[Elecraft] ALC and External Power Amplifiers (K2)

[Harry Yingst]

Actually, I have heard and done it both ways.

The main reason I like ALC is to protect me from my own stupidity.

I have in the past not ran ALC and thrown 100 watts into an amp that
was not setup for it lucky that one was a pair of 3-500ZG tubes and it
could take it.

The 3CX800A7 I run now in my commander amp would have been ruined, and
at about $450.00 each there a little stiff to replace.




--- VR2BrettGraham <vr2bg@harts.org.hk> wrote:
> K2VCO replied to AB2PN's post:
> 
> >There isn't one, but it would be useful.  Although activation of ALC
> on
> >a regular basis is not a good idea (since it has a finite attack
> time,
> >it can't prevent driving an amplifier into nonlinearity, at least
> for
> >short periods), it can function as a safety feature.  For example
> I've
> >just installed an Alpha 86.  It produces 1 KW output with about 35
> watts
> >of drive (I haven't dared to run the full 1500 watts for fear of
> >damaging antenna components, etc.).  I can only shudder to think
> about
> >what might happen if I forgot to turn down the power control on my
> K2
> >and hit it with 100 watts!
> 
> My Ten-Tec 420E & a recently acquired ACOM 1k have on a number of
> occasions indicated they did not appreciate what appeared to be far
> greater
> drive (based on number of light bulbs on K2/100: all) than I would
> expect
> based on position of the POWER control (anti-clockwise 50% or
> greater) for
> short instances.
> 
> I normally observe variations in output level to be of
> lower-to-higher power,
> such as for the first few key-down elements after a band change (good
> idea,
> Elecraft!).
> 
> Wasn't there a post by somebody recently that suggested the power
> level
> steps when the KPA100 kicks in might be better if it weren't so
> granular,
> followed by a reply from Elecraft that something might be done about
> it at
> some point?
> 
> Thankfully, my 8877 amp has so many problems I can't use it, but I'd
> be a
> little concerned with the overshoot mentioned above (perhaps a fault
> with my
> particular K2/100?) or dithering of the drive that I often see due to
> the
> granularity should one operate such a sensitive tube close to its
> limits.
> 
> That amp (DTR-2000) was probably the worst 8877 implementation, but
> thankfully most everything else has reasonable protection.
> 
> 73, VR2BrettGraham
> 
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=====
Harry - AB2PN

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