[CQ-Contest] Minimal SO2R -- is spacing enough?

[k8cc]

At 08:46 AM 8/10/01 -0400, Pete Smith wrote:
>I'm contemplating SO2R for the first time.  I have the two radios and a
>decent amount of real estate.  My question, hoping to benefit from others'
>experience -- do I stand a chance of doing this on CW, relying solely on
>polarity diversity, low power on the second radio and distance between
>antennas?  Or should I just assume the worst and plan on bandpass filters?
>For the second radio, I'm thinking of an R-5 or similar vertical, spaced
>about 300 feet from my yagis, running 100 watts.

Pete,

For WRTC 1996 the station assigned to each team had a triband beam and a 
40M dipole.  We were also assigned a set of single-band ICE bandpass 
filters for 40, 20, 15, and 10 meters.  We had two 100W rigs, but only one 
could transmit.  The presumption of this configuration is that one radio 
runs QSOs using the "correct" antenna for that band while the other radio 
searches for multipliers using the "other" antenna.  Antenna and filter 
switching was dictated to be manual.

At our station (W6P) the 40M dipole was only three to four feet below the 
tribander.  Our radios were a pair of IC-765s.  Using the ICE filters we 
had little or no interference problems.  However, the manual filter and 
antenna switching was cumbersome.  I had brought a small box containing a 
miniature pilot lamp as a fuse to protect the front end of the mult radio, 
so we tried this without the bandpass filters.  The bulb promptly blew.

Later we tried listening on the mult radio without any filters and 
discovered that the IC-765's front end was stronger than the lamp 
fuse!  While running on the tribander, we could listen on other bands using 
the 40M dipole with no bandpass filters.  Intermod QRM was pretty wild in 
this configuration, so we only used it on occasion.

I offer this information simply to suggest that on occasion, in certain 
configurations, that it may be possible to run SO2R without elaborate 
filtering.  Certainly 3-4 foot spacing between antennas would be pretty 
much worst case.  However, we were only running 100W.  Also, its been my 
experience that the IC-765 front ends are pretty good.  Some radios like 
the TS-830S have a coil in the front end that burns up under high RF levels.

So, while your mileage may very, use these data points to assess your 
situation.

73,


Dave/K8CC


--
CQ-Contest on WWW: http://lists.contesting.com/_cq-contest/
Administrative requests: cq-contest-REQUEST at contesting.com