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Re: [Amps] ALS-600 Blowing Out Finals

To: "'chris bauer'" <>, <>
Subject: Re: [Amps] ALS-600 Blowing Out Finals
From: "Joe Subich, W4TV" <>
Date: Sat, 29 Mar 2008 10:01:36 -0400
List-post: <">>
> Using 60 watts drive Icom756-pro any Ideas how to get 
> Longer life out of the MRF-150's

Many of the "modern" transceivers have excess IF gain and 
use the ALC circuit for power control.  Due to time constant 
issues (the manufacturer wants the radio to reach full power 
instantly) these transceivers can have spikes of 150 to 200 
watts on the first transmission (first CW character or first 
syllable of speech).    

If your Pro is hitting the ALS-600 with just a 125 watt 
spike, that's more than 3dB overdrive and could cause a 
problem for the MRF-150s.  Since your ALS-600 requires only 
60 watts of drive, I would be looking to install a 2 dB 
pad between the T/R relay and the input transformer in the 
amplifier.  That will allow you to run the transceiver at 
normal power levels and minimize any spike.   

You could also have the Pro checked to see if there is an 
IF gain adjustment and reduce the IF Gain to the minimum 
level necessary to produce the specified output power. 


   ... Joe, W4TV 

> -----Original Message-----
> From: 
> [] On Behalf Of chris bauer
> Sent: Friday, March 28, 2008 10:25 PM
> To:
> Subject: [Amps] ALS-600 Blowing Out Finals
>   I Bought My ALS-600 2 years ago Just before the one year 
> warranty was up the RF Section went out. Sent to Ameritron Repaired.  
> One Year Later Same Problem ...This Time Out of warranty..... I Use  
> the amp  only to work dx. I am Not Happy I know this Repair 
> Costs will  
> be 2-300.00 I switched to the ALS-600 Due to a Pacemaker that 
> i had to  
> Have. Really Miss my old Reliable Tube AMP for 1200.00 Bucks I  
> expected Better.Using 60 watts drive Icom756-pro
> any Ideas how to get Longer life out of the MRF-150's de Chris/N8EWX 
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