[Elecraft] 4MHz calibration & frequency counter failure

Mon Nov 10 23:52:01 2003

Thanks for all the responses.  I think I checked everything except 
removing RP3.   Although the collectors of Q9, Q10 and U6 Pin 15 is 0.71 
(spec is 2.0 - variable) it seems to me to be close enough.  I guess I 
will spend tomorrow working on RP3 (although Elecraft recommended not 
removing it).

Happy Veterans Day.
WB7SBD.  de ed

>It sounds as if the PLL reference oscillator is NOT working.
>
--CORRECT AS PER APPENDIX E PAGE 9, RMS=0.91

>Start measuring voltages in the area of that oscillator.
>
>Another thing that can mess up the PLL reference oscillator is bad solder
>joints on the Thermistor board you installed instead of RP3.
>
>If the voltages listed for U6B are not correct, most likely the problem 
>
-- VOLTAGES ARE W/N RANGE

> see if D16 and 17 are installed correctly. It can also fail if C84 and 
> C85 are loaded with incorrect values in  the right holes. Also recheck 
> carefully the RP3 soldering 

--  D16 & D17 (RF board) are correct

>
>OK, so TP3 is good.  Which rf probe are you using, how is it hooked up?
>
--I'M USING THE RF PROBE PAGE PAGE 44  -I CAN PLUG IT INTO TP3 THEN 
CONNECT MY FREQUENCY COUNTER AND GET CORRECT READINGS (implying the 
Elecraft probe is OK)

>
>Well, the 4 MHz oscillator is working, or you'd never see CAL FCTR.
>Since you can't see 4000.00 (or 3999.96) at this stage, then the
>probe or the probe amp is broken.  Check over which pin is shield and
>which is signal on the probe.
>
--SHIELD CLOSEST TO ENCLOSURE SIDE "ACTIVE" SIDE TO INSIDE

>  Check all connections round about Q9 and
>Q10.  You might do signal tracing.  Plug the probe into TP3, and use
>your frequency counter at the collectors of Q9 and Q10 to see how far
>the signal is getting.
>
--THE COLLECTORS OF Q9, Q20 AND U6 PIN PIN 15 IS 0.71VDC (Elecraft spec 
2V but can vary)

-------- Original Message --------
Subject: 	4MHz calibration
Date: 	Sun, 09 Nov 2003 22:04:24 -0800
From: 	E.G. Bixby <[email protected]>
To: 	[email protected]

REF: K2, #03838, Alignment test part II.

When I plug in the frequency counter to P6 & TP3 then activate CAL FCTR 
I should get 12090kHz - my reading =0.0.  But my frequency counter reads 
OK both at TP3 and through the Elecraft rf probe.  Everything is w/n 
tolerances in the trouble shooting section (reference oscillator; VCO 
output and VCO buffer are all OK). 

The 4MHz oscillator on the control board  (left pin of C22) should read 
4K but reads 0.  C22 is all over the board on my frequency counter. 

Any idea what to try next?

Thanks in advance
WB7SBD de ed