> I am moving a 463/468 MHz Micor repeater to 444/449 MHz. I
> ordered new
> xtals from ICM and the receive xtal is OK. However I can't
> get the xmit
> xtal to pull onto freq. It will pull within 3 KHz above 444.350 MHz.
I'm assuming this is a real Micor repeater, not a converted mobile, so you
should have a KXN1052 transmit channel element. Open it up again, and ;ook
behind the trimmer cap. You should see a ceramic disc cap that is not quite
parallel with the back of the trimmer cap - that's your target. Further
behind the ceramic disc is a plastic-case transistor (just to verify we're
on the same page). Look at the value of the ceramic disc; it should be
somewhere in the tens of pF range. Increase its value by approximately 20%
and you should be in the ballpark for moving from 463 to 444 (i.e. if it was
22 pF originally, use 27 pF instead). Lacking any other means of real
compensation, use an NP0 cap.
As others have pointed out, this doesn't give you any form of accurate
temperature compensation. This only lets you center range of the trimmer
cap so you can put the transmitter on frequency. If the repeater will be in
a temperature-stable environment (say, +/- 10 or 15 degrees ambient as a
ballpark), you might be OK. Next time, spend the money and send the element
to ICM and let them do it right.
--- Jeff
--------------------------------------------
Jeff DePolo WN3A - [EMAIL PROTECTED]
Broadcast and Communications Consultant
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