Strange K2 Failure Mode

[Jim Brown-10]

I bought a k2/100 from someone on this list several months ago, and
shipped to my remote QTH in CA. Just got out here to play with it
last weekend. It works fine on 160, but on 40 (and probably other
bands, haven't had time to check) the tuning knob tunes makes the
frequency readout change but the transmitted frequency (as observed
on another radio) doesn't.  The readout said 7002 kHz, but the
transmitted (and receive) freq was around 7070.

Any ideas what could be causing this?  Some operational settings I'm
forgetting about?

Other "glitches:"  

Tuning knob is VERY stiff compared to my own K2. Don't have tools
with me to work on it here to diagnose cause.

Strong transients when the RF gain knob is turned (sounds like DC on
the pot from a leaky cap).  Causes the AGC line to essentially mute
the radio for a second or so, then recovers to where the knob sets
it.

Any ideas on these things?  

Jim K9YC


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[n6wg]

Jim
>From your description, it sounds like you are in SPLIT mode.
Check the manual for directions.
Good luck and 73
Bob N6WG

-------------- Original message --------------

> I bought a k2/100 from someone on this list several months ago, and
> shipped to my remote QTH in CA. Just got out here to play with it
> last weekend. It works fine on 160, but on 40 (and probably other
> bands, haven't had time to check) the tuning knob tunes makes the
> frequency readout change but the transmitted frequency (as observed
> on another radio) doesn't. The readout said 7002 kHz, but the
> transmitted (and receive) freq was around 7070.
>
> Any ideas what could be causing this? Some operational settings I'm
> forgetting about?
>
> Other "glitches:"
>
> Tuning knob is VERY stiff compared to my own K2. Don't have tools
> with me to work on it here to diagnose cause.
>
> Strong transients when the RF gain knob is turned (sounds like DC on
> the pot from a leaky cap). Causes the AGC line to essentially mute
> the radio for a second or so, then recovers to where the knob sets
> it.
>
> Any ideas on these things?
>
> Jim K9YC
>
>
> _______________________________________________
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> You must be a subscriber to post to the list.
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> Elecraft web page: http://www.elecraft.com 

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[Ron D'Eau Claire-2]

Jim, K9YC, wrote:

I bought a k2/100 from someone on this list several months ago...Just got
out here to play with it
last weekend....

Tuning knob is VERY stiff compared to my own K2.

tuning knob tunes makes the frequency readout change but the transmitted
frequency (as observed
on another radio) doesn't.  The readout said 7002 kHz, but the
transmitted (and receive) freq was around 7070.

Strong transients when the RF gain knob is turned (sounds like DC on
the pot from a leaky cap).  Causes the AGC line to essentially mute
the radio for a second or so, then recovers to where the knob sets
it.
----------------------

Ouch!

Re: Stiff Tuning. A problem that hasn't been mentioned in a long time now
that caused the K2 optical encoder to become very stiff is that some of the
fine "hairs" from the felt washer can get tangled in the shaft bearing.
They'll show up where the rotating shaft passes into the bushing around the
c-clip retainer. I was able to tease mine out tugging each strand with
tweezers while rotating the shaft to "unwind" each one. It took me about 15
minutes or so of patient work but, in the end, the encoder ran as smoothly
as before. I put a little "super glue" on the inner edge of the felt washer
to hold the hairs together. That fixed the problem for me.

Re: Frequency readout.  Assuming you aren't in SPLIT mode (in which case you
should see the xmit frequency on the K2 when you transmit), I'd run CAL PLL
and see how it behaves. If the firmware has been changed without doing that,
all sorts of strange tuning behavior can occur.

Re: Noisy RF Gain. Sounds like an abused pot.

Ron AC7AC



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[Jim Brown-10]

On Mon, 31 Jan 2005 10:33:18 -0800, Ron D'Eau Claire wrote:

>Re: Frequency readout.  Assuming you aren't in SPLIT mode (in which case you
>should see the xmit frequency on the K2 when you transmit), I'd run CAL PLL
>and see how it behaves. If the firmware has been changed without doing that,
>all sorts of strange tuning behavior can occur.

Not split -- checked that first. Further tests showed that the problem is only on 40
meters. Then tried CAL PLL on 40 meters, and got INFO 232. Tried it again on 30
meters, INFO 232 again.  
>
>Re: Noisy RF Gain. Sounds like an abused pot.

I'll replace the pot.

Thanks for the detailed rundown on the shaft stiffness.

Jim K9YC




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[Jim Brown-10]

On Wed, 2 Feb 2005 18:02:43 +0100, Tom Arntzen wrote:

>If the frequency counter cabel isn't connected to TP1 you will get
>the info 232 message.

Thanks. It WAS connected from the counter to TP1.

Jim


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