Re: Frequency adjustment on a simple cw transmitter


James Compton
 

Chuck,
Thanks!  That's exactly the information I needed.  I ordered some of the polivaricon capacitor kits from Rex Harper at qrpme.com about a month ago, but he's been busy assembling kits for the Rockmite II and fighting snow on his farm near Limerick, ME so has been a little slow filling orders.  
I was certain someone in 4SQRP would know the answer to this question, since your net is on 7122 and getting the frequency nailed with homebrew rigs and purchased kits has to take some tweaking.
Thanks, again and Merry Christmas!
Jim Compton, K4JDC

-----Original Message-----
From: Chuck Carpenter
Sent: Dec 23, 2013 4:26 PM
To: 4sqrp@..., jdcompton@...
Subject: Re: [4sqrp] Frequency adjustment on a simple cw transmitter

Jim,

The lower frequency is typical of the Rock-mights too.

In most circuits with parallel resonant crystals, a series
capacitor/trimmer will raise the frequency. An inductor in series
will lower the frequency.

Series resonant crystals such as the 7114s from ESS will be higher
than the marked frequecy.

A combination of trimmer and inductor in series can be arranged to
both raise and lower the frqeuency.

There are examples of such circuits in the W1FB's QRP Notebooks and in EMRFD.


Chuck Carpenter, W5USJ
EM22cv, Rains Co. TX

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