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K3: VFO A Tuning Freeze problems

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John K3TN

K3: VFO A Tuning Freeze problems

Back in March, VFO A on my 2 month old K3 froze up. Back to Elecraft for about 6 weeks, but the shipping seemed to cure the problem before it got there, and it worked fine when I got it back - until last night.
Turning VFO A knob causes display to flicker last digit but not QSY. Using RIT knob will change VFO frequency and display, VFO B knob changes VFO B, computer control will QSY both VFOs.

Elecraft had mentioned maybe computer control hangup on my end was the problem, but disconnected computer and serial cable from K3 and restart - same problem. Elecraft had also mentioned could be a board seating problem, and since I was annoyed at this unreliable K3, I did the tried and true "one inch drop on desk" test - which cured the problem, for now anyway.

I've emailed Elecraft support and I guess this time I'll open the K3 up to reseat the boards (vs. wait out Elecrafts 4-6 week repair backlog) but figured I'd check if anyone else has seen the same problem with any other potential solution.

John K3TN

Stan Gibbs, KR7C

Re: K3: VFO A Tuning Freeze problems

John,
The behavior you describe sounds similar to the temperature sensitivity problem (>39C) that I had with my recently minted K3. Turned out to be a bad encoder. Elecraft sent me a replacement, and it is humming along nicely now.

73, Stan - KR7C

73, Stan - KR7C

Stan Gibbs, KR7C

Re: K3: VFO A Tuning Freeze problems

If you are comfortable disassembling the front panel, you can also check that the encoder socket is making good tight contact with the encoder pins.

73, Stan - KR7C

73, Stan - KR7C

John K3TN

Re: K3: VFO A Tuning Freeze problems

In reply to this post by Stan Gibbs, KR7C

Hi, Stan - I guess that explains why when the K3 was out at Elecraft, Dale ran it thru 24 hours of temperature cycling. But that didn't recreate the problem out there. The shack is in the basement, pretty cool operating conditions and neither time did the failure occur during a long period of contest operating, so the thinking was the board seating issue, not the temperature sensitivity. But, I'll see what Elecraft comes back with.

Thanks for the input - Is the encoder just easy to replace?

73 John K3TN

-----Original Message-----
From: Stan Gibbs [via Elecraft] <[hidden email]>
To: John K3TN <[hidden email]>
Sent: Fri, Jun 11, 2010 9:34 am
Subject: Re: K3: VFO A Tuning Freeze problems

Stan - KR7C

View message @ http://elecraft.365791.n2.nabble.com/K3-VFO-A-Tuning-Freeze-problems-tp5167375p5167919.html
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Val-12

Re: K3: VFO A Tuning Freeze problems

Yes John, it's easy to replace. Even more, it's easy to test if the encoder
is the problem. By swapping the VFO A and VFO B encoders.

73 Val LZ1VB

>
> Hi, Stan - I guess that explains why when the K3 was out at Elecraft, Dale
> ran it thru 24 hours of temperature cycling. But that didn't recreate the
> problem out there. The shack is in the basement, pretty cool operating
> conditions and neither time did the failure occur during a long period of
> contest operating, so the thinking was the board seating issue, not the
> temperature sensitivity. But, I'll see what Elecraft comes back with.
>
>
> Thanks for the input - Is the encoder just easy to replace?
>
>
> 73 John K3TN
>
>
>
> John,
> The behavior you describe sounds similar to the temperature sensitivity
> problem (>39C) that I had with my recently minted K3. Turned out to be a
> bad encoder. Elecraft sent me a replacement, and it is humming along
> nicely now.
>
> 73, Stan - KR7C
>
> Stan - KR7C

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Stan Gibbs, KR7C

Re: K3: VFO A Tuning Freeze problems

In reply to this post by John K3TN

John,

The disassembly is pretty straightforward. Though, if you didn't build your K3, it might seem a bit more daunting. The process is just about like installing the sub-receiver in an already built K3.

I would expect that Dale would have checked the encoder-socket integrity when he had it on the bench.

73,

Stan

On Jun 11, 2010, at 8:00 AM, "John K3TN [via Elecraft]" <[hidden email]> wrote:

Hi, Stan - I guess that explains why when the K3 was out at Elecraft, Dale ran it thru 24 hours of temperature cycling. But that didn't recreate the problem out there. The shack is in the basement, pretty cool operating conditions and neither time did the failure occur during a long period of contest operating, so the thinking was the board seating issue, not the temperature sensitivity. But, I'll see what Elecraft comes back with.

Thanks for the input - Is the encoder just easy to replace?

73 John K3TN

-----Original Message-----
From: Stan Gibbs [via Elecraft] <[hidden email]>
To: John K3TN <[hidden email]>
Sent: Fri, Jun 11, 2010 9:34 am
Subject: Re: K3: VFO A Tuning Freeze problems

John,
The behavior you describe sounds similar to the temperature sensitivity problem (>39C) that I had with my recently minted K3. Turned out to be a bad encoder. Elecraft sent me a replacement, and it is humming along nicely now.

73, Stan - KR7C

Stan - KR7C

View message @ http://elecraft.365791.n2.nabble.com/K3-VFO-A-Tuning-Freeze-problems-tp5167375p5167919.html
To unsubscribe from K3: VFO A Tuning Freeze problems, click here.

View message @ http://elecraft.365791.n2.nabble.com/K3-VFO-A-Tuning-Freeze-problems-tp5167375p5168030.html
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73, Stan - KR7C

Don Wilhelm-4

Re: K3: VFO A Tuning Freeze problems

While disassembly is straightforward, there are a few "helps" that are
handy, such as removing the screw from the 2D connector on the RF Board,
that one is not intuitive.
Fortunately there a several mod instructions that detail the removal of
the front panel and the DSP board so you can get to the encoders -
download the instructions for the DSP Upgrade board.

73,
Don W3FPR

Stan Gibbs wrote:

> John,
>
> The disassembly is pretty straightforward. Though, if you didn't build your K3, it might seem a bit more daunting. The process is just about like installing the sub-receiver in an already built K3.
>
> I would expect that Dale would have checked the encoder-socket integrity when he had it on the bench.
>
> 73,
> Stan
>
>