Jared;
You need to warp 4khz not 400hz... If they were made up for 146.01 I
would assume that they can do that. So now we need to look at why they
are not... 10v reg power supply needs to be 10v +/- .1-.2v . The temp
comp line to the EC needs to be driven to something by a 5ppm or eq
channel element installed in the board, not necessarily even to be in
band.. just to hold the comp line where it belongs... assuming it is not
a comp line dc issue or a 10v reg dc issue, it is possible the xtal is
from an exec II and while the xtal is the same freq, it is not the same
cut... it may or may not tune in a Mastr II. On the other hand Mastr II
xtals will in general function in both Exec II and Mastr II as a more
precise cut.
There is also a section of striplines at the top of the element that are
actually there to fine trim the freq of the oscillator in the element.
It is normally covered by the temp com circuit in an 2C and 5C.
sometimes you can either repair or cut parts of that stripline area to
move the center of the xtal.
I would suspect that if the xtal is the correct one and it was assembled
correctly.. it is more likely a DC issue to the comp line or 10v reg...
The comp line needs to sit about 4.5 v, as I recall, for proper
operation at room temp...Any 5C plugged in a spare element slot will
drag it to the correct voltage... you can also measure it with a volt
meter on any unused element pin spot that is not in use on that board...
While in a mobile the comp line is common to the TX and RX.. in a
station it is not.. you did not indicate what Mastr II you were working
with..
Doug
KD8B
KE4ZDG wrote:
>
> Hey folks,
>
> I'm working on a GE Mastr II high band repeater. Someone gave me some
> crystals that were made up for 146.010 RX. I installed one in an EC
> ICOM and the best I can adjust for is 146.0064, which sounds really
> scratchy when I inject a >3k deviation signal on 146.010. When I tune
> the monitor down to 146.0064, the RX audio cleans right up.
>
> I've backed out the screw until there's no more threads left in the
> ICOM. Is there a capacitor I can change or add to give me a little
> more tuning range to the ICOM? I just need the crystal to go up a hair
> more (400 Hz on the crystal freq).
>
> I know I'm promoting cheapness by not buying another crystal, but the
> club doesn't have much money to spend.
>
> Thanks,
>
> Jared
>
>
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