K2: Low 10M Output

[Michael J. Linden]

  I've just completed the alignment procedure for my K2 and now find
that the radio can not achieve 10w across the 10m band. All other bands
easily achieve 10w from one end to the other. I'm running the K2 off of
a 13.8V supply. The K2 reports 13.2V on receive and 12.7 - 13.1V on 10m
transmit (varies with current drawn). Here are the 10m numbers as
reported by the K2 into a 50 Ohm load:
 
11.2w @ 28,200 kHz, 2.5A
6.9w  @ 29,000 kHz, 1.9A
1w  @ 29,700 kHz, 0.96A
 
  I'd say that T2's primary winding covers close to 90% of the core, its
secondary covers about 50% of the core, and it sits about 1/8" above the
board. What else should I be looking at? Could this be a low-pass filter
problem?
 
  Thanks, Michael N9BDF
  K2 #4137
 
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[David Pratt-3]

The K2 specification in the manual states that the band is 28.0 to
28.8MHz, Michael.  Because of the design of the band pass filters,
transmitting outside that range will result in a lower power output.
I would say that your K2 is operating within spec.

73

David G4DMP

In a recent message, Michael J. Linden <[hidden email]> said....
>  I've just completed the alignment procedure for my K2 and now find
>that the radio can not achieve 10w across the 10m band.
.....
>11.2w @ 28,200 kHz, 2.5A
>6.9w  @ 29,000 kHz, 1.9A
>1w  @ 29,700 kHz, 0.96A
--
+-------------------------------------------------+
|  David M Pratt mailto:[hidden email]  |
|  Home Page: http://www.kippax.demon.co.uk       |
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[Tom Arntzen]

This looks pretty the same as I had recently before I installed KPA100.
The drop starts at about 28,700.
If you are over or near 10watts over 28-28,8 range you are OK.
BTW! KPA100 seems to be a bit wider before any drop is noticeable.
Tom LA1PHA

>>11.2w @ 28,200 kHz, 2.5A
>>6.9w  @ 29,000 kHz, 1.9A
>>1w  @ 29,700 kHz, 0.96A
> --
> +-------------------------------------------------+
> |  David M Pratt mailto:[hidden email]  |
> |  Home Page: http://www.kippax.demon.co.uk       |
> +-------------------------------------------------+
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[Don Wilhelm-3]

Michael,

The 10 mtr bandpass filter is likely set too low in frequency to cover the
entire 10 meter band.  Note that the speced 10 meter band is 28.0 to 28.8
mHz.

If you have need for coverage over more of the band, peak it using a
frequency higher than 28,200 kHz.  My suggestion would be to peak it at
28,500 or 28,700 kHz for starters.  You may not be able to achieve a full 10
watts over the entire band, but you should be able to achieve a reasonable
compromise from end to end.

After you re-peak the 10 meter bandpass, you will have to adjust the 12
meter trimmer caps again - the adjustable inductors are shared between these
2 bands.

73,
Don W3FPR


----- Original Message -----
From: "Michael J. Linden" <[hidden email]>
To: <[hidden email]>
Sent: Monday, October 25, 2004 11:25 PM
Subject: [Elecraft] K2: Low 10M Output

>  I've just completed the alignment procedure for my K2 and now find
> that the radio can not achieve 10w across the 10m band. All other bands
> easily achieve 10w from one end to the other. I'm running the K2 off of
> a 13.8V supply. The K2 reports 13.2V on receive and 12.7 - 13.1V on 10m
> transmit (varies with current drawn). Here are the 10m numbers as
> reported by the K2 into a 50 Ohm load:
>
> 11.2w @ 28,200 kHz, 2.5A
> 6.9w  @ 29,000 kHz, 1.9A
> 1w  @ 29,700 kHz, 0.96A
>
>  I'd say that T2's primary winding covers close to 90% of the core, its
> secondary covers about 50% of the core, and it sits about 1/8" above the
> board. What else should I be looking at? Could this be a low-pass filter
> problem?
>
>  Thanks, Michael N9BDF
>  K2 #4137
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

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