RE:Question about K2 power meter

[Vk2NU]

Jeff,

This variation in power out during tuning seems quite normal to me, and my
K2(100) does exactly the same..

It never used to bother me but I recently bought a Emtron DX-1 amp, and it
makes tuning the amp pretty tricky.. I only need about 30w to drive the amp
to full output, but during tune up the power out from K2/100 will creep up
and trip out the Overdrive on the amp. It would be nice to just dial up the
required power from the K2 you wanted and get it, but I suppose I'll just
have to live with this little quirk. I still wouldn't trade K2 for another
radio!!

David, VK2NU




Date: Sun, 22 Apr 2007 20:50:38 -0700
From: "Jeff Kinzli N6GQ" <[hidden email]>
Subject: Re: [Elecraft] Question about K2 power meter
To: [hidden email]
Cc: Elecraft Mail Posting <[hidden email]>
Message-ID:
        <[hidden email]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi Don,

Thanks for the replies.

To answer your questions, the problem occurs into a dummy load.

I set the base K2 (without KPA100 connected) to 5.0W, and then TUNE,
and it starts at 5.0W and heads upwards to 5.7-6.0W (read from the
display, as well as the S-meter). After about 10 seconds in TUNE, it's
up to 5.7 or 6W and the next LED on the S-meter is starting to flicker
some.

Moving the power knob will allow me to bring it back to 5.0W, but the
next TUNE will see the power climb back up again.

I'm not sure if I should still be looking on the RF board at this
point, or start focusing on the control board...?

Thanks, 73,

Jeff

 

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[Don Wilhelm-3]

David,

If your amp only requires 30 watts for full drive AND it is truly
linear, you should be able to tune it successfully with a 5 to 10 watt
input where the power is a bit more steady and then increase the level
to obtain full output.  Just a suggestion.

If the variation is quite bothersome, your K2/100 may be a candidate for
increasing the value of R98 (on the bottom of the RF Board) to slow down
the power variation.  If you increase it too much, the power output on
the higher bands may decrease (check that with the basic K2, not with
the KPA100 powered).  In most cases, about 1k is the upper limit for the
value, but if your K2 has greater gain than the average, you may find
success with even higher values.  It is easiest to substitute a 2k pot
for R98 when testing for the best value, then measure the pot resistance
and put in the nearest fixed value resistor.

This procedure is listed on the Elecraft website - in Builder's
Resources IIRC.

73,
Don W3FPR

David Douglass wrote:

> Jeff,
>
> This variation in power out during tuning seems quite normal to me, and my
> K2(100) does exactly the same..
>
> It never used to bother me but I recently bought a Emtron DX-1 amp, and it
> makes tuning the amp pretty tricky.. I only need about 30w to drive the amp
> to full output, but during tune up the power out from K2/100 will creep up
> and trip out the Overdrive on the amp. It would be nice to just dial up the
> required power from the K2 you wanted and get it, but I suppose I'll just
> have to live with this little quirk. I still wouldn't trade K2 for another
> radio!!
>
> David, VK2NU
>
>
>
>
> Date: Sun, 22 Apr 2007 20:50:38 -0700
> From: "Jeff Kinzli N6GQ" <[hidden email]>
> Subject: Re: [Elecraft] Question about K2 power meter
> To: [hidden email]
> Cc: Elecraft Mail Posting <[hidden email]>
> Message-ID:
> <[hidden email]>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hi Don,
>
> Thanks for the replies.
>
> To answer your questions, the problem occurs into a dummy load.
>
> I set the base K2 (without KPA100 connected) to 5.0W, and then TUNE,
> and it starts at 5.0W and heads upwards to 5.7-6.0W (read from the
> display, as well as the S-meter). After about 10 seconds in TUNE, it's
> up to 5.7 or 6W and the next LED on the S-meter is starting to flicker
> some.
>
> Moving the power knob will allow me to bring it back to 5.0W, but the
> next TUNE will see the power climb back up again.
>
> I'm not sure if I should still be looking on the RF board at this
> point, or start focusing on the control board...?
>
> Thanks, 73,
>
> Jeff
>
>  
>
> No virus found in this outgoing message.
> Checked by AVG Free Edition.
> Version: 7.5.463 / Virus Database: 269.5.9/773 - Release Date: 22/04/2007
> 8:18 PM
>  
>
> _______________________________________________
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> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
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>
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>
>

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