M1225 VHF off freq...

[n_zero_ndp]

Trying to get an M1225 VHF back on freq that started out
about -4.9 khz and the WARP OSC ADJ only gets it back to about -2.7 khz.
Anyone have any ideas I can try here???

No manual on-hand here of course......

[Lake Effect]

It sounds like you have a bad 16.8 mhz reference crystal. Part number 4880114R02. /\/\ won't sell it to you because it's "not field repairable". I guess we don't have the capability to unsolder and replace a crystal and readjust it's frequency. International Crystal will sell it and they know it by that number.

L.E.

[n_zero_ndp]

Thanks for the quick reply and the part number!!!

[AEC]

Not only can the reference oscillator cause that problem, but if it's on receive, the 1st IF can be off frequency, as well as the 2nd IF/Lo frequency, which will cause the audio to sound distorted and raspy, and force you to inject a stronger signal into the radio to open the squelch.

If this is occurring on TX, I would check to see what the frequency error is on receive as well...that 16.8 Mhz reference also controls the receiver and not just the transmitter.

=/- a few Hz. is not bad...but when it's over 10 Hz, then I would adjust the reference to within a Hertz or two.

Remember, if the radio transmits off channel, even by a few hundred Hertz, it can be enough to cause co-channel interference to other users on nearby frequencies....and garner you a warning/fine by the FCC for being out of band/tolerance with your radio.

[jackhackett]

The reason Moto won't sell the crystals is that when you replace one the radio's temperature compensation needs to be recalibrated, which they say needs to be done at the factory. You can get a crystal from another source, and it will probably fix the radio, but it most likely won't meet the rated specs anymore.

As far as adjusting within a few hertz, I think that's bit optimistic... the radio's rated accuracy is +/- 2.5ppm, which at 450MHz is what, 1125Hz? I'm not sure my R-2670 is even accurate to 1Hz. The frequency warp adjusment on a 1225 has limited resolution anyway, just set it as close as you can get.

[Bat2way]

=/- a few Hz. is not bad...but when it's over 10 Hz, then I would adjust the reference to within a Hertz or two.
Remember, if the radio transmits off channel, even by a few hundred Hertz, it can be enough to cause co-channel interference to other users on nearby frequencies....and garner you a warning/fine by the FCC for being out of band/tolerance with your radio.

This is just flat wrong. If true, no radio would even meet it's own tolerance specs.....

[n_zero_ndp]

Thanks for everyone's help on this one... It was the 16.8 mhz reference crystal.
Warp Oscillator adjustment is back to mid-setting again

[AEC]

=/- a few Hz. is not bad...but when it's over 10 Hz, then I would adjust the reference to within a Hertz or two.
Remember, if the radio transmits off channel, even by a few hundred Hertz, it can be enough to cause co-channel interference to other users on nearby frequencies....and garner you a warning/fine by the FCC for being out of band/tolerance with your radio.

This is just flat wrong. If true, no radio would even meet it's own tolerance specs.....

Flat wrong huh?

Gee, we just had a customer that was fined a nice chunk of change for being out of band by 112 Hz!

They are getting snotty, and if your radios can't stay in tolerance, many site owners will not even allow your radios in their buildings.

You can get stability to within several Hertz, I perform these adjustments daily on county radios as well as mining company equipment.

I have been able to get CDM1550s to within 20 Hertz on the bench, and I have 60 of them to program and align for a contract.

Sure, the Ref. Osc. readjusts on a continual basis, that's its job.....it has to track the VCO and the 2nd local oscillator.

If your reference signal is too far off, you can't get the VCO to track and an unlock condition will result.

Even if you do get the VCO to track, you can still create unwanted harmonics and third order intermod products that DO fall outside your license classification and it can and will bring problems to your door.