[Elecraft] K2 carry handle and QRP TX alignment

[Ethan Miller K8GU]

Don,

Great---thanks for the explanation!  This is exactly the procedure I
followed, but I did inadvertently move beyond the peak on the high
bands---those caps are a bit touchy.  I resolved it by doing just as
you suggested and the peak was easily achieved.  Just noting the
curiosity, that's all.

73,

--Ethan, K8GU/3.


On Fri, Feb 7, 2014 at 10:05 AM, Don Wilhelm <w3fpr at embarqmail.com> wrote:
> Ethan,
>
> The reason you are to first tune the BPF during receive is to get them close
> to the correct settings.
> You should find the peak during transmit close to the peak observed during
> receive.
> Certainly some of the BPF inductors and capacitors could be tuned to an
> improper mixer product if adjusted farther from the correct point.  You have
> the VFO frequency which is 4913 kHz away from the correct frequency and any
> harmonic of the BFO that could be present in the RF content prior to the
> BPF.  There will also be other mixing products that you could tune the BPF
> to (but you shouldn't).  The purpose of the BPF is to eliminate the
> undesired mixer products.
>
> When tuning the BPF on TX, start with the power set between 1.5 and 2 watts.
> If it climbs above about 5 watts, exit TUNE and re-enter to bring the power
> down again and continue to find the peak.
>
> 73,
> Don W3FPR
>
>
> On 2/7/2014 9:00 AM, Ethan Miller K8GU wrote:
>>
>> All,
>>
>> I breathed life into K2/10 #7372 (love that serial number) last night.
>>   This is going to be fun little radio despite being a 15-year-old
>> design!
>>
>> I noticed one thing that I wanted to ask the assembled experts here:
>> When peaking the TX BPF capacitors, there was a perceptible and
>> easily-found peak; but, if I got off the peak too far, the transmitter
>> power would increase rapidly to >10 watts as I tuned in the wrong
>> direction.  This must be normal or expected?  I did not monitor the
>> transmitter spectrum while doing this, so I don't know if it's a loud
>> spur that's normally suppressed or an amplifier somewhere is
>> conditionally-stable?
>>
>>
>



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