K2 10m Power Output

[Ben Hofmann K1NT]

Hello all,
 
I completed the transmitter alignment on K2 #4429 recently.  In checking the power output on all the bands I found that I can indeed get just over 10w on 10m at 28.2 MHz (the frequency used to peak the bandpass filters) as long as I am using a power supply.  Using a battery, I had too much voltage drop, and less power output.  When I tune up to 28.8 MHz, I can only get less than 9w output (using the power supply.)  Why does the manual instruct to use 28.2 MHz to peak the filters rather than 28.4 MHz which would be the center of the K2 band specification for 10m?  I would think using 28.4 MHz would give me higher output at the high end of the band probably at the expense of lower power at the lower end of the band.  Since the bandpass filter is shared between 10m and 12m, I don't know if doing the peak at 28.4 MHz would adversely affect 12m or not.  Any thoughts?  I'd like to get 10w minumum over the whole band if I can.  Should I try and get the power to be more even across t
 he band,
 or am I being too picky here?
 
By the way, I was very careful with T2 during construction.  Red winding occupies about 85% of core, and green winding about 50%.  It is spaced between 3/32 and 1/8" off the PC board.  I did not however interleave the windings on T4, I wound it as instructed in the manual.
 
-Ben  KB1AHR
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[Don Wilhelm-3]

Ben,

The place where one aligns the bandpass filter on 10 meters must depend on
the 10 meter operating that is anticipated.  If the interest is mainly CW,
the bandpass filter would be peaked at 28.2 MHz as stated in the manual --
OTOH, if more phone operation (or CW higher in the band) is more desirable,
then by all means peak the Bandpass at a higher frequency.  I often peak the
bandpass filter at 28.4 or 28.5 to provide more coverage over the band with
10 watts or more.  You will note that the output drops off more quickly (per
kHz) on the high end than at the low end, so I just balance things so I have
10 watts or more at both 28.0 and 28.8 - whatever the peaking frequency may
be to achieve that goal.

Yes, you will have to re-peak 12 meters after peaking 10 -- there is no
danger of running out of adjustment range on 12 meters.

73,
Don W3FPR

> -----Original Message-----
>
> I completed the transmitter alignment on K2 #4429 recently.  In
> checking the power output on all the bands I found that I can
> indeed get just over 10w on 10m at 28.2 MHz (the frequency used
> to peak the bandpass filters) as long as I am using a power
> supply.  Using a battery, I had too much voltage drop, and less
> power output.  When I tune up to 28.8 MHz, I can only get less
> than 9w output (using the power supply.)  Why does the manual
> instruct to use 28.2 MHz to peak the filters rather than 28.4 MHz
> which would be the center of the K2 band specification for 10m?
> I would think using 28.4 MHz would give me higher output at the
> high end of the band probably at the expense of lower power at
> the lower end of the band.  Since the bandpass filter is shared
> between 10m and 12m, I don't know if doing the peak at 28.4 MHz
> would adversely affect 12m or not.  Any thoughts?  I'd like to
> get 10w minumum over the whole band if I can.  Should I try and
> get the power to be more even across t
>  he band,
>  or am I being too picky here?
>
>

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