[Elecraft] K2 # 2448 queries

[Ron D' Eau Claire]

>
> -I can't record the CW messages, when I hold down the 'message'
> button for
> record, the rig beeps and returns to normal mode. Am I doing
> anything wrong?
> (firmware is version 2 and using straight key)

You cannot load the CW memories using a straight key. It will only record
keyer actions input with paddles. Leo Starrenburg, PA5LS, wrote a small
program for a PC that will allow you to program the CW memories using your
PC. I didn't keep a record of the URL where you can download it. If you are
interested and no one offers it right now, I'd suggest a new message asking
and I'm sure Leo or one of several others will give it to you.


> -I have noticed that with the audio gain all the way down, strong
> stations
> still come through, which are just audible to be annoying whilst the
> operator is on another rig. Would it be possible to program in some mute
> function? or is it a case of turning down the RF gain as well?

The volume control in the K2 does not work well on a number of K2's. In K2's
that have a somewhat 'hotter' audio amplifier section, the audio cannot be
turned all the way down. Also, you will notice that you normally work with
the audio gain very near the minimum level, especially when using
headphones. And a lot of operators discovered that the audio gain control
became 'noisy' in a short period of time.

Here's the problem. As designed, the audio gain is just a 'shunt' that tries
to "short out" the audio going into the audio amplifier. Very small
differences in the minimum resistance of the audio gain control cause audio
to leak through. Also, control becomes 'noisy' quickly, as it was not
designed to have a very consistent minimum resistance when turned all the
way 'down'.

There is a "fix" that rewires the audio gain to work more like a normal gain
control. You can access the modification on the Elecraft web site at
http://www.elecraft.com and then click on Builder Resources. On the page
that opens look for "K2 AF Pot Application Note". It is a very worthwhile
modification to make. The "action" of the gain control well be greatly
improved. It will have a control characteristic much more like the volume
control on other equipment. Also, you will be able to turn the audio all the
way 'off' when it is at the minimum gain position.

>
> -I understand that the AGC can be set to 'fast' or 'slow', does it matter
> which, what is the difference? (I was told that 'slow' was for SSB and
> 'fast' for CW)

Someone told you "wrong" <G>. The Fast and Slow settings determine how long
the AGC waits AFTER the signal 'disappears' before the gain is returned to
maximum. Normally, the AGC adjusts the gain of the receiver to produce a
fairly constant audio output regardless of changes in the strength of the
received signal. For SSB or AM phone, you want it to react fairly quickly so
that it will turn down the gain quickly when a strong signal appears, and
then it will quickly bring up the gain of the receiver if the signal fades.
For that use, the "FAST" setting is usually best.

If the AGC follows the signal too quickly in CW, it will "pump" the gain up
and down between dots and dashes, making the "background" noise as loud as
the signal. So, for CW, a "Slow" setting is provided that will cause the AGC
to wait a brief period before it brings the gain up at the end of each dot
or dash. That will prevent the "pumping" effect on most signals, while still
allowing the AGC to follow slower changes in the signal levels due to QSB.
Very s-l-o-w CW might still produce pumping, even in SLOW setting.

Many ops, including this OT, do not like to use AGC for CW at all. Try
listening to CW with the audio gain near full up and turning down the RF
gain control to adjust the volume, and you will hear why we avoid AGC in CW.

For most normal CW reception the signals will stand out much more clearly
and cleaner-sounding above the background noise. That's because the AGC is
no longer trying to keep the same audio level in your phones or speaker
regardless of whether it's the signal you want to hear or the background
noise during a pause. You can turn the AGC OFF, but just reducing the RF
gain control will pretty effectively 'disable' the AGC.

If your read the older texts for proper receiver operation back when CW was
the dominant mode in Ham communications, you will see that nearly everyone
ran the audio gain up pretty high - set just below the level where the audio
amplifier's background noise became noticeable - and used only the r-f gain
control to adjust the volume.

The only thing having AGC working in CW does for you is to allow you to use
the S-meter, and the S-Meter is arguably one of the most useless inventions
in all of Hamdom anyway. (But that's just this OT's opinion, Hi!)

Ron AC7AC
K2 # 1289