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GM300 reads low in transmit frequency

Posted: Mon Oct 12, 2009 1:00 pm
by K7KTR
I am sure there is a post to this somewhere, but I have not been able to find it.

I have a UHF GM300 and the radio works great, I will be using the radio as a 15 channel steerable remote base with my S-Com 7330 Controller. The Controller switches channels fine, But I would like the transmitter to be closer then what is displayed low on the frequency counter about 300-600 cycles low. Out of the 15 channels programmed into it and they all read low.

Is there a way to bring up the transmit to be closer to what I have programmed in there?

Any help would be greatly appreciated.

Keith
K7KTR
[email protected]

Re: GM300 reads low in transmit frequency

Posted: Mon Oct 12, 2009 1:39 pm
by Batwings21
You would use the gm300 rss's tuner menu to adjust the reference oscillator soft pot.

Re: GM300 reads low in transmit frequency

Posted: Mon Oct 12, 2009 3:17 pm
by K7KTR
Thank You for posting that, I will try that out.

73 OM
Keith
K7KTR

Re: GM300 reads low in transmit frequency

Posted: Mon Oct 12, 2009 3:54 pm
by Satelite
Hello:
Before you use the rss to retune:
Disasseble and clean the 16 pin conections between the rf bd and logi bd.
This is normally the culprit that causes low freqs ect.
Satelite

Re: GM300 reads low in transmit frequency

Posted: Tue Oct 13, 2009 8:48 pm
by Bigred
If you;re lazy, you could twist the coil for the reference oscillator.

OW! That hurt. What did you do that for?

Re: GM300 reads low in transmit frequency

Posted: Wed Oct 14, 2009 5:42 am
by Bill_G
All oscillators slow down, and 300 to 600 hz low is normal. Definitely disassemble and clean the board interconnect pins as suggested earlier. Known problem in the model. And then adjust the freq in the service menu. But, you will gain nothing in real world performance. In radios that accept +/-5khz deviation, 600hz low will pass through the IF without notice. It's always good to be right on the money though.

Re: GM300 reads low in transmit frequency

Posted: Wed Oct 14, 2009 10:34 am
by jackhackett
You should NOT adjust the frequency by adjusting the oscillator coil. Doing so will throw off the temperature compensation.

300-600hz is probably just normal drift, the feedthru connector will usually make them go off freq by 1Khz or more with approx. 2Khz being common.

And as I've said before, if you have the older style feedthru connector cleaning it won't be enough, they physically break.

http://batboard.batlabs.com/viewtopic.p ... ru#p302285