Bill,
Yes, that is a consequence of not driving the K2 into the ALC region.
The overall Tx gain of the K2 varies from band to band, and normally the
internal ALC takes care of flattening it out. When operating AFSK data
modes, the preferred operating procedure is to set the power higher than
your desired operating power and then bring up the audio input to
produce the power level that you want to operate with - by doing that,
your IMD is lower, but the ALC is not functioning and the power will
vary from band to band depending on the TX gain for that band.
Unfortunately, the K2 does not have the DSP IF like the K3, and
automatic compensation is not possible unless you are overdriving
something (and producing a higher Tx IMD than necessary).
73,
Don W3FPR
Bill Coleman wrote:
During the recent NAQP RTTY contest, as I changed bands I noticed a
lot of variation in the output of my RTTY signal as I changed bands.
On 80 and 40m, I needed lot less audio input to get full output (40w)
than on 20m, and a lot more on 15 and 10m.
This required a lot of attention. If I changed bands upward, then I
might only eke out a couple of watts. If I changed bands downward, I
could overdrive the rig into ALC action.
Is this normal and expected? I'm using the K2SB with RTTY mode, so the
audio compression is off.
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