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Re: VHF MTR2000 Poor Receive Performance


 

Not going to lie, I haven't been able to figure out the Rigol enough to show the generator amplitude down past the -100dbm level so it really could be off. I need to figure out how to view it that low.

I mean, my test results showed the MTR at the receive port at 0.4uV (-115dBm) and 0.5uV (-113dBm) after the duplexer. I know the duplexer has 1.67dB of loss and then my jumper cables tested about 0.15dB loss so that explains the 2db difference. Even if the levels are off from the service monitor, it still shows at least the 2db loss that I've calculated using the spectrum analyzer.

Didn't think of checking site noise floor, I'm running this at home before it ships off to the site. I do know I have VHF noise birdies from PoE cameras at my house. I was talking to the local repeater/rf guru about this and he asked my about my antenna setup I was using.

I live in an HOA and can't have external antennas but I managed to slip a dual band magmount up on top of our disused metal chimney cap. I never had an issue with running UHF repeaters on that setup as there's probably enough metal up there for UHF. However, he said there's probably not enough metal/groundplane for VHF, which was a theory I thought of early on but discounted as it works great for VHF simplex but this is duplexer we're talking about.

The repeater is on its way to the dealer, I can run a site desense test after I get it back or maybe grab another VHF radio and use it for testing.

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