5W Mod?

[Jim AB3CV]

I saw a note on the K2 schematic about improving efficiency at 5W levels and
it suggesting go to a "modifications section."

I can't find any such section in my Manual or the one online.

Where can I find this?

73

jim ab3cv

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[Don Wilhelm-3]

Jim,

You have sharp eyes!

That mod is simply a change in the number of turns on T4 as indicated on the
schematic.

BUT CONSIDER CAREFULLY:
This change will improve the efficiency at the 5 watt level and below, but
the efficiency will be decreased for power levels above 5 watts.  In
addition, a K2 having this mod should not be used in SSB or any of the data
modes - in other words it should only be applied to a 'CW-only QRP-at-5
watts or below' K2.

If you are going to operate on battery power at less than 5 watts with a CW
only capable K2, then you may want to make the change - otherwise, don't
consider it.

Since most folks want to add the KSB2 option and operate at higher than 5
watts, and possibly add the KPA100, the information has been dropped from
the manual - it remains only on the schematic.

73,
Don W3FPR

> -----Original Message-----
>
> I saw a note on the K2 schematic about improving efficiency at 5W
> levels and
> it suggesting go to a "modifications section."
>
> I can't find any such section in my Manual or the one online.
>
> Where can I find this?
>
> 73
>
> jim ab3cv
>

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1:23 PM

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[Randy Rathbun NV0U]

Hrm... I don't see it in the current manual... but it is online in  
REV C of the K2 manual. Section 9, page 100.

To save you time though, just remove one turn of the 3-4 winding on  
T4. I did this to #1981 and saw an immediate improvement - went from  
my K2 battery going dead with 20 minutes to go in the ARS Sprint to  
being able to go 2.5 hours.

Amazing what just one turn of wire will do!

On Feb 13, 2007, at 8:37 AM, Jim Miller wrote:

> I saw a note on the K2 schematic about improving efficiency at 5W  
> levels and
> it suggesting go to a "modifications section."
>
> I can't find any such section in my Manual or the one online.
>
> Where can I find this?
>
> 73
>
> jim ab3cv
>
> _______________________________________________
> Elecraft mailing list
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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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> Elecraft web page: http://www.elecraft.com

Randy Rathbun NV0U
[hidden email]
K2 #1981 KX1#1318
QRPARCI #10776, ARS #895, FPQRP #1292, KCQRP #1


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[Jim AB3CV]

Hi Don

Thanks for the quick reply. I'll leave it as is for now.

73

jim ab3cv
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