Vintage Homebrew
● Setting the stage Technology / economics / history
● Examples● Vintage homebrew hints and tips
Setting the Stage
● Teens/1920s -> Almost everything was experimental. Very little store bought ham radio equipment available
● 1930 -> economics forced rigs to be simple and share a lot of technology with consumer radios
● Late 40s , Early 50s -> rigs reflected WWII experience and military surplus equipment/parts available
● Late 50s -> HF bands choked with AM signals drove change to SSB
● Today -> PC in every shack (and most rigs)
Evolution of Ham Radio
● Teens/1920s -> Lots of experimentation. Heavy techie emphasis
● 1930s -> Maturing technology allowed non-techie interests
● Belong to a club, public service, rag chewing, Contesting, DX, more● 1930s - 1960s -> most technology and construction techniques could be
replicated in home workshop
● Homebrew stations common● State of the art construction articles in magazines and books● Many companies sold parts and and kits
Why Homebrew?Why not just buy a rig?
● High cost of store bought gear vs homebrew
Total Cost includes Manufacturing Cost plus Parts Cost● Point to Point wiring● Hand built/tested● Generic/Commodity parts
● Available time vs cost of store bought gear
Changed over past several decades● Peer pressure
Homebrew stations featured in magazines
Techie roots● Homebrew met performance requirements of most hams
Vintage Homebrew
Ham gear built in the late 20s through the 60s by individuals interested in using it. Typically based on
magazine articles with minor enhancements or changes to meet the requirements of the constructor.
Late 20s Receiver
● Two tube regen common in many late 20s/early 30s shacks
Breakthru late teens invention
Tricky to use● Based on 1928 QST articles
● Covers 80, 40 and 20 mtrs with plug-in coils
● Limited usefulness today
Controls interact
Easily overloaded
Hum above 5MHz
Early 1930's Transmitter
● Tuned plate/Not Tuned grid (TNT) CW Transmitter
● Popular late 20s/early 30
● Used broadcast rcvr parts including tubes
● Coils for 80 and 40
● Runs about 10 watts
● Has personality but usable
Microphonic
No bandspread/calibration
Hand Capacity
Exposed high voltage● I've made several contacts using it
1940 Portable Transmitter
● Hero of Hallettsville
Used to provide emergency communications during June 1940 south Texas flood
● QSL - 40 design
Several versions in QST 1938-1941
Ran 5-100 watts
6L6 / xtal controlled / CW / QSL card size
● Original / as found
Three Tube Superhet
● Based on 1941 QST Design
● Step beyond 2 tube regen
● Converter stage followed by 1700KHz regenerative IF
● Plug-in coils for 80 and 40 mtrs
● Primitive crystal filter
● Headphones only
● Similar designs in ARRL Handbook thru 1965
● Works surprisingly well
Two Tube 1940 Transmitter
● Many classic 6L6 transmitters hard on crystals and tubes
● Gentler design based on a 1940 10 watt AM/CW transmitter
● 6J5 crystal oscillator driving a 6L6 final
● Plug-in coils for 80 and 40
● Nice match for the three tube superhet
1951 Novice Station
● Novice license introduced in 1951
● Initially only HF privilege was 80 mtr cw
● Station needed to be inexpensive and easy to build
Wooden chassis
Common parts
Homemade coils
● 1951 QST designs
● Two tube regenerative receiver
● One tube 10 watt transmitter
3 to 4 watts output● Separate power supply
● Works but challenge to make contacts
Late 50s Mobile AM Transmitter
● 60-90 watt AM transmitter
● Appears to be late 50s design
● Easily fit under 1950s dashboard
● Probably used with car radio and SW converter
● Changing bands/freq while moving would have been dangerous
Change crystal
Peak osc stage
Dip and load final
HBR-16
● Popular/classic receiver of late 50s thru late 60s
● Various versions - > 30 articles in QST
● Mine built by David Hoffman, W0FGV, in Northfield, MN
● 16 tubes
● Double conversion
● Band change required changing three coils
● Mine had a resident mouse
Ruined several tube sockets● Work in process
Paddles / Bug / Key
● Not all homebrew is Electronic
● Keyer paddles
● Miniature bug
● Straight key
Construction Articles and Help
● Current magazines
Electric Radio: http://www.ermag.com/
QST
CQ● Web sites
Google what you are looking for: http://www.google.com● Mail reflectors
mailman.qth.net Mailing Lists: http://mailman.qth.net/mailman/listinfo● Reprints (including Radio Handbooks and QST magazine)
Lindsay Publications http://www.lindsaybks.com/
Back issues of QST on CD-ROM http://www.arrl.org/catalog/index.php3?category=CD-ROMs
Parts
● Start with a list, shoe box, patience
● Hardware store for screws, nuts, bolts, gun blueing
● Friends
● Swapmeets
June 3M swapmeet● Mail order
Antique Electronic Supply http://www.tubesandmore.com
Bob's Antique Radio & Electronics http://www.radioantiques.com/ ● eBay
Can be expensive
Safety
● Voltages present can be lethal
● Power down and discharge caps
● Know where the high voltage is
● One hand in the pocket
● Add safety features
Fused 3 wire line cord
No exposed high voltages
AC line isolation transformer
Headphone isolation transformer
Getting on the Air
● Miscellaneous operating / CQs works
● QRP calling frequencies: http://www.njqrp.org/data/qrp_freqs.html
● Vintage Nets / Round tables. Listed in Electric Radio or at http://www.qcwa.org/chapter029-01.pdf
● Antique Wireless Association Vintage Ham Radio Contests: http://www.antiquewireless.org/amrad.htm .
● Classic Exchange or “CX”: http://qsl.asti.com/CX/
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