[UK-CONTEST] 2 Station setup ideas please for CQWW

[Dave Lawley]

Hi Jim

The one question that needs answering (sorry if I missed it) is are you 
going to do Multi Single or Multi Two? I also echo Darren's point, the 
split you suggest doesn't make a great deal of sense.

If you're going to do MS then you can perhaps tolerate a greater degree 
of QRM from time to time, whereas for M2 you need effective filtering so 
that you can run two bands with essentially no QRM (there will always be 
odd spot frequencies where you hear a birdie, and there's a limit to 
what can be done about direct harmonics).

If you're MS then as a minimum you get six toroids, six trimmers and a 2 
  pole 6 way switch and make a set of reject filters, for RX only. If 
your rig has a separate receive path (like most Icoms) then you just put 
it inline, or with a Kenwood or Yaesu you can either put in a relay 
which bypasses it on transmit or put in an override switch.

The problem however, if you don't use bandpass filters, is wideband 
noise from the other transmitter. I endorse Andy's comment about older 
rigs and it so happans that I have a TS830s for sale from a silent key, 
it actually has a much better RX than many more modern rigs - let me 
know if you may be interested.

The way we split bands for some of the Cray Valley M8C operations is to 
run the tribander on 10 and 20 only, and use a homebrew 2el quad on 15. 
Quads are great - easy to make (15m not 20!), as much gain as a 3el 
yagi, work well close to ground and lightweight. All you need are eight 
8ft garden canes, make up the spiders out of aluminium angle.

With this setup, stubs and Dunestar filters we were able to enter Multi 
Two in CQWW SSB last year, with about 30ft horizontal separation between 
tribander and quad, with essentially no QRM.

The magic number for coax stubs is 22ft. This assumes you're using RG213 
or something similar with 66% velocity factor. Start with a 23ft piece 
with a plug on one end. Use an MJF or Autek or similar analyser (I had a 
Palstar for a while, it proved utterly useless and I have sent it back).

Starting at about 6MHz tune higher and find the frequency of minimum 
impedance, from memory on the Autek it typically shows as about 7ohm. 
Note this frequency then do the sums to work out how many inches to snip 
off to get it to 7.05MHz. Say this is 4.5 inches, I would snip off 3.5 
and then re-measure. When making a set of stubs the shack floor ends up 
littered with little lengths of coax!

22ft open will reject 40m and 15m, and pass 20m and 10m so that's what 
you put on the line to the tribander. 22ft shorted rejects 20m and 10m 
and passes 40m and 15m, so one goes on the quad and a second one goes on 
the 40m dipole. You can test the stubs in the shack, the 'pass' stub 
should have no effect on received signal and will not affect the SWR. 
The 'reject' stub will make the band go almost completely dead - the 
effect is very impressive.

Working on the same lines you can make stubs for 40 80 and 160. I always 
tape the ends of open stubs with red tape, the ends of closed stubs with 
yellow/green tape, and coil up the spare coax and fix with cable ties. 
Mark the stubs so you know which are which, and be careful of cheapo 
PL259 tee connectors - they can fail suddenly. Hunt out the decent 
variety or make your own junctions.

HTH

Dave G4BUO