[Fwd: Re: [Fwd: Re: [1000mp] Carrier on 50.110 +/-]]

[Garry Shapiro]

Remember this 25 MHz clock thread from before Thanksgiving? I ran the 
question in front of Bryon Campbell, WA4GEG, my Yaesu repair tech, and 
this is his response.

Garry, NI6T


Hi Gary,

On Monday 24 November 2008 10:53:06 pm Garry Shapiro wrote:
> Hi Byron:
>
> I don't know if you monitor the MP reflector regularly, but this
> guy has a problem with the 2nd harmonic of a 25 MHz oscillator
> giving him fits on 6m (and the fundamental on 12) as it drifts. Can
> you provide some inside info on what he might do?

Nope, sure don't. Staying booked up with radio repair work many weeks 
in advance leaves me little time to do anything except keep my nose 
pressed to the electronics repair grind stone. 

Those clock oscillators do creep around. He may consider replacing the 
drifting 25 MHz ceramic resonator with a high quality crystal. That 
would keep the clock nailed to 25 MHz (50 MHz for the 2nd harmonic.)

HTH,
Byron - WA4GEG

> -------- Original Message --------
> Subject: 	Re: [1000mp] Carrier on 50.110 +/-
> Date: 	Tue, 25 Nov 2008 08:10:42 +1100
> From: 	Tech <sg4 at aapt.net.au>
> Reply-To: 	All about Yaesu 1000mp <1000mp at mailman.qth.net>
> To: 	All about Yaesu 1000mp <1000mp at mailman.qth.net>
> References: 	<EA47A928A0E443849DE7FEC9762465B1 at acer>
>
>
>
> I have just been alerted to  the clock birdie, on 25.055 and
> drifting up as it got warmer up to 25.070.  This is, of course, not
> a problem on the fundamental, but the second harmonic (50.110 thru
> 50.140) is a TREMENDOUS problem when on was trying to use any 6
> meter equipment with the thing turned on.
> People have sent rigs back to Yaesu and they found
> resonators in their inventory that makes it come out around 25.014,
> cold, which is much less of a problem on 6 meters.
>
> The signal comes from a microprocessor clock @ nominally 25 MHz. 
> The real cure would be to use a real quartz AT-cut crystal at
> 24.995 in this circuit, but Yaesu cheaped out and used a
> surface-mount ceramic resonator instead.
>
> Does anyone know the circuit board and specific location of the
> resonator PLEASE.
>
> As these radios come in second hand there will be issues for owners
> like me who bought in good faith only to find an S9 signal on 12M
> and 6m drifting thru the band.
> Any assistance would be appreciated.
>
>
>
>
>
>
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