K3 Mic Gain vs ALC

[Benny Aumala]

You are not alone....

Not only SSB. I have overshoot on CW.

Adjust your power to e.g. to 22W and wait a while.
With the first mark, the power shoot high
but comes at once down to preset value of 22W.
Instantly following mark starts OK.
You have to wait for about 15 seconds to see it fully again.

It is difficult to find without a fast meter or screen,
e.g. oscilloscope or peak reading meter (LP-100A).

With barefoot K3 this is OK, but feeding a high-gain
amplifier might be fatal.

Benny                   OH9NB

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[P.B. Christensen]

> Not only SSB. I have overshoot on CW.

This problem appears to be rig-specific.  I just duplicated his test using
three wattmeters in series, together with a Bird 4273 RF sample.  The sample
feeds a Tektronix SC504 oscilloscope.  My wattmeters are the Alpha 4510,
LP-100, and Array PowerMaster.  With the K3 set to 22 watts from the menu,
keyer to 30 WPM, I then sent a single "dit" on 40M CW into a 50-ohm Bird
TermaLine load.

Observation:  I waited 30 seconds for the ALC to stabilize between each
successive "dit."  All three wattmeters read between 22-23 watts in peak
mode.  The oscilloscope showed no overshoot whatsoever.  I have no mic to
plug into the K3 at the moment, so no SSB overshoot testing was performed.

Paul, W9AC
 

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[Ken Wagner K3IU]

I have to echo what Paul says. This must be rig specific.

I don't have the elegant equipment he describes, but taking the output
of the K3 to a dummy load (50.1 + j0) and looking at it on an old HP
1740A scope, I see no overshoot on either CW or on SSB using an Elecraft
Proset plugged into the rear connection; CONFIG:r:L BIAS, AF Gain set
for ALC indication of 4-5, CMP settings between zero & 30. At any power
setting I select I get the same result.In SSB, a brief whistle produces
the commanded power display on the scope with no overshoot.

73,
Ken K3IU

Paul Christensen wrote:

>> Not only SSB. I have overshoot on CW.
>
> This problem appears to be rig-specific.  I just duplicated his test
> using three wattmeters in series, together with a Bird 4273 RF
> sample.  The sample feeds a Tektronix SC504 oscilloscope.  My
> wattmeters are the Alpha 4510, LP-100, and Array PowerMaster.  With
> the K3 set to 22 watts from the menu, keyer to 30 WPM, I then sent a
> single "dit" on 40M CW into a 50-ohm Bird TermaLine load.
>
> Observation:  I waited 30 seconds for the ALC to stabilize between
> each successive "dit."  All three wattmeters read between 22-23 watts
> in peak mode.  The oscilloscope showed no overshoot whatsoever.  I
> have no mic to plug into the K3 at the moment, so no SSB overshoot
> testing was performed.
>
> Paul, W9AC
>
>
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>

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[Julian, G4ILO]

Ken K3IU wrote

I have to echo what Paul says. This must be rig specific.

This is just a shot in the dark - in fact I decided against posting this when I first saw the thread because it's probably wrong - but could it be *mic* specific? Some mics disconnect the element when the PTT is released. It's possible a "click" could occur when the switch is connected that is causing this spike.

[Ken Wagner K3IU]

G'morning:
That's a good thought. I used both VOX and a foot-switch PTT and saw
nothing unusual using either method.
73,
Ken K3IU
K3 #202

G4ILO wrote:

> Ken K3IU wrote:
>  
>> I have to echo what Paul says. This must be rig specific.
>>
>>    
> This is just a shot in the dark - in fact I decided against posting this
> when I first saw the thread because it's probably wrong - but could it be
> *mic* specific? Some mics disconnect the element when the PTT is released.
> It's possible a "click" could occur when the switch is connected that is
> causing this spike.
>
> -----
> Julian, G4ILO  K3 s/n: 222 K2 s/n: 392
> G4ILO's Shack: www.g4ilo.com
> Zerobeat Ham Forums: www.zerobeat.net/smf
>  

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[Don Ehrlich]

A friend and neighbor (KC7ORH) asked me to see if I could find a used KX1
for him.  He is not interested in building up a kit and it would be nice if
he could save a buck or two by buying a used radio.  I'm not sure what
options he would be interested in but if you have a good KX1 that does not
get used anymore then let me know and/or reply directly to Jim at
[hidden email]  and tell me (or him) what you have.

Don K7FJ


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