[Elecraft] K3 low PEP Power on SSB

Tue Apr 29 12:52:49 EDT 2008

The real key is using an external audio generator into the mic 
input and seeing what comes out the other end using an 
oscilloscope. This removes all the issues with microphones and 
their setup.

I agree that antenna matching can make quite a difference to the 
results, that is why I took the time to build an accurate dummy 
load consisting of 30 1.5k 2W 1% tolerance metal film resistors.  

Measuring the load on a VNA (Vector Network Analyser) shows worst 
case 1-30 MHz VSWR as 1.05. So that should be good enough.

In real terms the variations seen in the Peak SSB TX signal are 
insignificant at the other end of a QSO, however if my old TS850S 
can get it right, I expect the same from my new K3.

Y.M.M.V

73
Stewart G3RXQ
On Tue, 29 Apr 2008 09:37:37 -0700, David Yarnes wrote:
> Hi All,
>
> I've been watching this thread and wondering if there truly is a 
problem.
> It seems to suggest there is, and Elecraft says they are looking 
into it
> with a firmware update pending.  But I can't help thinking that 
there are so
> many reasons why the problem could just possibly be in the 
setup.  The
> variation in reports seems to suggest this could also be an 
issue.  For one
> thing, if the antenna isn't correctly matched, I would think 
there would be
> some foldback.  But if you are getting full output on CW, you 
should get
> that on SSB as well.  But full output on SSB isn't that easy to 
observe.
> You may well be getting full output on SSB, but your meter won't 
necessarily
> disclose that.  This has been pointed out before.  I also wonder 
if the
> microphone settings are correct.  You may think some microphone 
gain
> setting, 10 for example, is sufficient, but just possibly it 
needs 12 or 15?
> Just a thought.
>
> Another thing could be the microphone itself.  In Mike's 
situation
> (discussed by him below) for example, he indicates that he took 
a stock
> microphone from his Kenwood TS-2000 and hooked it up.  I assume 
he is
> assuming that there is total compatibility with Kenwood 
microphones.  I
> don't know if that microphone is an electret, but if it is, I'm 
not sure it
> really is totally compatible.  The standard Kenwood wiring has 
the 8 volts
> or so on a different pin than the Elecraft uses.  I think the 
Kenwood is pin
> 5, and the Elecraft is pin 6--or maybe I have that backwards. 
 But there is
> a difference.
>
> I'm only suggesting these things as a possibility--for all I 
know everyone
> has fully considered all these issues and dealt with them 
correctly.   In my
> case, I am using the Elecraft Pro Headset (electret) via the 
back
> connectors.  As far as I can tell, I'm getting full output on 
SSB.  The only
> exception to that seems to be on the higher portion of 40 
meters, where I
> don't seem to be able to get quite 1:1 through the tuner.  My 
antenna is set
> for the CW portion, and so I get about 1.3 to 1 up near the high 
end.  It
> seems my SSB output is down somewhat when I operate there, but 
only
> slightly.  This is based on the RF output indication on the K3 
itself.  I
> may be making an erroneous assumption, but I attribute that to 
not being
> exactly matched.  My reports, though, are good.
>
> Dave W7AQK
> ----- Original Message -----
> From: "Mike Penkas" <mpenkas at comcast.net>
> To: <elecraft at mailman.qth.net>
> Sent: Tuesday, April 29, 2008 7:58 AM
> Subject: [Elecraft] K3 low PEP Power on SSB
>
>
> I disconnected all my outboard audio gear on the K3 and 
connected
> an Array Solutions Powermaster Meter and dummy load directly to
> the K3.  With the K3 set to 120 watts my keydown RF output on
> 20 meters reads 116 watts.
> I connected a stock hand mic that came with my Kenwood TS-2000
> to the front mic connector set to High.
> With Mic gain set to 15 and comp to 0 and all equalizer settings 
at 0
> I show a max of 75 watts.
> With the compressor turned on to a setting of 18, I show peaks 
of
> 110 watts with alc flickering between 3 and 5 bars.
> Monitored audio on a second receiver is very clean.
> Mike WA8EBM
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