Tom,

To me, if you're within 10 watts either way, you're in the ballpark.  I'm 
not surprised that your readings are lower with the dummy load.  You're 
probably getting less reflected power, which means the meter is less 
confused about your actual power output.

Regarding the TW-1, I'm not sure you'll be able to make it any more accurate 
than it is, and quite frankly, I wouldn't bother even if you could.  If 
you're really concerned about your actual power output, hook up a Byrd meter 
and run the rig on a dummy load where you know you'll get a 1:1 SWR.  Other 
than that, I doubt you'll ever get a truly accurate reading; there are just 
too many variables that you can't control.  Besides, you'll never get a 
signal report that reflects that ten watts of difference (if it even means 
anything, which I suspect it doesn't).  It's very easy to get caught up in 
meaningless number games when it comes to output power.

Steve

----- Original Message ----- 
From: "tom behler" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, June 30, 2011 18:08
Subject: Wonder if these TS590 output power readings sound reasonable?


> Hi, all.
>
> Well, I have done some fairly extensive testing on the output power 
> readings
> for my TS590, and I wonder if what I'm seeing is what can be reasonably
> expected.
>
> Let me start with some general background:
>
> First of all, I took the voltage reading from my Astron RS35 linear power
> supply, and it read about 13.8 volts--right where I had hoped it would be.
>
> Then, I took a bunch of SWR and output power readings, on various bands 
> and
> frequencies, using my DXCC and Windom antennas.
>
> My best readings were found on 80 meters, where I could get my Alpha Delta
> DXCC antenna down to an SWR of 1.2 to 1.  I can get reasonably low SWR's 
> on
> other bands and frequencies with the DXCC or my Windom, but without an
> antenna analyzer, the 80-meter frequency with the DXCC was the lowest I
> could get.  All readings were taken with the internal automatic antenna
> tuner off.
>
> With a 1.2 to 1 SWR reading on 80 meters, my LDG Tw1 gave me a forward 
> power
> reading of 95 watts, and a reflected power reading of 1.2 watts.
>
> Just for kicks, I had my sighted XYL look at the watt meter on the TS590,
> and she said it was pegged at the maximum 100 watt level.  My XYL also
> approximated my output power using the meter on my Tentech 238A manual
> tuner, and she said it looked to be just a hair below 100 watts.
>
> Interestingly, for reasons which I can't quite figure out, my output power
> reading was slightly lower when I used a dry dummy load.  Specifically, 
> the
> readings ranged from 90 to 93 watts with the dummy load connected after 
> the
> TW1.
>
> Do these readings seem reasonable?
>
> Actually, I'm wondering if my TW1 is slightly off callibration.
>
> If so, does anyone know how or whether the TW1 can be callibrated?
>
> I'd be interested in any thoughts anyone has.
>
> 73 from Tom Behler:  KB8TYJ
>