Elecraft K2 IF Amp issue and loking for advice

[Cameron Francey]

Hi,

I was re-adjusting the IF amp peak on my K2, however (and I do remember having an issue at build time) there is no peak in the whole range of the inductor can.

Doing some investigation along with the circuit digram I think I have found my problem.


Across pins 1 and 8 of U12 I'm seeing the value of R111, which is about 5k5, but thats also in parallel with the winding of L34, so I'd have expected that to have measured just a few ohms or less.

So seems that my issue is an open circuit L34.  The only reason I noticed this was because side by side with my more recent K2 its not quite as sensitive.  On the plus side it does have a much lower noise floor.


So, my question is based around if anything would cause L34 to go open circuit?  I cant see anything in the circuit that might have caused excessive current or something similar.  All the solder work in that whole area is neat, and I didn't over-do the heat when installing it and the components all appear to be in the correct places.

It had worked, as I remember finding the peak at the time I built it, but then suddenly it wouldn't re-peak after that, but at the time I didn't think much more of it.


Should I just request L34, or is there something else I may need from others past experiences?



thanks in advance,

Cameron - AF7DK/GM7LQR



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[Don Wilhelm]

Cameron,

There is nothing in that circuit that would have zapped L34.  I would
just replace the inductor.

If you do not have good de-soldering equipment, L34 may be difficult to
remove.  I suggest destroying the present inductor if you have to, and
take it out one pin at a time (get the shield off first, then work on
the inductor).
Be careful not to damage the thru-plated holes in the RF Board, or you
will be in for a circuit re-wiring task.

73,
Don W3FPR

On 4/4/2017 4:49 PM, Cameron Francey wrote:
>

> Should I just request L34, or is there something else I may need from others past experiences?
>
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[Cameron Francey]

oops, forgot to reply all....


________________________________
From: Cameron Francey <[hidden email]>
Sent: Tuesday, April 4, 2017 2:16 PM
To: [hidden email]
Subject: Re: [Elecraft] Elecraft K2 IF Amp issue and loking for advice


Hi Don,

I suspected I was most likely a case of bad luck with a component so thanks for confirming that.  Yes, I was thinking ahead on how I would be removing it.  I thought about trying that approach and crushing it with pliers to get at each pin.  Being clear on three sides will make that a little easier.

De-solder braid and a de-soldering pump have been my tools of choice for the past 30 years.. I'll be sure to be really careful, so thanks for also mentioning that point.


I'll contact Elecraft and ask for the part.


thanks,

Cameron


PS, that was a fast response to my question, very much appreciated!

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