[Elecraft] VCO Voltage Checks - 40m

[David Wilburn]

While troubleshooting the "original problem" below, I was making 
changes, powering it up, checking, powering down, making changes, and at 
one point I had the radio off but 12v still on and connected.  I decided 
to re-flow the connection at the junction of C68 where it connects to 
R17.  There was a small spark, I stopped, turned off power, and 
disconnected it.

On the next power up I had an Info message.  I did not hear any relays, 
I think it may have been info 080, but not sure.  I got the same message 
(what ever it was 080, 108, or 118) on the next power up. I cycled power 
again, and the relays kicked and I got the Elecraft display.  Now the 
voltage reading for ALL bands is 7.94.  It seems the instant grounding 
of the input of Q18 (with my ***verified*** grounded soldering iron) is 
not desirable.  And just to make it interesting, when ever I figure out 
what gave way to the instant grounding, and get the part(s) in on-site, 
and re-installed, I will likely have the "original problem" there 
waiting for me.

Seems to me I read somewhere that you shouldn't stay after it after 
getting tired, cause you will make bad decisions.  Seems to me, it was 
even mentioned in a discussion with NU4I (Ken Moorman) today on the 
phone.  Some people's kids, they just don't learn.

Original problem
=====================================================================
The voltage readings for 7000/7300 are 7.92.  It is not much above the 
window of 7.5, but they do not vary with frequency as the others do. 
All other voltages are well within tolerances.  Adjustments to L30, do 
not change the voltage on the 7k range of frequencies.

I have installed D19, and D20, and C71 is a 120pf cap.  They are part of 
the rework eliminators supplied items.

I have verified C71-C74, and D21-D26.

I have re-flowed all the solder connections associated with K13, K14, 
and K15, and most of the surrounding circuitry.

Band	Low Freq	Voltage		High Freq	Voltage
====	========	=======		=========	=======
80m	3500		2.308		4000		5.99
40m	7000		7.94		7300		7.94
30m	10000		3.120		10150		3.677
20m	14000		2.587		15000		4.27
17m	18000		3.333		18200		3.539
15m	21000		2.482		21450		3.656
12m	24800		4.22		25000		4.61
10m	28000		3.512		28800		4.39


-- 

David Wilburn
dave.wilburn at verizon.net
K4DGW