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K1 Problems

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Stephen Roberts

K1 Problems

I'm suddenly out of a signal. I get hiss but no signal. I'm using a k1 fil 2 40/20 board.

I was getting weak gain on the 40m side so went in to peak the L1/L2 L5/L6 Inductors.
I messed about with them but was unable to peak them as I heard no change in the
volume of the hiss.

I also tried C2 Gain tweak and not joy there either. I hear no change in the hiss volume
as I turn it.

I rigged up my 7300 with a dummy load and xmitted on 7050 and 14050 and heard a signal
but still no effect by changing L1/L2 or L5/L6

I pulled the band board looking for any issues with soldering or whatever and found
nothing. Put the board back in and now I get zip. No receive at all, just hissing.

It was working fine yesterday although I felt the gain was very low and needed adjustment
which led me to this point in time.

Suggestions on how to get it going again?

73
Steve, W1SFR

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VE3NR

Re: K1 Problems

Hi Steve,

Is the problem on both 20 and 40? If only one band check the band
crystal on the filter board.

C2 on the filter board is a fixed cap - no tweaking! ;-)

Also check connectors J6 and J7 on filter board. Bad connection - use
some DeOxit5 cleaner.

Start with alignment according to the manual, if you haven't done that.

Good luck!

Bert VE3NR

On 2020-06-20 15:47, Stephen Roberts wrote:

> I'm suddenly out of a signal. I get hiss but no signal. I'm using a k1 fil 2 40/20 board.
>
> I was getting weak gain on the 40m side so went in to peak the L1/L2 L5/L6 Inductors.
> I messed about with them but was unable to peak them as I heard no change in the
> volume of the hiss.
>
> I also tried C2 Gain tweak and not joy there either. I hear no change in the hiss volume
> as I turn it.
>
> I rigged up my 7300 with a dummy load and xmitted on 7050 and 14050 and heard a signal
> but still no effect by changing L1/L2 or L5/L6
>
> I pulled the band board looking for any issues with soldering or whatever and found
> nothing. Put the board back in and now I get zip. No receive at all, just hissing.
>
> It was working fine yesterday although I felt the gain was very low and needed adjustment
> which led me to this point in time.
>
> Suggestions on how to get it going again?
>
> 73
> Steve, W1SFR
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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Don Wilhelm

Re: K1 Problems

In reply to this post by Stephen Roberts

Steve,

The quickest way to do the alignment is to use an RF Probe or an
oscilloscope with a 10X probe.

First probe band board P1 pin 6 and peak for maximum RF on both bands.
The can be done in receive.
Then connect a dummy load and do a TUNE at about 1.5 watts.
Connect a probe to band board P2 pin 8. First on band 1, adjust L5 and
L6 for a peak - then refine the adjustment of L1 and L2 to maximize that
peak.
Do the same for Band 2 - adjust L7 and L8 for a peak, and then refine
the adjustment of L3 and L4.

Do you have power output? refine the adjustment of L7 and L8 on Band 2
and adjusting for maximum power - an external QRP wattmeter is handy for
that step.

Switch to Band 1 and refine the adjustment of L5 and L6 for maximum
power output.

When you have done that, the band board has been aligned the best it can
be. If you still have a receive problem it is somewhere other than the
band board.

I am not sure what you mean by "C2 Gain tweek" -- C2 is a fixed
capacitor in the VFO. If you meant C20, then that shifts the BFO, and
it should be set to center the signal in your receive passband.
You can adjust C20 - while receiving your local signal, adjust the VFO
to maximize the signal, without regard for the pitch (do this with the
narrowest K1 filter set). After doing that, adjust C20 so that you hear
the signal at your preferred pitch. Make sure the sidetone (in the
menu) is set for that same pitch.

73,
Don W3FPR

On 6/20/2020 3:47 PM, Stephen Roberts wrote: