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Re: [Amps] Fw: help

To: A Lawrence Fibich <>
Subject: Re: [Amps] Fw: help
From: MU 4CX250B <>
Date: Sat, 22 Oct 2022 11:33:54 -0700
List-post: <>
Hi Larry,
ALC/AGC circuitry in linear amplifiers was primarily used in the days
of vacuum tube, transceivers, which did not have a power output
control. With your station, there’s no need to use the ALC.   Just
don’t connect the cables and you’ll be fine. Your ICOM transceiver has
a power output control, so just turn the power down so you don’t
overdrive the L4B or L7.
Jim w8zr
Sent from my iPhone

> On Oct 22, 2022, at 11:58 AM, A Lawrence Fibich <> wrote:
>  Guess I am not sure how to post a listing -- thanks..
> Larry FW6EF
>   ----- Forwarded Message ----- From: A Lawrence Fibich 
> <>To: 
> <>; 
> <>Sent: Friday, October 21, 2022 at 11:32:03 PM 
> PDTSubject: help
>  Subject: Questions: Connecting a Drake Amplifier
> Hit a roadblock I am not understanding. I wanted to connect a Drake L-4 
> Amplifier (also have a Drake L-7 - same problem). Looking at the input the 
> unit/s want - they want AGC input - I am familiar that ALL other Amplifiers I 
> have used accept/require ALC input.  I am trying to drive either of these 
> units with a ICOM IC -756 - it only outputs an ALC.  Of course the 
> definitions of AGC and ALC is not the same - or about the same functions.
> Then also - beyond my understanding clearly caution in the manual ... 
> "WARNING: Set the Transceiver output power and linear amplifier ALC output 
> level referring to the linear amplifier instruction manual.  The ALC input 
> level must be in the range 0 V to -4V and the transceiver does not accept 
> positive voltage.  Non-matching ALC and RF power settings could cause a fire 
> or ruin the linear amplifier."QUESTION: 1. How do I connect the ICOM to the 
> Drake Amp? - ? what if not connecting anything to the AGC on the Amp?2. How 
> could a 'non-matching ALC and RF power setting cause a fire? ?over heating 
> the Amp?
> Thanks for any assistance73W6EFLarry FibichSacramento, CA area
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