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Old August 24th 03, 03:52 PM
Doug Smith W9WI
 
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Chris wrote:
This is my first visit to this newsgroup...I am a new MI3.

I would like to put together a very simple QRP CW transceiver. The schematic
I am using includes a 3.560MHz crystal oscillator.

Maplin's, Farnell etc. sell 3.579545MHz or 3.686400MHZ crystal oscillators
respectively and I am wodering will these do the job or should I be looking
for a 3.560MHz crstal? The circuit does have a 65pF trimmer capacitor for
tuning but I want to sure about the crystal before I order.


(without seeing the schematic I can't know for sure but...)

I doubt the trimmer capacitor will be able to "warp" the frequency from
3.579545 to 3.560. I would be *certain* you won't be able to warp it
from 3.6864 to 3.560. I would expect more like maybe at most 5KHz
(3.579545=3.574).

I wouldn't think that would be a big problem though, with regard to
3.579. You'll just be operating on 3.579 instead of 3.560. (you do
need to double-check and make sure your license allows operation on the
higher frequency but I'd be VERY surprised if it doesn't.)

3.686400 will work from a technical standpoint too. However, I think
that frequency is in the phone band in Europe so it might not be a
suitable choice for a CW transceiver.
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com