Leaving TP2 connected?

[Eddy]

Quick question regarding my 3000+ K2, I'm "struggling" to get the filters just right so can I leave TP2 connected all the time? So, I haven't noticed any adverse affects.....

This way I won't have to take the cover to try and new filter setting.

thanks and 73

ed

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[Vic Rosenthal]

The reason you are not supposed to do this is that the third harmonic of the BFO is picked
up and amplified, producing a spurious output just above the high end of 20m (I've
forgotten the exact frequency). I don't know about problems on other bands. I recall that
I checked and the spur was much stronger with the cable in TP2. Especially if you are
using a KPA100 or (worse) an external linear as well, you shouldn't do this!

On 4/15/2013 8:53 PM, Eddy wrote:

> Quick question regarding my 3000+ K2, I'm "struggling" to get the filters just right so can I leave TP2 connected all the time? So, I haven't noticed any adverse affects.....
>
> This way I won't have to take the cover to try and new filter setting.
>
> thanks and 73
>
> ed
>
> ______________________________________________________________
> Elecraft mailing list
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--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/

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[Don Wilhelm-4]

Ed,

If you are having trouble getting the K2 filters aligned, you might want
to refer to the information in the K2 Dial Calibration article on my
website www.w3fpr.com.  Use Spectrogram (or another audio spectrum
analyzer) to be able to see the filter passband.
You can download Spectrogram from the home page on my website.

Leaving the counter probe in the K2 should only be done with an
unamplified K2/10.  If you have the KPA100 or use an external amplifier,
remove the probe.

73,
Don W3FPR

On 4/15/2013 11:53 PM, Eddy wrote:
> Quick question regarding my 3000+ K2, I'm "struggling" to get the filters just right so can I leave TP2 connected all the time? So, I haven't noticed any adverse affects.....
>
> This way I won't have to take the cover to try and new filter setting.
>
>

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[jwin2485]

The counter probe is inside my k2/100 but not connected to TP2. However,
 it is still plugged into the control board. It's just parked along the
left side panel and grounded in a dummy jack in the back corner of the
 rig (as per on old tip by Tom, N0SS). Is there a chance of creating problems if left this way? I left it
 in primarily to keep from misplacing it when needed.

73 de WB4GLJ

--- On Tue, 4/16/13, Don Wilhelm <[hidden email]> wrote:

From: Don Wilhelm <[hidden email]>
Subject: Re: [Elecraft] Leaving TP2 connected?
To: "Eddy" <[hidden email]>
Cc: [hidden email]
Date: Tuesday, April 16, 2013, 8:36 AM

Ed,

If you are having trouble getting the K2 filters aligned, you might want to refer to the information in the K2 Dial Calibration article on my website www.w3fpr.com.  Use Spectrogram (or another audio spectrum analyzer) to be able to see the filter passband.
You can download Spectrogram from the home page on my website.

Leaving the counter probe in the K2 should only be done with an unamplified K2/10.  If you have the KPA100 or use an external amplifier, remove the probe.

73,
Don W3FPR


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[Don Wilhelm-4]

John,

That presents no problem at all.  The base K2 manual suggests that you
leave the probe in TP2 to allow you to adjust the filters at will, but
it also exposes the RF circuits to 3rd harmonic leakage from the BFO.  
With the K2/10 that does not normally produce spurious responses that
are objectionable,  But if the KPA100 or an external amplifier is added,
they can be stronger than allowable by the FCC.

My recommendation is to not leave the probe connected to either TP2 or
TP1.  It can remain connected to the control board as long as the tip
does not flop around and cause problems.  Securing the tip as suggested
by N0SS (SK) is a good addition.

73,
Don W3FPR

On 4/16/2013 11:39 AM, John Wingard wrote:
> The counter probe is inside my k2/100 but not connected to TP2. However,
>   it is still plugged into the control board. It's just parked along the
> left side panel and grounded in a dummy jack in the back corner of the
>   rig (as per on old tip by Tom, N0SS). Is there a chance of creating problems if left this way? I left it
>   in primarily to keep from misplacing it when needed.
>

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