SPECTRA Transmit Problems

[Allan Amster]

I have a 45 Watt trunk mount Spectra. The radio receives fine. I went to transmit and found I had no transmit. Checking further I found that we only had 24 watts for output. Checking the frequency with a counter I found that the freq. is showing 416 Mhz and NOT stable, as it continues to random!

Any ideas?

Allan

[jmr061]

What model is it?

Jason

[Rick Rock]

Make sure you have power to the main wire on the 2 pin plug for the radio.

[kc7gr]

First thing to do is eliminate the vehicle environment as the source of the trouble. Stick the radio on the bench under controlled conditions, and hooked up to a service monitor. If it performs well on said bench, then have a good hard look at the primary power leads for the radio in the vehicle (both A+ AND ground -- you may have a bad ground).

<Reference to RefOsc removed by Yours Truly>

UPDATE 15-Jan-06

Having re-read the thread, I retract my idea about the reference oscillator. I'm thinking this may be a VCO issue (leaky caps, maybe?). The VCO does, after all, output directly to the PA.

Happy tweaking.

[jackhackett]

Well I'd agree with Bruce about bench checking it, if you've got the facilities to do that it can't hurt.

The statement in the first post that the radio receives fine would tend to rule out the ref. osc. though.

Seeing low power and random freq. readings (I'm guessing they used a hand-held freq counter?) could indicate that the PA is spurious, which could be caused by a number of things, among them that cap in there leaking all over the board...

[AR15Ron]

I have a 45 Watt trunk mount Spectra. The radio receives fine. I went to transmit and found I had no transmit. Checking further I found that we only had 24 watts for output. Checking the frequency with a counter I found that the freq. is showing 416 Mhz and NOT stable, as it continues to random!

Any ideas?

Allan

Too little info I think. As someone else suggested, put it on the bench in a controlled environment and see what it does. Also, I have bought spectras off ebay and found them both off frequency and with the power output turned way down. You can fix that easily enough in the alignment section. I wouldnt recomend doing that sort of thing without a service montiro, unless it is for HAM use. Close enough is close enough for me, but probably not for public safety use. Also, unless you are 100% certain of your frequency counter, many of them cannot be trusted. If it is battery operated it could be getting funky as the batteries get weak. I have one that get progressively sketchy.

Ron