[CQ-Contest] SO2R - How Good is Good Enough?

Dick Green WC1M wc1m at msn.com
Wed Dec 7 16:25:44 EST 2005

Ideally, 1-2 KHz from the second harmonic. With certain frequency
combinations you might hear a tad of hash or some light clicks elsewhere in
the band, and they may get a little louder near the harmonic, but not enough
to prevent hearing weak stations. If you use proper stubs and high quality
bandpass filters you should get this kind of performance at 100W. 

At 1500W, it's hard to get that close with antennas mounted on the same
tower - especially tribanders. If you have monobanders, 20/15 and 40/10
should be OK. Other combinations can give you interference in both
directions. You might have to use multiple stubs to cure certain problems.
For example, originally I used an inverted vee on 80 that was in a tree very
close to a tower-mounted tribander and a 4-square. I had to add a stub to
null 80 on each of the other bands (I use a multiple stub switching system
like the design on K1TTT's site.)

The ultimate answer is physical separation. Some of my antennas are
separated by 200-300 hundred feet and don't require stubs or filters unless
they are pointed directly at each other.

73, Dick WC1M

> -----Original Message-----
> From: Pete Smith [mailto:n4zr at contesting.com] 
> Sent: Wednesday, December 07, 2005 11:34 AM
> To: cq-contest at contesting.com
> Subject: Re: [CQ-Contest] SO2R - How Good is Good Enough?
> Sorry, I think I should have mentioned my constraint that 
> makes the problem particularly interesting - 1 97-foot tower, 
> all antennas either on or supported by it (including a shunt 
> feed for 160)
> 73, Pete N4ZR
> At 02:13 AM 12/7/2005, Pete Smith wrote:
> >I've just spent a lot of effort, and probably too much 
> money, on antenna switching and filtering for SO2R.  The 
> resulting system seems to work quite well, at least at 100 
> watt power levels, but I realized I don't have a good sense 
> of what experienced SO2R ops and station builders consider to 
> be "good enough."  In particular, how close to the harmonics 
> of your transmitter frequency should you be able to listen 
> effectively with the second radio?
> >
> >73, Pete N4ZR
> >The World HF Contest Station Database
> >was updated on 23 October 2005
> >Over 3000 contest stations at
> >www.pvrc.org/WCSD/WCSDsearch.htm

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