You might be able to avoid the cost of bandpass filters.
I have successfully used quarter wave stubs to reduce the cross-talk
on 20m and 40m in my station. My 40m rotatable dipole is about 6"
below my 4 el tribander. Without the stubs, I could not put high
power on either band without overloading the receiver on the other.
Stubs are cheap to experiment with. I had some laying around so
had nothing to lose by trying them out. One each for 20m and 40m
works great--but I have to remember to remove the 20m stub from the
tribander feed to use it on 15m or 10m.
By the way, I only had an overload problem with a full gallon.
I can do SO2R on those antennas at 100W without the stubs.
Wayne, W5XD
-----Original Message-----
From: owner-writelog@contesting.com
[mailto:owner-writelog@contesting.com]On Behalf Of Barry Kutner
Sent: Sunday, December 03, 2000 16:51
To: Marty Tippin; writelog@contesting.com
Subject: [WriteLog] Re: SO2R Questions
***stuff deleted
> RF being conducted down the feedline. Similar results on the loop and/or
> dipole when transmitting on the vertical. As long as I'm careful to keep
> the two rigs off of the same band, do I need to worry about this? I can't
> afford to blow up a rig, and I can't afford (yet) to buy bandpass filters.
>
When I first ventured into SO2R I tried a vertical for radio 2. It
sucked, big time!
I would never try SO2R without stubs or bandpass filters (or both).
If you look at the math, for worst case - The separation due to
polarization difference is about 15-20 db. Running 100 W, that's 1
W at the radio. 1W at 50 ohms is about 7 volts at the rig's SO-239.
I think that's too much. Bandpass filters!
****stuff deleted
--
Barry Kutner, W2UP Internet: w2up@mindspring.com
Newtown, PA FRC alternate: barry@w2up.wells.com
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