Re: TT RE: TT RE: [TenTec] Ten Tec amps and ALC

[Ken Brown <ken.d.brown@verizon.net>]

Tommy wrote:

> Your correct Al.
>
> My point is that just because an amp has a nice LED that's turned on by
> external-ALC, one should not get too comfortable that their amplifier is
> 'safe' from a poorly designed RF output circuit in the driving transceiver.
> Since it is not an instant death threat to the amplifiers tubes, most folks
> will ignore it.
>  
My understanding of ALC in amplifiers (and overdrive indicator LEDs) is 
that they are activated by RF drive to the amplifier. I guess you might 
call that an "external" source. However due to the way you have stated 
this, I sense  some confusion as to which way the ALC signal is going.  
The ALC signal is generated in the amplifier and is sent to the exciter. 
There is no signal coming from the exciter on the ALC line that turns on 
an ALC or overdrive indicator on the amplifier. It is only the RF input 
(drive from the exciter) that does this. ALC signals in RF PAs are 
derived in various ways, and PA tuning can have big effects on the ALC 
signal that is produced. So it would be incorrect for me to say that it 
is ONLY dependant on RF drive.
The ALC line on an RF PA is an OUTPUT. The ALC line on an exciter is an 
INPUT.
DE N6KB