UHF Maxtrac deviation issues

[KG6MDW]

I have been using a 449-470 as a control receiver on 445mhz successfully for a year; but I now have to move it down to 439. I have re-programmed the radio and re-tuned the front end and receiver. It was having issues controlling power so I put in a pot into the base of Q455 to limit the power. But now it doesn't seem to limiting the deviation; the RSS doesn't seem to change anything. I thought it was where I was injecting the audio; but It even does it with the microphone.

I have located the 900mhz page where the deviation control was bypassed; Is this the only way I can fix it?

Thanks

Trevor

[Jim202]

Like most other Motorola software controlled radios, the Maxtrac has soft pot tuning values to control the power and
deviation of the radio. If you take it out of the normal radio range in frequency, these problems show up real fast.

One thing you might want to try is to do a retune and calibration on the radio. People have been known to just
blow new codeplugs into radios without the knowledge of where any of the soft pot tune values were or are now.
As the issue is at hand, you now have issues.

Jim

I have been using a 449-470 as a control receiver on 445mhz successfully for a year; but I now have to move it down to 439. I have re-programmed the radio and re-tuned the front end and receiver. It was having issues controlling power so I put in a pot into the base of Q455 to limit the power. But now it doesn't seem to limiting the deviation; the RSS doesn't seem to change anything. I thought it was where I was injecting the audio; but It even does it with the microphone.

I have located the 900mhz page where the deviation control was bypassed; Is this the only way I can fix it?

Thanks

Trevor

[KG6MDW]

Like most other Motorola software controlled radios, the Maxtrac has soft pot tuning values to control the power and
deviation of the radio. If you take it out of the normal radio range in frequency, these problems show up real fast.

One thing you might want to try is to do a retune and calibration on the radio. People have been known to just
blow new codeplugs into radios without the knowledge of where any of the soft pot tune values were or are now.
As the issue is at hand, you now have issues.

Jim

I did re-calibrate the radio; that is what is confusing me; i've watched the steering line and it stays at 9.6v even with it turned all the way down. I guess I'm a little too far out of band for it to compensate.

Thanks.
Trevor

[rocketman]

the receive VCO can be adjusted to bring the SL voltage more in line.