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Ferrets, rats and crabs…..and CATs too.
Getting the best from a limited QTH
David Aslin G3WGN TARS Meeting August 28th 2015
1961 Introduction to radio 1963 Joined RSGB as SWL A4677 1967 Licensed as G3WGN, aged 16 1967 - 1970 160 & 80 only; home-brew TX 10W; AR88D and
Lafayette KT-320 1970 - 1978 NFDs, GB3MCG; first commercial rig: Yaesu FT505 400W 1978 - 1990 Work, family, work, family… 1990 - 2000 QRP, DX and contests; 80m DXer 2000 - 2010 WJ6O in Silicon Valley; hired gun contest operator 2010 - 2015 G3WGN and M6O Devon; search for DX & contest site
G3WGN background
From This…
G3WGN/Warwickshire 1968
Sshh! don’t mention the Joystick!
…To This…
G3WGNGQRP 5278Cheshire 1978
Elecraft K2 10WHomebrew 1W on 40mLafayette KT-320
…To This…
M6T 1998
…To This…
G3WGN Herefordshire 1998
Yaesu FT1000MP (now with G6GLP!)Heatherlite Explorer then ACOM 2000A
220 countries on 80m in 3 years
Go West young man…
…To This…N6RO 2002
N6RO
…Then This…K6IDX 2000-2010 K6IDX
…and This...WC6H
…and Back Again
G3WGN Spreyton 2015
Escape noise, small garden, lousy site, weather, XYL… TK/G3WGN SV8/G3WGN EU-072 T32C Dartmoor – SOTA High Willhays TX6G E6GG September 15th- 29th 2015
Globetrotting
Successful stations plan antennas as a SYSTEM Optimise what you have:
Pick the right antenna Pick the right feeder Look after your feeder Kill that noise
Lessons learned
Antenna System Design
Ground-mounted Vertical
Feed with 20m Westflex 103 Antenna gain: -2.4dBd Coax loss: -0.32dB System gain: -2.72dBd
Dipole at 9m
Feed with 20m RG58 + another 10m RG58 up the mast
Antenna gain: 0dBd Coax loss: -2.5dB System gain: -2.5dBd
Antenna System Design
Dipole at 9m
Feed with 20m Westflex 103 + 10m W103 up the mast
Antenna gain: 0dBd Coax loss: -0.48dB System gain : -0.48dBd
2 element YAGI at 9m
Feed with 20m RG58 + 10m RG58 up the mast
Antenna gain: 4dBd Coax loss: -2.5dB System gain: +1.5dBd
What’s the terrain like? Model antenna versus height versus direction with HFTA by
N6BV Put the antenna at the optimum height if you can If you need radials, use plenty – they don’t have to be long if
you don’t have space If you have a choice of location match it to the antenna type
Pick the right antenna
Major performance impact: Antenna Support Terrain Feeder Matching Grounding
Minor performance impact (<100MHz): Connectors
Documentation Maintenance
The antenna system
Antennas on the beachVertical Dipole Arrays
17m and 10m at TX6G
Where to next?
E6GG North Coast of Niue
What’s missing?
Where to next?
E6GG North Coast of Niue
What’s missing?
NO BEACH!
Antenna Choices
TX6G Lots of beach – verticals by the sea! Shacks next to the beach Lots of nearby noise sources VDAs for 10 through 20m Elevated quarter waves for 40 and
30m Vertical/inverted-L for 80/160m Pennant for RX
E6GG No beach; 25m high cliffs Shack 140m from sea Low noise site? Dipoles for 10 through 20m, 1.0λ high Elevated quarter waves for 160
through 30m Beverages for RX
Horses for courses
Antenna at home
Folding Hexbeam
2 elements per band 6-10-12-15-17-20mG3TXQ electrical designFolding Antennas DL1LEU manufacturer
Does it work?
2015:220 DXCC entities/countries900 band slots21 countries on 6m
Actually, anything works - 1
150W lightbulbs in phased arrayby Tom Schiller N6BT
Tom is former founder/owner of Force 12 antennas
Actually, anything works - 2
Enjoyment vs antenna typeaccording to N6BT
Don’t waste power or signal Feeder is cheaper and easier than big antennas and can have more gain! Unless you have very short runs or are on 160m, RG58 or Mini-8 are almost never
the right choice: 1950s product, no longer made to MilSpec Poor screening High losses on HF
Modern coax is much better: Aircell 5 or Aircell 7 (Nevada); Airborne 5 or Ultraflex 7 (Martin Lynch) Even better: Westflex 103 (Henry Westlake)
Pick the right feeder
Feeder loss matters
Running 100Watts?Here’s what is at your antenna:
1dB loss (40ft/12m RG58 at 10m)80W2dB loss (160ft/25m RG213 at 10m)63W3dB loss (120ft/36m RG58 at 10m)
50W
Or, if you have 40ft feeder:RG58: 10m band have 80W at the antennaRG213: 10m band have 89W at the antennaW103: 10m band have 95.5W at the antenna
Feeder change brings the cheapest dB you can have!
Take measurements so you can spot changes Inspect regularly Use high quality connectors, properly waterproofed Everything wants to get into your coax
Water Salt Critters
Look after your feeder
Flushed with success at T32C
Rats!
In UK:Squirrels?Pets?Enthusiastic gardeners?
We are trying to optimise SYSTEM performance, not just antenna performance
20dB (S3) of noise makes 1kW seem like 1W Reducing noise by 6dB is like swapping your dipole for a 3 or 4 element
beam Verticals are great for picking up noise, go horizontal at home if you can Don’t let common mode noise ruin your day or DX
Opportunity: W0GJ at the RSGB Convention: Is 3dB worth a divorce?
Kill that noise
‘Electronic smog’ is everywhere, but you can tame (some of) it Feeders don’t only feed signals, they feed noise unless you stop
them Keep noise out with ferrets
At antenna feedpoint At shack entry point On mains cables and interconnects
Dealing with noise
The Reverend Jim K9YCFerret trainer extraordinaire
K9YC ferrite chokes
Use FT240-31 toroids or Type -31 clip-onsPut enough turns on! HF 3-5 LF 5-9+
See Jim’s Cookbook audiosystemsgroup.com/RFI-Ham.pdf
Ian GM3SEKHoney, I shrunk the ferrets!
http://www.ifwtech.co.uk/g3sek/in-prac/inpr1005_ext_v2.pdf
M0PCB version of GM3SEK ferrite choke
Try stuff – you may like it Competing with yourself drives continuous improvement Simple wire antennas work Pick the right antenna for your location Choose the right feeder and look after it Kill that noise If all else fails, operate from somewhere else…
Lessons
What about the CATs?I thought you said there’d be CATs?
CAT – station automation
CAT – Computer Aided Transceiver
Vertical dipole arrays: RadCom December 2014, p34 and http://www.f4bkv.net/antenna-vda.html Folding Antennas Hexbeam: RadCom April 2015, p26 and
www.foldingantenna.com HFTA by N6BV: ARRL Antenna Book 21st-23rd Editions Ferrite chokes:
K9YC: audiosystemsgroup.com/RFI-Ham.pdf K9YC: audiosystemsgroup.com/CoaxChokesPPT.pdf GM3SEK: http://www.ifwtech.co.uk/g3sek/in-prac/inpr1005_ext_v2.pdf
Finding and killing noise: http://www.nccc.cc/pdf/Sep-K9YC-RFI2013.pdf “Everything works” N6BT: http://www.ok1rr.com/index.php/antennas/94-
everything-works
Further Reading
Questions?
Where to next?
E6GG North Coast of Niue
6Gs team that brought you TX6G last year
September 15-29 2015
www.e6gg.com
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