The New 630m Amateur Band

Rudy SevernsN6LF, WD2XSH/20

n6lf@arrl.net, www.antennasbyn6lf.com

A New Amateur BandAfter many years on the air using experimental

licenses and intense politicking, at the 2012 World Radio Conference (WRC) amateurs were allocated a new MF band: 472-479 kHz.

Telecom authorities in various countries are now in the process of authorizing their amateurs to use the band.

Many Europeans, VE, VK, ZL and even XV are on the air and we’re bugging the FCC to move!

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630 m Band• 472-479 kHz. • Emissions: CW and digital modes• Radiated power limited to 5W EIRP (Effective

Isotropic Radiated Power)• No limitations on transmitter power or

antenna size. i.e. you can use a small transmitter with a large antenna or a high power transmitter with a small antenna.

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Common Perceptions!• A 7 kHz band is too narrow to be of use! The

QRM will kill you!• At such a low frequency with only 5W you can’t

be heard down the block!• The manmade and natural noise levels are so

high you can’t hear anything!• It’s impossible for amateurs on city lots to erect

an effective antenna.• No amateur equipment transmits on 630m.

• None of this is true!

Why go to 630m?

• If you’re a bit tired of the same old stuff 630m is a fresh challenge:– Very different propagation– New very narrow digital modes– But also the oldest mode – CW– Station-computer integration– Receiving and transmitting equipment– Antennas– Boat anchor resurrection

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Acknowledgements

• Much of the material presented here has been excerpted from the presentations of other amateurs:

• Fritz Raab W1FR, WD2XSH/14• John Langridge KB5NJD, WG2XIQ• Neil Klagge, W0YSE,WG2XSV

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500 kHz History•Maritime CW calling/distress frequency since 1906•415-495 kHz commercial ship-ship and ship-shore working frequencies also Navy•Rich traditions and history•Amateurs banned for >100 years!• Automated satellite reporting adopted in 1980s• CW and monitoring of 500 kHz ceased in 1990s

• 500 kHz now unused except by museum stations

The spectrum below the BC band

Navigational telex

ARRL experimental group

• First operation September 2006, W1FR experiment coordinator

• Originally 23 stations were licensed (WD2XSH/1 thru WD2XSH/23)

• Frequency allocation: 495-510 kHz, 20W ERP• Ultimately it was expanded to 45 licensees with

added frequencies: 461-478 kHz• This operation and that of many others provided

the ammunition for the WRC allocation battle!9

ARRL experimental stations

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WD2XSH CW QSO’s

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CW DX reception reports

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V73

CW beacon reception reports /20

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WD2XSH/14 (W1FR)

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Original WD2XSH/20 (N6LF)

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Latest WD2XSH/20 (N6LF)

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Latest WD2XSH/20 (N6LF)

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Filters!

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Boat anchors at N6LF

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WD2XSH/5 (KW1I)

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RBA receiver and an ART13 transmitter

WD2XSH/9 (W2ILA)

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Maritime reserve XMTR

WD2XSH/12 (AI8Z)

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HB pair 6146’s

WD2XSH /15 (W5OR)

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SAC H-25 NDB XMTR

Nice but you don’t have to have it!

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MF antenna basics!

• Succinct summary of LF/MF antennas by Woodrow Smith some 65 years ago:

"the main object in the design of low frequency transmitting antenna systems can be summarized briefly by saying that the general idea is to get as much wire as possible as high in the air as possible and to use excellent insulation and an extensive ground system.”

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In order of priority• Make the vertical as tall as you can.• Use as much capacitive top-loading as practical.• Use loading coils with as high a Q as possible.• Put a lot of effort into the ground system, making the

radial density high near the base of the vertical and under the top-loading hat.

• Try to minimize conductor losses by using multiple wires and/or large diameter conductors (tubing!)

• Use high quality insulators, both at the base and at wire ends.

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T and L antennas

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Use the available supports

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Umbrella vertical 1

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Umbrella vertical 2

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WD2XSH/14

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WD2XSH/13 antenna

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WD2XSH/19 antenna

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WD2XSH/6 (W5THT) antenna

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ATU box

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Inside the ATU

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Tuning the ATU

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WD2XSH/20 antenna

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Latest antenna at N6LF

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95’ high, 240’ across, 128 150’ radials on the groundThere’s a very extensive discussion of MF antennas at: www.antennasbyn6lf.com

Antenna poles at N6LF

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Base tuning box

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Tuning-matching inductor

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Poles assembled on the ground

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Pole erected with a crane

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Propagation

• Daytime – ground wave– WG2XIQ range at 1W ERP = about 225 miles on a quiet day

for a typically equipped receive station• Nighttime – sky wave dominates plus some ground

wave– Sky wave can extend thousands of miles

• Behavior similar to bottom of the BC band at 630-meters

• Sometimes there are surprises

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Start by listening…

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Transmission modes

• CW• QRSS – ultra slow CW• WSPR-2 & -15 (weak signal propagation

reporter). SNR down to -30 dB or lower!• 2-way digital modes: BPSK31, JT9, JT65, RTTY,

hellschriber and a wide variety of new modes being created and tested almost daily!

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WSPR –K1JTWWW.physics.princeton.edu/pulsar/K1JT/wsjt.html

WSPR-2 and -15 is a tool for quantitatively testing propagation between a transmitting station and a receiving station. Typically the WSPR signals are transmitted periodically over a period of many hours with the receiving station recording the decodes and forwarding them on to WSPRnet.org where they are available in the database. Example:

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Timestamp Call MHz SNR Drift Grid Pwr Reporter RGrid km AZ 2014-01-30 17:34 WG2XIQ 0.475666 -17 0 EM12mp 0.05 WG2XXM EM15lj 306 359 2014-01-30 17:36 G3XIZ 0.475700 -29 0 IO92ub 0.5 DD7PC JN49ax 627 108 2014-01-30 17:38 WG2XIQ 0.475666 -17 0 EM12mp 0.05 WG2XXM EM15lj 306 359 2014-01-30 17:40 DL8YCA 0.475782 -11 -1 JO31or 0.01 PI4THT JO32kf 60 338

WSPR Mapping

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WSPR Data

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-30

-25

-20

-15

-10

-5

0

5

2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00

Time [UTC]

SN

R [

dB

]

WE2XPQ WSPR receptionof WD2XSH/20

29 Jan 2014

CW QSO possible

Software audio spectrum analyzers

• Waterfall and spectrum displays– ARGO – I2PHD– Spectran – I2PHD, www.weaksignals.com – Spectrum lab – DL4YHF www.qsl.net/dl4yhf

• These are all freebies!• All these require is an audio signal from your

receiver.• They work with modern or boat anchors rx

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Waterfall displays

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WD2XSH/6 MS, /15 AR and /19 IL

RX antennas

• Use vertical polarization – horizontal antennas tend to be very noisy

• Loops– vertical loops, shielded or not, a quad loop works well– K9AY terminated loops

• E-probe (very short vertical) with or without amp• Existing HF Antennas – dipole, random end fed wires,

etc.• Beverages and “Snakes” (BOG)• Phased arrays of E-probes

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Testing your receiver

• NAVTEX– Maritime WX reports– 518 KHz and 490 KHz– RTTY

• Non-directional beacons (NDB)– Low power, omnidirectional– Numerous– http://fivegulf.com/ndb/

• Part 5 Stations– CW– PC based digital modes – WSPR, MSK, OPERA

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THE QUEST CONTINUES ...

Amateurs commercial interests

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Resources 1 • Compiled by WA3ETD/WG2XKA with minor editing by N6LF.• http://www.500kc.com : Main Web Presence for WD2XSH

ARRL MF Experiment. Lots of links and personal web sites from heavy hitters.

• http://www.w1vd.com : Jay Rusgroves MF/LF Site - gear and info. Jay is the guy behind Advanced Antenna Research (AAR). Good stuff and a fantastic craftsman.

• http://www.500kc.com/W0RPK_Report/W0RPK_Report.htm : The updated daily "action“ report from previous day MF activity. Also contains live links to many personal Ham/MF websites. Check this one for sure! Includes DX records...

• http://members.shaw.ca/ve7sl/ : Details on broadband MF/HF receive loops and preamps. Good Stuff, easy to build.

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Resources 2• http://www.w8ji.com/radiation_resistance.htm : Details

regarding small antenna efficiency and calculations.• http://www.strobbe.eu/on7yd/136ant : A VERY detailed and

heavy analysis of LF/ MF antenna design. Hours of valuable reading. Don't be discouraged when he says it won't work…

• http://www.russthom.com/ndb : Current list of MF Navigation Beacons in the US…

• http://www.dxinfocentre.com/ndb.htm : THE PREMIER list of MF Beacons (Hepburn) continuously updated, very organized. Use this to correlate calls and frequency.

• http://www.gw3uep.ukfsn.org/index.htm : Rog's 100W TX and many cool designs. Homebrew Heaven...don't miss. Check "MF Test Gear".

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Resources 3

• http://toroids.info/T37-2.php : Toroid specs and inductance/turn calculator- Get your Al values here. (Kits 'n Parts site)

• http://g3xbm-qrp.blogspot.com : Everything MF and more. Guy never sleeps! There is no way Roger has a life outside his garden...currently into EARTH ANTENNA systems.

• http://www.antennasbyn6lf.com : 2009/13 series of QEX articles on ground system experiments and analysis. Articles on 630m antennas. Required reading!

• http://www.radiomarine.org/#pab1_12 : Fun site dedicated to old-time marine MF.

• http://www.dl5swb.de/html/mini_ring_core_calculator.htm ID your mystery toroid.

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Resources 4• http://www.electronics-tutorials.com/filters/trap-filter.htm

Deep traps for our transmitters - 2nd and 3rd of 475 right in the AM BCB and we can't have that! Cap across coil, easy. Well, a spectrum analyzer sure helps.

• http://w7iuv.com/: Hard core guy way out west. Check out his MF preamp.

• http://www.cliftonlaboratories.com/ Jack Smith - massive line of preamps, filters,active antenna. Plus a wealth of analysis, reviews and tech talk. MF oriented. Includes improved LPF for the Jackson Harbor $14 up-converter. Fun spot on the net.

• http://wb9kzy.com/ham.htm Jackson Harbor Press, home of the $14 up-converter. You get both a 4 and 10 mHz

crystal, he's not making much on this unit.

• WG2XKA@gmail.com John sells the 20W TX converter as a complete kit with silk-screened PCB, available with 3.2 or 4.0 MHz I-F crystal. Optional GPS 10 MHz input.

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Software/Hardware Resources• http://aade.com/filter.htm Filter design and analysis package by the maker of the AADE L/C

meter.

• http://wsprnet.org/drupal/ WSPR automated beacon reporting system

• http://tonnesoftware.com/svcfilter.html : Really good filter design, using standard values with analysis and Monte Carlo.

• http://www.weaksignals.com/ by I2PHD, home for Spectran and ARGO weak signal viewers - sound card based, MUST HAVE...

• http://www.hdsdr.de/ Home of HDSDR package, my favorite, works best with the ensemble II LF receiver. Based upon WINRAD system, now free.

• http://fivedash.com/ Tony Parks SOFTROCK page. Get your Ensemble II. Also links to Yahoo Softrock users group. Lots of really tiny toroids to wind.

• http://www.qsl.net/zl1bpu/CMSK/cmsk.htm : CMSK Software

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