160M problem

[Tom Althoff]

I was just testing out #1117 on 160M.  

Symptoms:
Max power output 7W
Low background noise compared to 80M (80 = S3 background, 160 nothing but 1 LED on big static crashes)

If I transmit a string of dits at 1W and listen on another radio, I have to hunt to find the signal.   It is at 1883.00.   I can transmit from 0000.00 on the dial to 1882.00 and the transmitted signal remains on 1883.00.  

As soon as I get to 1833.00 the transmitted signal follows the dial freq.

Almost sounds like the PLL is not locking below 1833.00.  

I suspect I'll need to do a full alignment to have some idea if there is a problem with the radio or if it's just misaligned.

This is just a preliminary examination of the radio....I haven't started any formal troubleshooting procedure yet.

Tom K2TA

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[Tom Althoff]

Ok...I'm in troubleshooting mode now.

VCO voltage at left side of R30 on 80M is correct (2.2 - 6 volts at either
end of
band).   On 160 I have to turn L30 clockwise a turn or so to get it in range
but then the PLL unlocks at 3800Khz.

Upon closer inspection it appears someone's been chasing this demon down
prior to my taking ownership of #1117.  That person is NOT the person who
wired #1117 originally!   The 160M, SSB and Noise Blanker were added by a
different ham at a later date.   I suspect this unit has never worked right
on 160M.

C68 is a 10pf as per the 160M mod BUT on the underside of the RF board there
is an additional 6pf tacked in parallel for a total of 16pf at C68.

C75 is a 450pf (close to the 470pf as per the 160M mod) BUT there is a 50pf
in parallel with it on the underside for a total of 500pf (again close to
the 470pf but on the high side this time).

Does anyone recognize these added componants from some other valid mod that
might not be mentioned in any of the K2 docs or addendums?

If not...I'm pulling the extra capacitance out and starting from there.

Tom K2TA
----- Original Message -----
From: "Tom Althoff" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, October 28, 2004 6:26 PM
Subject: [Elecraft] 160M problem


I was just testing out #1117 on 160M.

Symptoms:
Max power output 7W
Low background noise compared to 80M (80 = S3 background, 160 nothing but 1
LED on big static crashes)

If I transmit a string of dits at 1W and listen on another radio, I have to
hunt to find the signal.   It is at 1883.00.   I can transmit from 0000.00
on the dial to 1882.00 and the transmitted signal remains on 1883.00.

As soon as I get to 1833.00 the transmitted signal follows the dial freq.

Almost sounds like the PLL is not locking below 1833.00.

I suspect I'll need to do a full alignment to have some idea if there is a
problem with the radio or if it's just misaligned.

This is just a preliminary examination of the radio....I haven't started any
formal troubleshooting procedure yet.

Tom K2TA

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Post to: [hidden email]
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Subscriber Info (Addr. Change, sub, unsub etc.):
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Elecraft web page: http://www.elecraft.com

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Post to: [hidden email]
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Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft   
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Elecraft web page: http://www.elecraft.com