[TenTec] Alignments

Grant Youngman nq5t at attbi.com
Sat Jun 14 21:03:24 EDT 2003


> So,  where is the TCXO adjustment?  Maybe two possibilities:
> the "shiny" silvery gadget with a hole in the top \

The TCXO adjustment is the metal can with the adjustment screw 
visible through the hole on assembly A10.  Either the can or PC 
board next to it (I forget which) is screened with a 44.55 Mhz 
marking.  I used a small blade ceramic screwdriver.  There's not 
much "vernier" to the adjustment, so you need a little "touch" to get 
it right.

The MixW/DIgipan approach may be more precise ... but I suspect 
you'll get as close as it's worth getting with my quick and dirty 
method (beating the cal signal audibly against the SPOT tone in 
either LCW/UCW).  In any case, once stable, the TCXO wanders a 
couple of Hz or so around the adjustment point over time, so there's 
just so much pin-point precision that's worth the trouble.

Let the radio warm up for at least 4 hours with the bottom cover in 
place before you make the adjustment.  I took some long term 
measurements and found it took about that much time for the 
TCXO/radio in my shack's environment to reach thermal stability.

Grant/NQ5T

PS.  The last time I posted about measuring the warmup drift 
pattern, there was much gnashing of teeth (and interesting lectures 
on variable proagation delays, etc.) about how measuring against 
WWV would introduce all kinds of errors, etc. and was probably 
causing the pattern I was seeing.   I've since used the now 
ubiquitous z3801a, and found the same warmup drift pattern I found 
when using WWV.   FWIW ....



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