System Saber Off Frequency

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Motradio
Posts: 176
Joined: Tue Jan 06, 2004 9:11 pm
What radios do you own?: HT1000, MTS2000, Maxtrac

System Saber Off Frequency

Post by Motradio »

Hi all,

I have a pair of System Saber UHF type III that has the 440mhz -470mhz split.

One programs up nicely on the ham bands, the other programs up but seems to be off freq (TX) by about 25khz across any freq 440mhz to 464.5mhz (checked on a freq counter). The Oscillator warp does not seem to make much difference to correct the problem (Not sure how much the warp can actually move a radio). Does this sound like anything anyone has encountered with the Sys Sabers?

I have the orig code plug that I put back into the radio and that was off freq, I created a NEW plug and it's off freq, dumped the other radios plug, and it's off freq. I have no idea what to look for, any suggestions :)

Could versions of the programming software cause issues like this?

Sandy
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kc7gr
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What radios do you own?: Motorola, Icom, Sunair (HF).

Re: System Saber Off Frequency

Post by kc7gr »

Motradio wrote:Hi all,

I have a pair of System Saber UHF type III that has the 440mhz -470mhz split.

One programs up nicely on the ham bands, the other programs up but seems to be off freq (TX) by about 25khz across any freq 440mhz to 464.5mhz (checked on a freq counter). The Oscillator warp does not seem to make much difference to correct the problem (Not sure how much the warp can actually move a radio). Does this sound like anything anyone has encountered with the Sys Sabers?
<snippety>

Based on the fact that the original codeplug was also off-frequency (most likely by the same amount), your culprit is probably a bad reference oscillator module.

I had the exact same failure in a Spectra not too long ago. Everything was off-frequency by about 50kHz, but I never got any sort of out-of-lock or similar error from the radio itself. I swapped the RefOsc, realigned, and the problem disappeared.

Happy tweaking.
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Bruce Lane, KC7GR
"Raf tras spintern. Raf tras spoit."
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AEC
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Post by AEC »

One other problem you may have overlooked is a defective Reference oscillator.

Since the reference oscillator 'sets' the radio's base frequency if you will, any offset from your transmit and receive frequency will be greater than the amount the reference oscillator may be 'off' by, so your 16.8000 Mhz. ref. osc. may be off by as little as 16.800134, or 16.798976...that sort of minute offset.

Remember the doublers in the radio......Multipliers and dividers Etc...

Just something to look into..


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DJP126
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Post by DJP126 »

I would also suspect the reference oscillator, followed by the 5V supply to the oscillator & then the VCO itself.
Dave
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Motradio
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Post by Motradio »

Thanks, I'm going to open up the working version and swap some modules. I'll have to figure out what is what not being Saber Saavy. The other option that I thought of was to program the radio 18khz off :-) Boy what a PITA that would be!

Anywhere on the web or batlabs with module photos. Is the ref-osc in the upper left hand side that looks like a typical buffered rectangular can type of oscillator?

Thanks for the help so far. I'll hold off on the Astro questions until I sort this one out :-)

Sandy
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DJP126
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Post by DJP126 »

The other option that I thought of was to program the radio 18khz off
The software won't let you do that.
Is the ref-osc in the upper left hand side that looks like a typical buffered rectangular can type of oscillator?
That's it.
Dave
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Motradio
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What radios do you own?: HT1000, MTS2000, Maxtrac

Post by Motradio »

Duhh, I forgot the synth step probabally is 12.5Khz :-)

Thanks for the tip on which module is the osc. I'll have a look tonight!

Sandy
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Motradio
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Post by Motradio »

Swapped out the Ref Osc from the off freq radio to the one that is ok, sure enough it now is off freq. So the KXN1135AA oscillator is the problem. Oh well, at least now I know which part to get :-)

Thanks again to all for the amazing pinpont help in solving the problem!

Sandy
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