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Re: Windows 7 config

 

I have to agree with Chris on this.? Running raw discriminator audio directly into the modulator is going to cause problems.? You need "something" ahead of the modulator to control the maximum deviation.? This is one of the reasons I disagree with the idea of coming out of the discriminator, going directly into the modulator and setting the system for 5 kHz in and 5 kHz out.

Years ago when I was on the TASMA technical committee one of the most frustrating problems I regularly faced was with people who would do this.? In a lot of cases the squelch tail was measured going out to 20 or more kHz of deviation, while popcorn and noise from signals that were only partially quieting went out to almost the same.? They don't understand.? It's just bad practice.

Burt, K6OQK


On Tue, Nov 1, 2022 at 10:29 AM, Chris Boone wrote:
I strongly disagree Scott... That's a recipe for disaster. Feeding wide band unsquelched noise to a modulator will cause the transmitter to over deviate. Remember the squelch noise out of a discriminator is half the bandwidth of the IF filter which means you have audio at 7.5 khz + coming out of the receiver.. Anytime I run flat audio, I always put a clipper/limiter circuit in line to prevent over deviation, and also to limit the audio bandwidth to 3 kilohertz maximum. Under FCC part 97 rules we are required to make sure that we use good engineering practices. Running raw discriminator audio straight into a transmitter modulator without any processing violates that rule. I've done that in microwave systems but that's a special case and you have the bandwidth to do it. In the crowded VHF/UHF bands, it's totally ludicrous to do so
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Chris
WB5ITT?
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