K2 low output on 80

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K2 low output on 80

Phillip Zminda
I recently noticed while on 80 cw with a watt meter attached, that my output on 80 cw  was only about 2 to 3 watts at the low end of the band, even though the drive setting was for about 12 watts. I can't say I that I have checked the output on 80 cw recently, so this may not be new. I built and aligned the K2 about a year ago and have the built-in tuner installed. I re-checked it with a dummy load and got the same results. If I tune to the center of the band the output goes up. At the high end, it also appears to drop off. Other bands seem OK. I intend to open it up and peak the alignment, but before I do that, is there anything else I should be looking for?

Thanks,

Phil N3ZP
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Re: K2 low output on 80

Don Wilhelm-4
Phil,

The first thing to check is the bandpass filter for 80 meters.  Check
that L5 is properly soldered and has a value of 33 uHy.  Recheck the BPF
peaking using a transmit power of 1.5 watts.

Normally, the response across 80 meters is rather flat, and I suspect
that you have a problem with the coupling element in the BPF, namely L5.

Another thing to check is the VCO voltage (R30 voltage) at both ends of
80 meters - if it drops below 1.5 volts at the low end or goes above 6.5
volts at the high end, you have a problem with the VCO range.

73,
Don W3FPR

Phil Zminda wrote:
> I recently noticed while on 80 cw with a watt meter attached, that my output on 80 cw  was only about 2 to 3 watts at the low end of the band, even though the drive setting was for about 12 watts. I can't say I that I have checked the output on 80 cw recently, so this may not be new. I built and aligned the K2 about a year ago and have the built-in tuner installed. I re-checked it with a dummy load and got the same results. If I tune to the center of the band the output goes up. At the high end, it also appears to drop off. Other bands seem OK. I intend to open it up and peak the alignment, but before I do that, is there anything else I should be looking for?
>
> Thanks,
>
> Phil N3ZP
>
>  
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