

Temperature Range -30 to +60 Celsius

Connectors, Input/Output/Load N

Dimensions, HxWxD, inches 4.19x8.75x1.78 5.22x8.75x1.78 8.97x8.75x1.78 10.09x8.75x1.78 10.09x8.75x2.9

Dimensions, HxWxD, mm 106x220x45 133x220x45 228x220x45 256x220x45 256x220x48

Weight, lb (Kg) 2.95 (1.34) 3.13 (1.42) 3.59 (1.63) 4.22 (1.92) 4.95 (2.25)


Voltage Ratio

PowerRatio dB Voltage

RatioPowerRatio

1 1 0 1 1

0.989 0.977 0.1 1.012 1.0230.977 0.955 0.2 1.023 1.0470.966 0.933 0.3 1.035 1.072

0.955 0.912 0.4 1.047 1.0960.944 0.891 0.5 1.059 1.1220.933 0.871 0.6 1.072 1.148

0.923 0.851 0.7 1.084 1.1750.912 0.832 0.8 1.096 1.2020.902 0.813 0.9 1.109 1.23

0.891 0.794 1 1.122 1.2590.881 0.776 1.1 1.135 1.2880.871 0.759 1.2 1.148 1.318

0.861 0.741 1.3 1.161 1.3490.851 0.724 1.4 1.175 1.380.841 0.708 1.5 1.189 1.413

0.832 0.692 1.6 1.202 1.4450.822 0.676 1.7 1.216 1.4790.813 0.661 1.8 1.23 1.514

0.804 0.646 1.9 1.245 1.5490.794 0.631 2 1.259 1.5850.785 0.617 2.1 1.274 1.622

0.776 0.603 2.2 1.288 1.660.767 0.589 2.3 1.303 1.6980.759 0.575 2.4 1.318 1.738

0.75 0.562 2.5 1.334 1.7780.741 0.55 2.6 1.349 1.82

0.733 0.537 2.7 1.365 1.8620.724 0.525 2.8 1.38 1.9050.716 0.513 2.9 1.396 1.95

0.708 0.501 3 1.413 1.9950.7 0.49 3.1 1.429 2.042

0.692 0.479 3.2 1.445 2.089

0.684 0.468 3.3 1.462 2.1380.676 0.457 3.4 1.479 2.1880.668 0.447 3.5 1.496 2.239

0.661 0.437 3.6 1.514 2.2910.653 0.427 3.7 1.531 2.3440.646 0.417 3.8 1.549 2.399

0.638 0.407 3.9 1.567 2.4550.631 0.398 4 1.585 2.5120.624 0.389 4.1 1.603 2.57

0.617 0.38 4.2 1.622 2.630.61 0.372 4.3 1.641 2.6920.603 0.363 4.4 1.66 2.754

0.596 0.355 4.5 1.679 2.8180.589 0.347 4.6 1.698 2.8840.582 0.339 4.7 1.718 2.951

0.575 0.331 4.8 1.738 3.020.569 0.324 4.9 1.758 3.09

0.562 0.316 5 1.778 3.1620.556 0.309 5.1 1.799 3.2360.55 0.302 5.2 1.82 3.311

0.543 0.295 5.3 1.841 3.3880.537 0.288 5.4 1.862 3.4670.531 0.282 5.5 1.884 3.548

0.525 0.275 5.6 1.905 3.6310.519 0.269 5.7 1.928 3.7150.513 0.263 5.8 1.95 3.802

0.507 0.257 5.9 1.972 3.890.501 0.251 6 1.995 3.9810.496 0.246 6.1 2.018 4.074

0.49 0.24 6.2 2.042 4.1690.484 0.234 6.3 2.065 4.2660.479 0.229 6.4 2.089 4.365

0.473 0.224 6.5 2.113 4.4670.468 0.219 6.6 2.138 4.5710.462 0.214 6.7 2.163 4.677

0.457 0.209 6.8 2.188 4.7860.452 0.204 6.9 2.213 4.8980.447 0.2 7 2.239 5.012

0.442 0.195 7.1 2.265 5.1290.437 0.191 7.2 2.291 5.2480.432 0.186 7.3 2.317 5.37

0.427 0.182 7.4 2.344 5.4950.422 0.178 7.5 2.371 5.623

0.417 0.174 7.6 2.399 5.7540.412 0.17 7.7 2.427 5.8880.407 0.166 7.8 2.455 6.026

0.403 0.162 7.9 2.483 6.1660.398 0.159 8 2.512 6.310.394 0.155 8.1 2.541 6.457

0.389 0.151 8.2 2.57 6.6070.385 0.148 8.3 2.6 6.7610.38 0.145 8.4 2.63 6.918

0.376 0.141 8.5 2.661 7.0790.372 0.138 8.6 2.692 7.2440.367 0.135 8.7 2.723 7.413

0.363 0.132 8.8 2.754 7.5860.359 0.129 8.9 2.786 7.7620.355 0.126 9 2.818 7.943

0.351 0.123 9.1 2.851 8.1280.347 0.12 9.2 2.884 8.3180.343 0.118 9.3 2.917 8.511

0.339 0.115 9.4 2.951 8.710.335 0.112 9.5 2.985 8.9130.331 0.11 9.6 3.02 9.12

0.327 0.107 9.7 3.055 9.3330.324 0.105 9.8 3.09 9.550.32 0.102 9.9 3.126 9.772

Voltage Ratio

PowerRatio dB Voltage

RatioPowerRatio

Power Ratio and Voltage Ratio to DecibelConversion Chart

Example: Given a gain of +9.1 dB or a loss of -9.1 dB

Loss or Gain Power Ratio Voltage Ratio

+9.1 dB 8.128 2.851

-9.1 dB 0.123 0.351

- dB +- dB +


500

400

300

250

200

150

125

100

75

50

50 75 100 125 150 200 250 300 400 500

7.0

6.5

6.0

5.5

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

.50

.25

The graph below offers a convenient means of determining the insertion loss of filters, duplexers, multicouplers and related products. The graph on the back page will allow you to quickly determine VSWR. It should be remembered that the field accuracy of wattmeter readings is subject to considerable variance due to RF connector VSWR and basic wattmeter accuracy, particularly at low end scale readings. However, allowing for these variances, these graphs should prove to be a useful reference.

POWER IN/OUTVS

INSERTION LOSS

INSERTION LOSS (dB)

INP

UT

PO

WE

R (

Wat

ts)

OUTPUT POWER (Watts)FOR LOWER POWER LEVELS

DIVIDE BOTH SCALESBY 10 (5 TO 50 WATTS)


500

400

300

200

100

50

40

30

20

10

5.0

4.0

3.0

2.0

1.0

0.5

40 20 10 8.0 6.0 4.0 2.0 1.0 0.8 0.6 0.4 0.2

1.1:1

1.15:1

1.2:1

1.25:1

1.3:1

1.4:1

1.5:1

1.6:1

1.8:1

2.0:1

2.5:1

3.0:1

FO

RW

AR

D P

OW

ER

(W

atts

)

REFLECTED POWER (Watts)FOR OTHER POWER LEVELS

MULTIPLY BOTH SCALESBY THE SAME MULTIPLIER

POWER FWD./REV.VS

VSWR

VSWR


NOTES


Power Conversion ChartdBm to dBw to Watts to Volts

dBm dBw Watts Volts 50Ω80 50 100kW 2236

75 45 31.6 kW 1257

70 40 10.0 kW 707

65 35 3.16 kW 398

60 30 1000 224

55 25 316 126

50 20 100 70.7

45 15 31.6 39.8

40 10 10.0 22.4

38 8 6.31 17.8

36 6 3.98 14.1

34 4 2.51 11.2

32 2 1.58 8.90

30 0 1.00 7.07

29 -1 0.79 6.30

28 -2 0.63 5.62

27 -3 0.50 5.01

26 -4 0.40 4.46

25 -5 0.32 3.98

24 -6 0.25 3.54

23 -7 0.20 3.16

22 -8 0.16 2.82

21 -9 0.13 2.51

20 -10 0.10 2.24

19 -11 79 mW 1.99

dBm dBw Watts Volts 50Ω18 -12 63 mW 1.78

17 -13 50 mW 1.58

16 -14 40 mW 1.41

15 -15 32 mW 1.26

14 -16 25 mW 1.12

13 -17 20 mW 1.00

12 -18 16 mW 0.890

11 -19 13 mW 0.793

10 -20 10 mW 0.707

9 -21 7.9 mW 0.630

8 -22 6.3 mW 0.562

7 -23 5.0 mW 0.501

6 -24 4.0 mW 0.446

5 -25 3.2 mW 0.398

4 -26 2.5 mW 0.354

3 -27 2.0 mW 0.316

2 -28 1.6 mW 0.282

1 -29 1.3 mW 0.251

0 -30 1.0 mW 0.224

-5 -35 316 uW 0.126

-10 -40 100 uW 0.071

-15 -45 31.6 uW 0.040

-20 -50 10 uW 0.022

-25 -55 3.16 uW 0.013

-30 -60 1 uW 0.007


Free Space Path Loss Estimator

Frequency in MHz

50 150 170 450 500 800 900

Pat

h L

eng

th (

mile

s)

0.1 50.58 60.12 61.21 69.66 70.58 74.66 75.68

0.25 58.54 68.08 69.17 77.62 78.54 82.62 83.64

0.5 64.56 74.10 75.19 83.64 84.56 88.64 89.66

1 70.58 80.12 81.21 89.66 90.58 94.66 95.68

2 76.60 86.14 87.23 95.68 96.60 100.68 101.71

3 80.12 89.66 90.75 99.21 100.12 104.20 105.23

4 82.62 92.16 93.25 101.71 102.62 106.70 107.73

5 84.56 94.10 95.19 103.64 104.56 108.64 109.66

6 86.14 95.68 96.77 105.23 106.14 110.22 111.25

7 87.48 97.02 98.11 106.57 107.48 111.56 112.59

8 88.64 98.18 99.27 107.73 108.64 112.72 113.75

9 89.66 99.21 100.29 108.75 109.66 113.75 114.77

10 90.58 100.12 101.21 109.66 110.58 114.66 115.68

12 92.16 101.71 102.79 111.25 112.16 116.25 117.27

14 93.50 103.04 104.13 112.59 113.50 117.58 118.61

16 94.66 104.20 105.29 113.75 114.66 118.74 119.77

18 95.68 105.23 106.31 114.77 115.68 119.77 120.79

20 96.60 106.14 107.23 115.68 116.60 120.68 121.71

30 100.12 109.66 110.75 119.21 120.12 124.20 125.23

40 102.62 112.16 113.25 121.71 122.62 126.70 127.73

50 104.56 114.10 115.19 123.64 124.56 128.64 129.66

Formula: Path Loss (dB) = 36.6 + 20 log (MHz) + 20 log (miles)


Return Loss vs. VSWR

Return Loss VSWR

30 1.06

25 1.11

20 1.20

19 1.25

18 1.28

17 1.33

16 1.37

15 1.43

14 1.50

13 1.57

12 1.67

11 1.78

10 1.92

9 2.10

Watts to dBm

Watts dBm

300 54.8

250 54.0

200 53.0

150 51.8

100 50.0

75 48.8

50 47.0

25 44.0

20 43.0

15 41.8

10 40.0

5 37.0

4 36.0

3 34.8

2 33.0

1 30.0

dBm = 10log P/1mWWhere P = power (Watt)

Insertion LossInput Power (Watts)

50 75 100 125 150 200 250 300

3 25 38 50 63 75 100 125 150

2.5 28 42 56 70 84 112 141 169

2 32 47 63 79 95 126 158 189

1.5 35 53 71 88 106 142 177 212

1 40 60 79 99 119 159 199 238

.5 45 67 89 111 134 178 223 267

Output Power (Watts)

Inse

rtio

n Lo

ss

Free Space LossDistance (miles)

.25 .50 .75 1 2 5 10 15

150 68 74 78 80 86 94 100 104

220 71 77 81 83 89 97 103 107

460 78 84 87 90 96 104 110 113

860 83 89 93 95 101 109 115 119

940 84 90 94 96 102 110 116 120

1920 90 96 100 102 108 116 122 126

Free Space Loss (dB)Free space loss = 36.6 + 20log D + 20log F

Where D = distance in miles and F = frequency in MHz

Freq

uenc

y (M

Hz)

8625 Industrial Parkway, Angola, NY 14006 Tel: 716-549-4700 Fax: 716-549-4772 [email protected] www.bird-technologies.com

Bird 7-9120 Multicoupler

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Transcript of Bird 7-9120 Multicoupler