Posted by
Ron D'Eau Claire-2 on
Jul 16, 2006; 8:59pm
URL: http://elecraft.85.s1.nabble.com/Weller-WTCPT-illuminated-rocker-switch-tp392187p392189.html
The specified output of the K2 is at least 10 watts CW. The actual output
varies with the band. It is a function of the overall transmitter path gain.
It tends to peak about 40 meters, where most K2's will make 15 watts output,
or very close to it. Up on 10 meters is where the overall gain is lowest and
many K2's just barely make the specified 10 watts output.
Since you're still getting familiar with your K2, here's a couple of things
to remember:
1) The POWER control sets the "requested" power output. The K2 monitors the
actual power output and adjusts the transmitter gain as needed for what
you've requested. The control allows you to "request" any power up to 15
watts, but you can't get that much on all bands.
2) Because the POWER control circuitry is monitoring the power output to
determine how much gain the transmitter circuits should have, the accuracy
of the output power setting depends upon how accurately the K2 measures its
output. A basic QRP K2 uses a simple RF voltmeter to monitor the output. It
is highly-dependent upon an accurate, non-reactive 50-ohm load for good
accuracy. Any significant SWR at the transmitter output will affect it, and
the actual power output. The (KAT2, etc.) ATU's use a bridge circuit that is
a little more accurate, but can still be thrown off by reactive
terminations.
3) If you change the POWER control setting you have to transmit before the
new power level takes effect, since the K2 must sense the output RF to tell
how to adjust the circuits. That means that you may notice that the output
is nearly zero when you hit the first dit or dah after turning the K2 on.
It'll immediately jump up to whatever you have the control set for. The same
is in reverse when you turn the power down. The first time you touch the key
the power will still be up at the old higher level until there's RF for the
circuit to sense.
3) The K2 is rated at 10 watts PEP on SSB, regardless of how much it will
produce. That's because the distortion increases above 10 watts PEP in SSB
mode. CW doesn't need a linear amp, so it's not an issue when you're
pounding brass, but don't exceed 10 watts PEP on SSB on any band.
4) The Bargraph power display is in peak power, so it'll show flickers at
the PEP peaks instead of the average power like most inexpensive external
meters. That cause confusion sometimes when the opr notices that his
external meter is wiggling around at 3 or 4 watts while his K2 shows 10 watt
peaks on SSB. That's normal. The external meter is showing the average
output, not the peak.
Welcome to the K2-club John! I built mine in 2000. It's a FB rig.
Ron AC7AC
-----Original Message-----
Hi all
I have been having great fun with the K2 but I am wondering what the output
should be?
10W or 15W?
The Po control seems to indicate 15W should be possible.
The PA alignment seems OK, or at least as per the manual, Po/current seems
to match at the levels stated.
But occasionally the built in detector seems to read a little higher than
the Po is set to and the full scale setting of 15 only seems to yield 11w or
so.
As this is the only one I have built so far I am curious.
Any guidance appreciated.
John
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