[Elecraft] K2 Output on 10 Meters

[Ron D'Eau Claire]

 Roy Morris  W4WFB wrote:

> I have heard some say their output exceeds 10 watts on 10 meters.  Under
what
> conditions was this measurement made?

> 1.  What was the voltage showing in the voltage/current display mode?

12.6 volts at 2.58 amperes

> 2.  Was the supply voltage increased to 14.4V. to allow for the .6V drop
in
> the K2?

No. The voltage shown on the K2 Display is 13.3 volts in receive. It's a
nominally 13.8 vdc fixed output supply.

> 3.  What was the power control set to?  (My control will not display
higher
> than 10 watts on 10 meters.)

P=15.2 watts, which all K2's should show when the POWER is set to maximum.
That is the "requested" power.  In normal operation, the ALC circuits in the
K2 adjust the gain of the r-f stages to produce the power requested. In TUNE
mode, that power control circuitry is disconnected and what you see is the
power the K2 is measuring at the output. On mine it is 12.2 watts output in
TUNE.  Your comment leads me to believe that you are seeing the limit of 10
watts when you are in TUNE.

> 4.  Was this measured with an accurate wattmeter into a 50 ohm (dummy)
load?

Good dummy load. Typical "ham" wattmeter (MFJ) on 30 watt scale says 13
watts. That corresponds  very well to the 12.2 watts reported by the K2, I
believe. I expect about 20% accuracy from most of  the 'good' r-f wattmeters
out there. If a wattmeter is better than that, it is a rather expensive one
(e.g. Bird, etc.) or a good design that has been very accurately calibrated
against a known precision meter.
>
> I want to make sure my K2 is ready for prime time to accept the KPA100 and
> put out 100 watts on 10 meters.

Elecraft specs the K2 at 10 watts output, and you should see that. The
Elecraft specs are conservative, and most ops get an extra watt or two. 10
meters is typically the band with the lowest output. It looks like you are
just meeting specs, assuming that your metering is accurate.

The Elecraft builder's resouces on the Elecraft web site offer a couple of s
imple "tweaks" that can add a watt or more to your 10 meter output. One of
them involves simply lifting up one of the toroids (T4?) a fraction of an
inch from the PCB.

It's good to keep things in perspective too. For example, the difference
between 10 and 11 watts output is the same as the difference between 100 and
110 watts output, as far as what other ops will hear. It a VERY SLIGHT
difference that, by itself, is simply not audible on the air. We're talking
about 0.4 dB difference, or (on most S-Meters) a difference of 1/15th of an
S-unit!

Ron AC7AC
K2 # 1289