[CQ-Contest] SO2R antenna distance

[Barry]

Depends on power level and how you supress the other signal (stubs, 
bandpass filters or both. I have both). My 402CD is 9 ft from my high 
TH7 and no problems barefoot, and can get within 10-15 Khz of the 2nd 
harmonic on 20 (eg., 7005/14010). When on 20-10m, I have a TH7 at 
40 ft (lower part of stack) and one at 25 ft on same tower. No problems 
at all, except when on the second harmonic (eg., 14005/28010).

However...
You may want to rethink the vertical. I tried that, first, using a Hygain 
DX77 multiband vertical. A dummy load would have been just as good! I 
compared the vertical with a TH7 at 25 ft, and the TH7 was 5-6 S units 
better than the vertical. One potential problem you may have - I 
modeled the entire system, with different tribanders, before deciding 
what to do (I didn't want to install a second tower). I recall that I 
modeled C31XR's and the interactions between antennas were awful. 
With TH7s they were minimal. That's why I went with TH7s. As you 
already have a C4, you may want to consider another C4 at 30 ft for the 
second radio, but model it first to check for interactions.
Barry W2UP

On 14 Sep 2002 Dave LaBat wrote:

> Doing some basic planning. How far away would those of you operating 
> SO2R consider the minimum distance between the main antenna (Force 12 C4 
> at 60 feet) to a vertical? Are there any good resources on the web for 
> this part of a SO2R? All the hits on google referred to software and 
> inside the shack issues. I think I want to figure out if the antennas 
> can be placed appropriately before I look at the inside issues. Thanks 
> in advance Dave KØXH
> 
> _______________________________________________
> CQ-Contest mailing list
> CQ-Contest at contesting.com
> http://lists.contesting.com/mailman/listinfo/cq-contest