[Elecraft] K2- Is the Power display really representative of PEP?

[Ron D'Eau Claire]

Robin, you're measuring REQUESTED power, not the actual power. The actual
power is shown on the bargraph. 

The actual power appears on the LCD display ONLY in TUNE mode, not when you
key the mic. 

Check the ALC action on 10 meters. (Press and hold the RF/ALC button so the
screen says ALC briefly). Now key the mic and talk. At least one bar on the
bargraph - the bar on the extreme RIGHT end - should flicker when you talk
on 10 meters. 

The bargraph reads backwards when showing ALC so you won't forget which
meter mode you're in. The flickering bar says that he K2 is making all the
RF you are REQUESTING (by setting the POWER knob) and is beginning to back
down the audio gain automatically. (Within the limits of the circuits, the
more audio, the more RF output). 

You may see several bars flicker on 40 meters. The RF stages in the K2 have
more gain on the lower frequencies. Ten meters tends to be the band where
the output is lowest. Still, you should see ONE bar flicker when the POWER
control is set for 10 watts.

If you aren't seeing one bar flicker in ALC mode, then the K2 isn't making
the full 10 watts on ten meters. You can verify that by pressing RF/ALC
again to go back to "rf" monitoring and talking into your mic. You probably
won't see all the bars light up, indicating 10 watts on peak. 

Keep in mind that the RF output is "peak" reading, but the peaks may be very
brief. Normally you will see the last bar on the right flicker only slightly
at a full 10 watts.

Ron AC7AC




-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Robin Kiszka-Kanowitz
Sent: Sunday, November 07, 2004 9:09 AM
To: W3FPR - Don Wilhelm; elecraft at mailman.qth.net
Subject: Re: [Elecraft] K2- Is the Power display really representative of
PEP?


Hi and thanks for the answers so far,

To give a bit more detail...

I'm not using any antenna tuner in my K2, it's the basic K2 with SSB module
and battery pack, but for the power out measurements I'm using a DC PSU.
I've set the K2 to CW and keyed the microphone, with the Power turned full
clockwise...

The output reading is on the YS-60 is using the 20 watt scale. The dummy
load is true 50 Ohms, and this is what I get...

Band   Mhz            K2 LCD       YS-60
80m    3.500          15.2                18
40m    7.050          14.8                16.5
20m    14.200        14.8                14.5
17m    18.150        14.8                14.5
15m    21.200        14.8                12
10m    28.500        14.8                8

It seems like a lot of disparity on 10m, but I would have thought that even
if the winding on the 10m toroid were not perfectly spaced, it shoudn't be
that far off?

73
Robin

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