[TenTec] Re: Jupiter and PSK31

[WA3FIY]

<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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