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Old 20-Jun-2017, 4:53 PM   #48
JoeAZ
Senior Member
 
Join Date: Mar 2017
Posts: 413
Quote:
Originally Posted by jrgagne99 View Post
In my latest experiment, I combined a Stellar Labs 30-2476 VHF yagi with a DB8e 8-bay using a UVSJ combiner (Stellar labs 33-2230 UVSJ). Real channel 25 (WNNE) is strong enough that it is separately received by both antennas, even though I point them 90-degrees off from the Real-25 tower to pick up Burlington stations. I confirmed this by separately removing UHF and VHF feeds to the UVSJ, and I receive Real-25 in both cases. Strangely, when both feeds to the UVSJ are populated, the UVSJ does not allow Real-25 to pass through to the output.

Any thoughts on what might be going on here? Is this some form of destructive interference where some very low amplitude CH-25 signal passes through the VHF-pass filter and destructively interferes with the CH-25 coming through the UHF-pass section?

Is this an example of UVSJ's "not always doing what they're supposed to" and why I've seen several people on this forum recommend using separate coax runs and an A/B switch for UHF and VHF instead of using a UVSJ combiner?
Thank You for so eloquently describing what I have experienced in
the field so many, many times.... In theory, a good UVSJ should
work under all conditions but in practice, that is not so. That is why
I always recommend keeping separate coax runs and using an A/B
switch.....
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