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SP50 UHF frequency problem
Posted: Fri May 26, 2006 5:44 am
by arlojanis
I have a UHF SP50 that appears to not transmitt or receive. But it does transmitt in the wrong place. When I PTT the red light flickers several times and then stays on. Transmitt frequency runs all over the place. Sometimes it is 6.99 mHz high in frequency and moves around. What's the problem?
Posted: Fri May 26, 2006 8:41 am
by Lake Effect
Possibly the reference oscillator crystal. Usually the radio will just be dead if the crystal is bad but I ran into one about a month ago that did about the same thing as yours.
L.E.
Posted: Fri May 26, 2006 6:00 pm
by AEC
I am thinking the very same thing....A defective reference oscillator.
As long as there is an active signal being seen by the micro, the radio will attempt to lock onto whatever frequency the reference oscillator is 'tuning' to, which is 'wandering', and this will cause the radio to wander as well, every time the oscillator 'self-warps' the radio will continue to lock to the new frequency, and since this changes with voltage and time, the radio's actual operating frequency will also change or warp as well, until the reference oscillator finally dies and the radio stops operating.
Posted: Sat May 27, 2006 6:32 am
by arlojanis
16.8 mHz oscillator is stable. I noticed when transmitter does lock on frequency, the mic mod is high and the PL mod is low. I have found that it will transmitt on frequency when supply voltage is lowered to 5.5 volts, but no receive. Mod is normal. After transmitt there are three beeps in speaker when using any supply voltage.