K3 - internal TX PWR meter accuracy?

[ON4WIX]

Hi group,

I was just wondering if anyone has done TX power measurements with precision
measuring gear and compared these measurements against the K3's internal
indication of the output power?
Just curious here. The K3/100 is advertized as a 100W transceiver (or should
that be "100W class"?) and the power control on my unit goes up to 120W.
With the PWR cranked up to 120W the K3's bargraph meter does indeed show
120W output. The only external measuring tool I have is one of those
cross-needle meter (Daiwa CN801H) which I know displays the output power a
few % low into a known good dummy load but I've never been in a position to
accurately determine just *how much* low. The Daiwa's spec sheet mentions
10% FS excursion error so that would translate into a 20W uncertainty at the
200W meter scale setting.
Any input would be much appreciated. I know that there will be no
discernible difference on the receiving end when going from 90W to 110W but
as they say... inquiring minds want to know.

73 es tnx

Glenn ON4WIX
K2/100 #5361
K3/100 #192

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[Bill W4ZV]

ON4WIX wrote

I was just wondering if anyone has done TX power measurements with precision
measuring gear and compared these measurements against the K3's internal
indication of the output power?

Using N8LP's LP-100 (factory calibration) after calibrating at 50W per the manual:

Band        Max Power (set to 120W)

160          110.0
80            111.7
60            112.8
40            105.0
30            111.9
20            111,7
17            110.5
15            109.7
12            111.1
10            106.9
6              109.7

"Power accuracy is better than 5% at any frequency from ~1W to maximum, 3% typical with NIST traceable factory calibration"

http://telepostinc.com/lp100.html

73,  Bill  W4ZV

[Ken Wagner K3IU]

Hi Glenn:

Without claiming accuracy to any traceable standard, I just fired up my
trusty old 100 MHz HP 1740A O-scope, calibrated the display to the
built-in 1 volt calibration standard, and measured the P-P voltage into
a 51 ohm resistance (no measurable reactance). At 100 watts commanded
and indicated on the K3 (#202), I measured about 202v P-P. That
translates to about 100 watts. With the K3 set for 120 watts, I measured
about 220v P-P, which is about 119 watts. With the K3 set for 90 watts,
I measure about 192v P-P which is about 90 watts.

So... I would say that the K3 does a pretty good job in producing the
commanded power.

73,
Ken K3IU
Portsmouth, RI

ON4WIX wrote:

> Hi group,
>
> I was just wondering if anyone has done TX power measurements with
> precision measuring gear and compared these measurements against the
> K3's internal indication of the output power?
> Just curious here. The K3/100 is advertized as a 100W transceiver (or
> should that be "100W class"?) and the power control on my unit goes up
> to 120W. With the PWR cranked up to 120W the K3's bargraph meter does
> indeed show 120W output. The only external measuring tool I have is
> one of those cross-needle meter (Daiwa CN801H) which I know displays
> the output power a few % low into a known good dummy load but I've
> never been in a position to accurately determine just *how much* low.
> The Daiwa's spec sheet mentions 10% FS excursion error so that would
> translate into a 20W uncertainty at the 200W meter scale setting.
> Any input would be much appreciated. I know that there will be no
> discernible difference on the receiving end when going from 90W to
> 110W but as they say... inquiring minds want to know.
>
> 73 es tnx
>
> Glenn ON4WIX
> K2/100 #5361
> K3/100 #192
>

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