[Elecraft] K1 VFO frequency does not change

[Don Wilhelm]

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]" <ml-node+s365791n7570316h63 at n2.nabble.com> 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.
>>>
>>>
>
>
>
> --
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