[Elecraft] VCO Voltage Checks - 40m

[Don Wilhelm]

Dave,

I do not have enough data to tell you whare to start on the current problem.
Check voltages and look for charred components or burned PC board traces.
Be certain the 8 volt regulator on the control board is supplying voltage
and follow its path onto the RF Board.

On your 'original problem', you apparently have installed the "Rework
Eliminators" and I must offer yet another RANT:

You may not have fully followed the instructions that came with the 'Rework
Eliminators'.
My beef with the rework eliminator folks is that this one item is SO VERY
important and they apparently still do not put it in big bold warning
letters.

When you change C71 to 120 pf in the VCO area you must enter the secondary
menu and set D19 - y.

But also keep in mind that with the 120 pF value at C71, your VCO voltage
range can no longer be completely tested - the lowest voltage will now occur
on 60 meters at 5300 kHz, so you will have to remember to revisit the VCO
voltage alignment after the K60XV is installed.

The K2 manual is quite correct in saying that none of the K60XV parts should
be installed until after the K2 has been completed and aligned.
Unfortunately the K60XV part of the Rework Eliminators is NOT, I repeat NOT
'plug and play'.

About 6 months ago I had several email exchanges with Gary H. about this
problem, and at one point he said something would be done about it, but
still this matter crops up over and over again, so I can only assume that it
has not been corrected in their documentation with adequate warnings.

In other words Dave, the Rework Eliminators have broken your K2 by causing
you to try to correct a problem where there was none.

RANT off.

73,
Don W3FPR

> -----Original Message-----

>
> 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
>
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11:55 AM