[Amps] drive power

[Michael Tope]

----- Original Message ----- 
From: "Keith Dutson" <kdutson at sbcglobal.net>

> Assuming I now understand the problem of using ALC and too much drive 
> power
> for a given amp, how about just not using ALC in the same situation?  An
> example: use the Icom 775DSP (I have one also) with an Alpha 87A (also 
> have
> one of these and it recommends NO ALC connection).
>
> 73, Keith NM5G
>
> ----------------------------------------------------
> ALC response in most rigs is terrible. It especially gets worse when 
> output
> power is reduced.
>
> My FT1000D doesn't have that problem at all (since it has a real drive
> control) , but my ICOM 706 and 775DSP have terrible leading edge 
> overshoot.

Keith,

I think Tom was referring to the internal ALC loop in the transceiver
rather than the external ALC loop that use the amplifier ALC output
fed back into the transceivers external ALC input. The only way to
effectively disable the internal ALC in most transceivers is to reduce
the drive power to the PA to the point where there is little or no
ALC action. As Tom points out, you can do this on the FT1K-MKV
using the hidden menus. BTW, there needs to be a clear distinction made
between a "drive" control and a "pwr" control. The "pwr" control
just changes the ALC setpoint. Lowering output power with this control
actually increases ALC action. A "Drive" control actually lowers
the RF power input to the transmit string, thereby reducing the amount
of work that the ALC loop has to do to keep the transmitter peak
output power level constant.

73 Mike W4EF......................................