Andrew,
During the initial build, it is important to peak the bandpass filters
using receive to be certain they are aligned in the correct bands - this
is especially important on the higher bands.
After doing that, the bandpass filters are peaked using transmit where
the peak is more easily observed.
If your K2 is working and you are simply doing a re-alignment, you may
skip the receive alignment and just do the TX alignment.
For observing the L34 peak, I use Spectrogram (or whatever FFT
application you will be using for the IF filter.BFO alignment). Use a
filter about 700 Hz wide, and tune the 7000 kHz birdie for the greatest
amplitude on the screen (at your chosen sidetone pitch) - the peak is
quite broad, but look on the right of the Spectrogram display (the
higher frequency content) and adjust around this broad peak point to get
the higher frequency noise to its minimum. That will give you the best
signal to noise ratio - which is the correct setting for L34. A DMM on
the K2 output cannot show you all that, but if you have no other tools,
it is one way to set L34.
That being said, it is best to align L34 after doing the IF filter
alignment so you can use the properly aligned filter during that step.
While you are building the K2 and doing the preliminary alignments as
you build, things are a little bit different than when building - you
will do a better job if you do the final alignment with the completed
K2, and the L34 alignment as I described is one example.
73,
Don W3FPR
On 12/29/2010 8:55 AM, Andrew Moore wrote:
> I'm doing a thorough realignment of my K2.
>
> I've done a RX-only alignment of the 40 meter bandpass filters by listening
> to a signal generator source while peaking L1 and L2. Could I gain accuracy
> here by using a DMM to monitor the AC voltage at the speaker output, peaking
> L1/L2 for max AC on the DMM? This is the method suggested (I believe in the
> K2 manual) for more sensitivity/accuracy when peaking L34 in an earlier
> stage of alignment.
>
> In a later stage, I tune L1 and L2 when in Tune mode, for max power output
> according to the K2's LCD.
>
> Which is the most accurate method -- monitoring with DMM in RX mode, or
> monitoring power output in TX mode? Or are they so close it just doesn't
> matter?
>
> Thanks,
> --Andrew, NV1B
>
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