John,
While you are waiting for the 1SV149 to arrive, solder a 1N400x diode (X
= 1 thru 7) in its place and see if you can achieve any variation in the
frequency. Make certain the cathode is oriented to connect to the RP2
pin 2 and C2 junction.
It may not give you correct range, but it should shift the frequency.
73,
Don W3FPR
On 2/24/2013 7:31 PM, John Reed, W8DE wrote:
Don,
thanks so much for your advice. The board traces in that area all check out
good. I'll email a request to elecraft for a new D3.
If it really is bad, it makes me wonder about the 1SV149 diodes in the crystal
filter circuit. I don't know how I would tell if those are functioning
correctly.
73,
John W8DE
On Feb 24, 2013, at 4:25 PM, "Don Wilhelm-4 [via Elecraft]"
<[email protected]> wrote:
John,
Yes, that would strongly indicate that D3 is faulty. It is good that
you confirmed RIT does change the frequency.
I don't think you will find one locally, but an email to
[hidden email] should bring you one quickly in the mail.
Since a bad D3 is a rarity, you might also want to check for board
continuity with your DMM. Check to see that you have the same voltage
variation on one lead of C2 - that will confirm that D3 is connected to
C2. The other lead of C2 cannot be tested with voltage, so use your
ohmmeter to check for continuity between the other lead of C2 and L1.
Should you find the board has an open trace (also a real rarity), repair
it with a wire. Elecraft would send you a new board, but you already
have enough work in that board to warrant repairing it with a wire.
73,
Don W3FPR
On 2/24/2013 3:27 PM, John Reed, W8DE wrote:
Don,
C2 and D3 look to be properly installed. I confirmed orientation from a 1SV149
data sheet just in case I mis-read the instructions.
I can adjust receive frequency with RIT, so it looks like the D4 control is
working.
Since the D3 voltage is varying from 0v to 5.888v with the tuning pot, but
there is no change in frequency, I'm starting to suspect a bad D3. I don't
know of anyway to check it in circuit -- at least with the tools I have. I'll
see if I can pick up a 1SV149 locally. I considered swapping it with D6, but I
don't think I can remove it without damaging it.
--
View this message in context:
http://elecraft.365791.n2.nabble.com/K1-VFO-frequency-does-not-change-tp7570276p7570320.html
Sent from the Elecraft mailing list archive at Nabble.com.
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