MTR2000 simplex TX interfering with RX (TX idle frequency problem?)

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VA3HF
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MTR2000 simplex TX interfering with RX (TX idle frequency problem?)

Post by VA3HF »

Hello, I have a VHF MTR2000 problem I'm trying to see if it has been a problem elsewhere - recently found 2 stations causing this problem. The TX side of the MTR2000 is generating a carrier (when not transmitting) on the RX frequency when set to simplex even thought the TX idle is 50kHz off the TX frequency. I even set it further away and it is still interfering with the receiver. It is heard strongly outside the radio chassis with a portable. Haven't gone into troubleshooting it yet - the company usually just sends it away for repair but since I found 2 radios doing the same thing out of 4 sites, I thought it might be a common problem to others.

thanks
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wavetar
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Re: MTR2000 simplex TX interfering with RX (TX idle frequency problem?)

Post by wavetar »

Yes, set the idle to at least 1MHz away and your issue should be gone. I haven't seen it much, as 99% of the MTR2000 I deal with are repeaters, but I do recall needing to do that for a base station years ago.
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Bill_G
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Re: MTR2000 simplex TX interfering with RX (TX idle frequency problem?)

Post by Bill_G »

There is an automatic idle freq setting. It generally picks a good one that doesn't nail it's own rcvr.
VA3HF
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Re: MTR2000 simplex TX interfering with RX (TX idle frequency problem?)

Post by VA3HF »

The TX idle frequency was originally set to 50KHz below the simplex frequency when we noticed it was actually on the TX frequency which was also the RX frequency. We then changed the idle frequency to -300KHz below the simplex frequency and it still was on the RX frequency causing the receiver to unsquelch. This is the problem. The idle frequency isn't changing from the set TX frequency. We also tried to change the simplex frequency and the problem followed the frequency change.
Karl NVW
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Re: MTR2000 simplex TX interfering with RX (TX idle frequency problem?)

Post by Karl NVW »

You've got a failed switching control circuit; the exciter is still keyed on the transmit frequency even though the rest of the radio is in receive.
Karl - WA8NVW AFA5VB
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