On 23 May 2001, at 19:20, Robert Steele wrote:
>
> When operating digital modes such as PSK311 they say you should set
> the power output to about half max in order to avoid distortion so as
> to be sure that you are not radiating too broad a signal.
>
> I notice that when I set the power knob on the Jupiter to about 40%,
> then adjust the microphone gain so thaat ALC light just not come on
> when the TX light is on and PSK31 is idling, the forward power meter
> indicates about 17 watts, with the SWR meter at 1.1.
>
> Question: would I still be in the linear output range of the
> transceiver if I increased the power knob to 80 % and readjusted the
> mic gain so that the ALC light still is just below limiting? If I used
> fan cooling on the heat sinks would this be satisfactory for the
> transmitter?
>
> Thanks
> bob
>
Bob,
There is a description of how to set things in the Zakanaka Help
file, but here is the gist of it.
Run RTTY (AFSK), and adjust the microphone gain for half the
power you are running when you are in steady tone mode, while
using an AVERAGE reading meter (not peak). Leave the
microphone gain at that point for PSK31 as well. You should find
that the ALC light seldom comes on, or is dim. You should also
find that other PSK operators give you excellent IMD reports. Your
PSK AVERAGE power reading will be at about 70% of steady-tone
power.
Now, of course, you can run a linear when you chase P5 on PSK,
because you are sending a clean signal. Point that yagi northwest
and blast away.
Please let me know whether or not you verify this approach. Thank
you.
73,
Jan Ditzian
KX2A
kx2a@arrl.net
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