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K3 TX power overshoot

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John Simmons

K3 TX power overshoot

I have a 6xxx K3 (not S). The output of the radio is monitored by an
LP100A wattmeter set to peak reading. The K3 drives an AL80B. I have
just done a TX power calibration. With the K3 power output set to 60
watts and running SSB I will see about 64 watts output but occasionally
see 74 watts peak on the LP100A. I am about to change to a solid state
amp and am concerned that I will damage the solid state amp by overdriving.

Is this normal behavior? If not, anything I can check, change or align?

73,
-John NI0K
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Bob McGraw - K4TAX

Re: K3 TX power overshoot

I occasionally see a wee bit of overshoot as seen on my KPA500. I'm
driving it from my K3S at about 20 watts for about 400 watts out on
SSB. Occasionally I'll see a 450 or 500 watt indication on the LED
bargraph. The KPA500 doesn't seem to mind.

If I set the drive power to 20 watts CW mode, I never see any overshoot.

There is a TXG VCE menu item in the CONFIG menu. Check the value of
this. It balances voice transmit peak power in relation to CW peak
power. See page 67 of the manual.

73

Bob, K4TAX

On 1/11/2019 3:21 PM, John Simmons wrote:

> I have a 6xxx K3 (not S). The output of the radio is monitored by an
> LP100A wattmeter set to peak reading. The K3 drives an AL80B. I have
> just done a TX power calibration. With the K3 power output set to 60
> watts and running SSB I will see about 64 watts output but
> occasionally see 74 watts peak on the LP100A. I am about to change to
> a solid state amp and am concerned that I will damage the solid state
> amp by overdriving.
>
> Is this normal behavior? If not, anything I can check, change or align?
>
> 73,
> -John NI0K
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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Eric Norris-2

Re: K3 TX power overshoot

In reply to this post by John Simmons

I see TX power overshoot when there is too much audio drive. The 5th bar
should be flashing not solid on the ALC meter. Also, do a TX GAIN
calibration procedure from the K3 Utility.

My KPA500 has endured some massive peak power overshoots without
destruction (1200w) before I readjusted things. I also use an LP-100, and
it seems to have an extremely sensitive peak mode.

73 Eric WD6DBM

On Fri, Jan 11, 2019, 1:21 PM John Simmons <[hidden email]
wrote: