<paraindent><param>left</param><color><param>0000,0000,0000</param>I almost
always read that one should not operate into the ALC
range in PSK31 [and I suppose most other sound card modes].
On the other hand, one of the outstanding characteristics of Ten
Tec rigs for the last few generations, has been ALC stabilized
output at any power level within the transmitter's power range.
I have always operated PSK just on the edge of ALC control. Is
that good or bad? Don't know...............so I decided to run a test
to see what effect ALC had on signal quality.</paraindent>
<paraindent><param>left</param>For the test, my main rig was Pegasus connected
to a dummy load
with a very short piece of wire clipped to the "hot" lead of the
D/L and the power output set at 30 watts in the TUNE mode. My
test receiver was an Argosy with about 4" of wire connected to
the antenna jack. I have a 20db user selectable atteuator in the
Argosy so I had that in line. With my Pegasus keyed and sending
PSK, I got a S9 reading on the Argosy, so I clearly was not
overloading it. Both radio's had computers attached running
Digipan. The interface between the Peg and my computer is a
home built isolator with a transformer, resistive attenuator and
trim pot level adjust. I leave the mic setting on the Peg just
where it is when I operate SSB. I adjust the output level slider
on the sound card to 50% scale. Then I adjust the trim pot on
the interface until I JUST come into the ALC range. I then make
any fine adjustments in transmit level with the sound card level
slider. OK, that's the setup.</paraindent>
<paraindent><param>left</param>The results of the test were quite interesting.
With the sound
card adjusted so the ALC light never illuminated, I saw IMD
readings on the receive channel of around -32 to -33db. When I
brought the sound card level up to the point where the ALC light
just illuminated solidly, I saw -30 to -31db! And when I opened
the sound card level to full output, putting the Peg into deep ALC
range, I still saw IMD levels in the -27 to -28db range! And the
waterfall confirmed the above readings by being almost text
book perfect at all settings of the level control.</paraindent>
<paraindent><param>left</param>So the answer to the question
is.....................not bad to run the
Pegasus/Jupiter lightly into ALC range on PSK. The transmitted
signal will be one you can be very proud of and you will enjoy
stable output power as the rig heats up during transmit cycles
and the level adjustment will not be critical.</paraindent>
<paraindent><param>left</param>Good luck and enjoy the benefits of a well
designed rig!</paraindent>
<paraindent><param>left</param>-73-</paraindent>
<paraindent><param>left</param>-Lee-</paraindent>
<underline><color><param>0000,8000,0000</param>WmLB@prefer.net</underline></color>
wrote:
<color><param>7F00,0000,0000</param>>
> I have been monitoring the Jupiter power thread and can only
> comment that I have NOT seen that at all.
>
> What I do see when I use my Jupiter for PSK31 is a very non-linear
> increase in power out as I increase mic gain. I normally keep my
> RF power at a maximum and use only the mic gain to control output.
>
> As I increase mic gain. the power out goes up in distinct steps 10
> - 25 watts at a time. It is most noticeable on the lower
> frequencies. On 40M as I increase mic gain, the power jumps from
> an indicated 35 watts or so with no ALC indication, to almost 90
> Watts with a blinking ALC lamp. There seems to be no "in between"
>
> The steps I see on 15 and 20 are smaller but, none the less, far
> from being a gradual increase.
>
> It look likes the mic gain control is the one that controls in
> incremental steps and not in a gradual linear way.
>
> Am I alone with this issue or not...</color>
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