Transcript www.rarchams.org

Vintage Homebrew
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Setting the stage
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Technology / economics / history
Examples
Vintage homebrew hints and tips
Setting the Stage
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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
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Late 50s -> HF bands choked with AM signals drove change to SSB
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Today -> PC in every shack (and most rigs)
Evolution of Ham Radio
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Teens/1920s -> Lots of experimentation. Heavy techie emphasis
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1930s -> Maturing technology allowed non-techie interests
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Belong to a club, public service, rag chewing, Contesting, DX, more
1930s - 1960s -> most technology and construction techniques could be
replicated in home workshop
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Homebrew stations common
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State of the art construction articles in magazines and books
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Many companies sold parts and and kits
Why Homebrew?
Why not just buy a rig?
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High cost of store bought gear vs homebrew
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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
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Changed over past several decades
Peer pressure
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Homebrew stations featured in magazines
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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
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Two tube regen common in many
late 20s/early 30s shacks
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Breakthru late teens invention
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Tricky to use
Based on 1928 QST articles
Covers 80, 40 and 20 mtrs with
plug-in coils
Limited usefulness today
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Controls interact
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Easily overloaded
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Hum above 5MHz
Early 1930's Transmitter
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Tuned plate/Not Tuned grid (TNT)
CW Transmitter
Popular late 20s/early 30
Used broadcast rcvr parts including
tubes
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Coils for 80 and 40
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Runs about 10 watts
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Has personality but usable
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Microphonic
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No bandspread/calibration
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Hand Capacity
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Exposed high voltage
I've made several contacts using it
1940 Portable Transmitter
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Hero of Hallettsville
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Used to provide emergency
communications during June
1940 south Texas flood
QSL - 40 design
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Several versions in QST 19381941
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Ran 5-100 watts
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6L6 / xtal controlled / CW / QSL
card size
Original / as found
Three Tube Superhet
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Based on 1941 QST Design
Step beyond 2 tube regen
Converter stage followed by
1700KHz regenerative IF
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Plug-in coils for 80 and 40 mtrs
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Primitive crystal filter
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Headphones only
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Similar designs in ARRL Handbook
thru 1965
Works surprisingly well
Two Tube 1940 Transmitter
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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
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Novice license introduced in 1951
Initially only HF privilege was 80
mtr cw
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1951 QST designs
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Two tube regenerative receiver
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One tube 10 watt transmitter
Station needed to be inexpensive
and easy to build
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Wooden chassis
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Common parts
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Homemade coils
3 to 4 watts output
Separate power supply
Works but challenge to make
contacts
Late 50s Mobile AM Transmitter
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60-90 watt AM transmitter
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Appears to be late 50s design
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Easily fit under 1950s dashboard
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Probably used with car radio and
SW converter
Changing bands/freq while moving
would have been dangerous
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Change crystal
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Peak osc stage
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Dip and load final
HBR-16
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Popular/classic receiver of late
50s thru late 60s
Various versions - > 30 articles in
QST
Mine built by David Hoffman,
W0FGV, in Northfield, MN
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16 tubes
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Double conversion
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Band change required changing
three coils
Mine had a resident mouse
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Ruined several tube sockets
Work in process
Paddles / Bug / Key
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Not all homebrew is Electronic
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Keyer paddles
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Miniature bug
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Straight key
Construction Articles and Help
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Current magazines
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Electric Radio: http://www.ermag.com/
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QST
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CQ
Web sites
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Mail reflectors
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Google what you are looking for: http://www.google.com
mailman.qth.net Mailing Lists: http://mailman.qth.net/mailman/listinfo
Reprints (including Radio Handbooks and QST magazine)
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Lindsay Publications http://www.lindsaybks.com/
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Back issues of QST on CD-ROM
http://www.arrl.org/catalog/index.php3?category=CD-ROMs
Parts
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Start with a list, shoe box, patience
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Hardware store for screws, nuts, bolts, gun blueing
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Friends
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Swapmeets
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June 3M swapmeet
Mail order
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Antique Electronic Supply http://www.tubesandmore.com
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Bob's Antique Radio & Electronics http://www.radioantiques.com/
eBay
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Can be expensive
Safety
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Voltages present can be lethal
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Power down and discharge caps
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Know where the high voltage is
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One hand in the pocket
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Add safety features
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Fused 3 wire line cord
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No exposed high voltages
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AC line isolation transformer
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Headphone isolation transformer
Getting on the Air
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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/