[OKDXA] Reference oscillators

[Kim Elmore]

This is exactly the same method I use for my TS-930S TCXO. The only rub is 
that the '930 TCXO is very hard to access, so it's not something I do very 
often.  I can estimate how far off my calibration is by using the USB vs 
LSB approach by simply tuning the dial until the tones I hear in each 
sideband are identical. The '930 only tunes in 10 Hz increments, so I can't 
estimate the error to anything better than 10 Hz this way, though if I used 
a counter on the audio, I could probably get the error to any arbitrary 
accuracy.

I don't know how I'll do this if I ever have the wherewithal to get a 
Ten-Tec Orion :)

Kim -- N5OP

At 09:46 PM 4/8/2004 -0500, you wrote:

>In the case of an Icom 756 (original version and possibly the subsequent
>variations) the radio relies on one master oscillator for just about
>everything including the internal marker generator. If that oscillator is on
>the money, everything else pretty much falls into place.
>
>Here's how I check mine:
>
>Let the rig idle for 30 minutes or better, then set the dial to 10.000 Mhz
>and the mode to AM. Pick a time when WWV at 10 MHz is coming in fairly well
>(not much QSB) and you hear the 400 Hz background tone between clock ticks.
>Turn on the internal marker generator. You'll probably hear a low tone near
>zero-beat. Adjust the oscillator through the hole in the lower right side
>panel (near the front) until the zero-beat goes sub-audible. Set the AGC to
>fast or mid level response and watch the S-Meter 'wobble'. If you have a
>steady hand, you can tweak the trimmer cap until the S-Meter holds almost
>steady. At that point you are within a fraction of a Hz relative to WWV.
>
>As a secondary check of the alignment, turn off the internal marker
>generator and flip between LSB and USB. The pitch of the background tone
>from WWV should be the same.
>
>I haven't tried this at 5 or 15 MHz, but I suspect it will work. This is a
>variation of the old freq counter tweak for counters that use a 10 Mhz
>clock... Plug in a few feet of wire as an RX antenna on any AM SW receiver,
>tune WWV at 10 MHz, lay the wire over the freq counter case until you hear
>the two signals beat against each other, then adjust the frequency counter
>oscillator for zero-beat.
>
>- AC5UP
>
>
>
>
>
>
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                           Kim Elmore, Ph.D.
                        University of Oklahoma
         Cooperative Institute for Mesoscale Meteorological Studies
"All of weather is divided into three parts: Yes, No, and Maybe. The
greatest of these is Maybe" The original Latin appears to be garbled.