GTX PL LEVEL

This forum is for the discussions targeted at converting various models of Motorola equipment to operate in the 900MHz Amateur Band.

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kj6ko
Posts: 36
Joined: Sun Oct 30, 2005 7:47 pm

GTX PL LEVEL

Post by kj6ko »

Is there any way to adjust the PL TX level? About 1.1KHz in this 900 GTX. Too much?? OK at that level??

Thanks
AEC
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Joined: Wed Dec 22, 2004 7:56 pm

Re: GTX PL LEVEL

Post by AEC »

With the 900 band, the deviation is narrower...2.5 Khz, so you will have to tailor the PL deviation to match....about 500 Hz. or the tone will be too strong.

A 3 Khz PL deviation is far too wide for acceptable use on 900.

Even on a +/- 5 Khz FM radio with 10 Khz total deviation, the PL deviation is kept at no more than 750 Hz, as this is all the radio requires to properly decode and then strip off the tone before it is sent to the audio circuits so you don't hear the hum, unlike the N.Mexico, Taos 'hum' that's been rumroed to exist....you don't want that in your ears all the time now, do you?
kj6ko
Posts: 36
Joined: Sun Oct 30, 2005 7:47 pm

Re: GTX PL LEVEL

Post by kj6ko »

Great!....but how is it adjusted? Did I miss a page in the RSS? I can't find PL deviation adjustment. If I set max dev @ 2.6KHz, PL is at about 800Hz. The PL level seems to move with the max dev adjust in the RSS, but no separate adjustment?

Thanks.....Greg
AEC
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Posts: 1889
Joined: Wed Dec 22, 2004 7:56 pm

Re: GTX PL LEVEL

Post by AEC »

You might want to try adjusting the VCO modulation as this will set the TX audio level as well...it's a trade-off with the GTX series.

That's the one BIG headache with softpots, and old RSS---They don't allow individual adjustments to fine tune the radios.
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