“kitchen sink” radio ham radio fun without complexity roger g3xbm
TRANSCRIPT
“Kitchen Sink” Radio
Ham radio fun without complexity
Roger G3XBMwww.g3xbm.co.uk
Tonight
• My approach• Homebrew techniques• Ideas for homebrew fun• Useful links• Good kits• Good value commercial rigs
My Ethos
• Modest power
• Simple equipment
• Simple antennas
• Small is beautiful
• Simplicity is elegance
• Don’t waste money
Homebrew Approach
Bursts of energy – long gaps without building much
• Go for projects that will get finished• PCBs not required for “one offs”• Projects that don’t need lots of test gear.• Go for good kits• Hasn’t got to be amateur radio related.• Use the gear you make/own.
Components Choice
• Ugly construction
• Discrete parts
• VXO/crystal controlled
• Standardise on parts: 2N3904/6, MPF102, T50-2, T50-6, 0.1u, 10u, 1k, 10k etc
• Re-use parts
• Recycle boxes
The Humble Crystal Set• Simplest radios to get going
• Possible to hear real BC DX on HF
• More to them than you might think
• Amateur band DX reception possible
• -55dBm
Single FET transceiver• Sensitive, stable, non-fiddly, regen RX
• 1 active device
• Stable, crystal controlled, TX
• 14 parts !
Kitten 10m CW transceiver
Pipit derived cct.
0.5W RF out
0.5uV sens.
Full break-in
25kHz VXO
5 transistors
Homebase 10 Antenna
• Simple horizontal halo for 28MHz
• Low cost, easy to build and tune up
• Works well
70cms Moxon Antenna• Made in 30 mins from a metal coat hanger !• 3-4dB forward gain• 100 degree -3dB points
• Best DX 327kms with 5W
Earth Mode Communications
• Communicating at <10kHz through the ground • Use audio power amps and ground rods• Ranges 0-10kms (typically <1km) • PC based RX/filters & QRSS for greater range
Useful “Simple” LinksHOMEBREW
– GQRP club www.gqrp.com/ – Rick Anderson www.tricountyi.net/~randerse/radios.htm – JF1OZL www.intio.or.jp/jf10zl/ – Harry Lythall web.telia.com/~u85920178/ – Gollum’s Xtal RX
www.oldradioworld.de/gollum/index.html – Hans Summers www.100megsfree2.com/hans/ – N4DKD www.n4dkd.com/ – G3XBM www.g3xbm.co.uk
KITS– Elecraft www.elecraft.com – Small Wonder www.smallwonderlabs.com/– Hendricks QRP www.qrpkits.com/
Elecraft T1 Auto-ATU
• Matches 160-6m
• Instant retune when band changing FT817
• No-hands retune from 80-10m
• 6hrs build
Elecraft K1 4 band CW Transceiver
• Excellent kit in the Heathkit style• 5W on 40, 30, 20,15m • Narrow CW filters• Keyer + memory modes• Auto-ATU• Works well
Future projects
• 500kHz QRP TX
• 10m QRP DSB transceiver
• Improved single FET transceiver
• A DSB Fredbox
• Earthmode comms tests with QRSS
The G3XBM Shack• Fits in corner of spare bedroom
• Homebrew rigs plus FT817 and IC703
• “Lab” in back of the garage
Miracle Whip
• Auto-transformer matched 1.5m whip
• With counterpoise is just 2 S-points (12dB) down on a decent vertical
• DX 11000kms from the bedroom table with 5W SSB!