K2 ALC response

[David Kent-2]

My K2 is serial number 3193.  When I transmit in SSB the ALC meter responds
in various ways.
I get more ALC movement on the lower bands.  There is also more action when
I reduce power.
Is this normal?  If not, does anyone have a remedy?

72,
Dave, K0TCP

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[Don Wilhelm-3]

Dave,

Too much ALC is NOT a good thing!!!  The PSK31 crowd is familiar with the
fact that ALC will worsen the IMD of the signal (which means that ALC
produces distortion through limiting - yes it may be soft limiting, but it
still produces distortion and splatter).

The K2 gain will vary from band to band, so you may see some variation in
the amount of ALC between bands and likely also with changes in power
levels.

If you have more than 1 to 3 ALC bars lighting on voice peaks, you should
reduce your mic gain.  Should you wish to increase the 'talk power' of your
signal, you can increase the setting of SSBC which will increase your
average power through audio compression - IMHO, that is a much better
technique for increasing your average signal power than driving the RF
Section into ALC limiting.

73,
Don W3FPR

> -----Original Message-----
>
> My K2 is serial number 3193.  When I transmit in SSB the ALC
> meter responds
> in various ways.
> I get more ALC movement on the lower bands.  There is also more
> action when
> I reduce power.
> Is this normal?  If not, does anyone have a remedy?
>
> 72,
> Dave, K0TCP
>

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[Ron D'Eau Claire-2]

Dave, K0TCP asked:

My K2 is serial number 3193.  When I transmit in SSB the ALC meter responds
in various ways.
I get more ALC movement on the lower bands.  There is also more action when
I reduce power.
Is this normal?  If not, does anyone have a remedy?

------------------------------------

That's absolutely normal David!

Here's what's happening.

The gain of the transmit circuits is varied according to how much power you
want at the antenna jack. More power, more amplification of the signal from
the source to the output of the final amplifiers. Works the same in CW or
SSB.

The gain of the transmitter amplifier circuits is higher on the lower bands.
On most K2's it peaks at about 40 meters and actually drops slightly on 80
and 160, but where the overall gain of the K2's transmitter circuits is
lowest is up on 10 meters.

So, in 10 meters, the gain is up near maximum for, 10 watts output (or 100
watts if it's a K2/100). On 40 the gain needs to be reduced for the same
output.

The ALC level is a measure of how much the gain of the transmitter is being
reduced to keep the output power at the requested level. So, on bands where
the overall gain is higher, the ALC has to be higher to keep the output at
the right level. You see more bars on those bands.

When you reduce the output power below 10 watts the ALC has to reduce the
gain even further to keep the power at the requested level, regardless of
the band in use. So you'll see more ALC bars appear as you reduce the output
power.

Ron AC7AC

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