Distorted transmit audio FLEX-1500 with WSPR

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  • Updated 2 years ago
I have been using my FLEX-1500 on WSPR occasionally. I am using Dell desktop recently updated from 8.1 Window 10 with VAC 4.13 for audio. Since I am switching between the FLEX and my K-3 for various modes,I usually have to recheck all my settings for audio sources, CAT and PTT. I sometimes find that my transmit audio as heard through the monitor speaker sounds very distorted on transmit. The panadapter screen also shows a transmit signal that isn't normal. Since my signal is not properly modulated, I shut down transmit and just monitor. I try to keep my input audio levels low and reduce the transmit gain for 0db or less.

What can be causing this problem and what should I check?
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Phil N3ZP

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Posted 2 years ago

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John M

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Hello there Phil.

When your Flex-1500 goes into transmit, can I assume your mode is set for "DIGU"?  If that is the case; as it should be; then  click on your "TUNE" button to activate your transmitter and look at your TXMT Meter which should have ALC mode selected.  Make sure that the ALC level is at 0bd or slightly less.  If it is not in that zone, then use the VAC1 TXGain slider near the bottom center of your power sdr control panel and adjust it so that the ALC meter reads no more than 0db; otherwise your transmitted tone in WSPR will be distorted. 

I hope that helps you out in some way. 

Regards:  John  VE3INH
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Phil N3ZP

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Hello John,

Thanks for the comment. My ALC setting was 0db or less, so I knew that wasn't the problem. I always watch the panadapter display on transmit and try to keep it looking clean and in the passband. I changed the PTT setting from CAT to a separate comport and that seems to have corrected the problem. It may have been switching in and out of transmit at a high rate.

Thanks.

Phil N3ZP
(Edited)
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John M

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Hello there again Phil.

That is very interesting.  I had never experienced that before. I also keep a close eye on the panadapter display when I am transmitting to ensure a clean signal is going out.  If the same situation occurs, your experience certainly will give me a secondary option to explore in terms of resolving the problem.  Thank you for pointing that out.

Regards:  John  (VE3INH)