[Elecraft] ALC: issues raised almost 2 month ago + answer from Elecraft

[Vic K2VCO]

Jerry Flanders wrote:

> Not so - Wayne's comments seem directed at those who might want to use 
> ALC as if it were a substitute for the mike gain control.
> 
> It worries me when I see the discussion wander away from amplifier 
> safety in an antenna catastrophe situation, which is my main concern. I 
> once blew up the output circuit of an AL1200 due to an intermittent in 
> an antenna coax while running full power on RTTY.

Although ALC can be used for amplifier protection, it's the worst way to 
do it, because it depends on things not in the control of the amp 
designer. A well-designed amplifier should be able to protect *itself* 
from high reflected power, overdrive, etc. by taking itself offline.

> "The ALC cable must be connected between
> the transceiver and VL-1000 to
> prevent overdrive of the amplifier, and especially
> to facilitate the proper operation of the
> protection circuitry if sudden antenna system
> problems should cause the SWR to rise to dangerous
> levels."

This is exactly now NOT to do it. How do you know you have the system 
adjusted properly? The *only* way you could depend on this is with an 
amplifier and transceiver of the same manufacture, specifically designed 
to work together. Suppose you were driving it with an ICOM transceiver 
and it blew up? Would you complain to Yaesu because the amp failed to 
raise ALC quickly enough or to ICOM because the transceiver didn't 
respond in time?

> I, and perhaps other Solid State amp users, would prefer a definite 
> calendar commitment, if that is possible. If not possible, please state 
> so. I would hope for a working, properly engineered negative-going ALC 
> fix within a few months.

How will you know it's 'properly engineered'? They are not going to 
guarantee that your brand-x amplifier won't blow up!

Of course, you do have the option of waiting for it to become available 
before purchasing a K3. I wrote Bill Gates and demanded a calendar 
commitment for Vista to support 'standard' HLP files. He didn't answer!

I still don't know how you would verify that it actually provides the 
protection that you want.
-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco