Re: {Collins} R388 Readings



Philip ..

Unless I misunderstand your readings, the end point spread appears to me to be a lot out.  Looks like a total of 8 kHz end to end.  It really should be fixed.  PITA, but worth the effort.  You will likely have to remove a turn from the adjuster coil.

The deviations you show band to band don't make sense.  For example, bands 11 and 12 use the same crystal (14 MHz).   They should be out the same amount.  Bands 2 and 3, which use no crystal, should both be dead on -- at least showing the same difference from the center mark on the faceplate.  If you're using the BFO  and calibrator to hunt for zero beat, then the BFO is not set to 500 kHz.  

So, set the BFO as described in an earlier email using band 2.   Find the real "0" center mark on the faceplate using bands 2 and 3.  Then, either check each band relative to that mark, or go ahead and loosen and reset the dial so it lines up correctly at the center.  THEN check all of the other bands relative to whichever mark you want to use.  The crystals that need to be replaced will be obvious from the pattern.

How do I know this?  I'm ordering 10,666.67 kHz, 13.0 MHz, and 14 MHz crystals from ICM for my 51J4 on Monday.  Fortunately, my PTO is only off 1KHz end to end -- and that's good enough for now :)



> 
> 
>> OK
>> 
>> Here are the readings for the VFO on the 2 MHz band, MHz and amount off in KHz
>> 
>> 1.5/+3.5
>> 1.6/ .... 
>> 2.5/-4.5
>> 
>> Not that far out, it seems. I've seen much worse.
>> 
>> Here are the deviations, center of each band, and MHz, and error in KHz
>> 
>> 1/+3.5
>> 2/0
>> 3/+3.5
>> 4/0
>> 5/+4.5
>> 6/+1.5
>> 7/+3.5
>> 8/0
>> 9/+4
>> 10/+0.5
>> 11/+4.5
>> 12/+1
>> 13/+6
>> 14/+3
>> 15/+3.5
>> 16/0
>> 17/+3.5
>> 18/0
>> 19/+3.5
>> 20/+2
>> 21/+4
>> 22/+1
>> 23/+3
>> 24/0
>> 25/+5
>> 26/+2
>> 27/+3.5
>> 28/0
>> 29/+3.5
>> 30/+3
>> 
>> Most common deviation is +3.5. It would seem the easiest "fix" would be to slide the KHz dial on the shaft -2 KHz and leave as is.  What say you? Thanks.
>> Philip KA4KOE
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