VHF HT1250 - 1.3KHz off frequency - fault?

[g8tzl2004]

I have a mint condition VHF HT1250 which is 1.3KHz off frequency. The radio was made in Dec 2006..so its around 7 years old.

I've never seen a VHF Motorola this far off frequency...except a GM300 which had the dirty thru pin issue. I've seen UHF stuff around 1KHz off frequency but VHF stuff tends to be within 500Hz

Should I be concerned about the HT1250 being 1.3KHz off frequency?....or is it the ref osc crystal which has "aged" more than expected and just needs to be warped back onto freq?

[wa6ylb]

As with anything that has a reference osc, you have to put them back on freq after several years. They tend to stop drifting as much after 10 years or so.
Very common. Set it back on and enjoy. If it was say more than 5 Khz off, then be warry. Usually if there is a major issue, such as 5-10 Khz off freq, you may want to have it checked (like reference voltage within the unit, or replacement of Osc crystal or element).

B.

[CircleBat]

sometimes, when a radio gets dropped hard, it will drift off frequency.. Also a firmware upgrade will cause a warping error

[g8tzl2004]

Thanks for the info. I guess one aspect that concerned me was that the "equivalent" error at UHF would have been 3x greater..so if it had been a UHF radio and it was 3.9Khz off frequency (ie 1.3Khz x3) I might have been a bit warry.

[Will]

Reference Oscillator adjustment time. It is in the Tuner s/w.

[CircleBat]

I have seen chip caps breaking off that feeds the 16.8 mhz oscillator causing a warp error.. your gonna hafta shotgun the cause of the warping error.. there are moments where the frequency errors are so bad that it cannot be retuned with the software..

CircleBat

[escomm]

Retune the radio and be done with it. No big deal. 1.3KHz off is probably no good for a narrowband system

[g8tzl2004]

An adjustment of the Ref Osc Warp from 285 to 246 did the trick...its now within 100Hz

[AEC]

...its now within 100Hz

Even that error level is too much for my liking....That will lead to large excursions as you 'wander' up the frequency and can lead to errors several kHz. off channel.
I try to narrow the error to under 50 Hz. more stable and the wiggle room is greater as well.

Remember, the reference oscillator is the 'go to' frequency the radio uses to measure channel accuracy and stability.
Check splinter channels and regular channels at several points within your band usage, you may see many that are dead on, and others showing errors as high as 1-3 kHz. at the upper band edges.

[d119]

...its now within 100Hz

Even that error level is too much for my liking....That will lead to large excursions as you 'wander' up the frequency and can lead to errors several kHz. off channel.
I try to narrow the error to under 50 Hz. more stable and the wiggle room is greater as well.

Remember, the reference oscillator is the 'go to' frequency the radio uses to measure channel accuracy and stability.
Check splinter channels and regular channels at several points within your band usage, you may see many that are dead on, and others showing errors as high as 1-3 kHz. at the upper band edges.

I agree with AEC. These adjustments are even more critical for narrowband operation. 100Hz would be too much for my liking as well. I always try to get it as close to 0Hz as possible. If you end up going past 0Hz, you need to look at it from both sides (+ and -) to determine which side is closer to 0Hz.

While it doesn't apply to this particular radio, reference oscillator settings are even more critical at 800 and 900MHz than VHF/UHF.

[g8tzl2004]

The Test Frequency was at 173.825 MHz.

When I checked the frequency at 145 MHz, it was 60Hz out. If I had set the softpot to 245 vs 246 I think I would have been spot on...but 60Hz is close enough for me!!!

I have previously zero beated VHF and UHF signals using 6KHz filtering and USB and its interesting how many signals are off frequency by over 500Hz. I guess you get real issues when one station is + 1KHz and the other is -1KHz...so the overall error is 2KHz!!