The L4 blower is sufficient to keep the tube seal temperates well within
spec during normal CW/SSB use. For RTTY and digital use run it at about
700-800W output by reducing the input drive.
After 45 years the blower may need a cleaning and lubrication for full
efficiency.
Carl
KM1H
----- Original Message -----
From: "DEHAYS Dominique" <dominique.dehays@enac.fr>
To: <Amps@contesting.com>
Sent: Thursday, February 14, 2008 2:25 AM
Subject: Re: [Amps] Looking for eimac 3-500Z
> Hello ,
>
> I recently got a second hand Drake L4 amplifier. I am normaly not an HF
> op , but sometimes , I have to use HF ( for VHF nets) , so the L4 is a
> nice addition when HF conditions are not good. I am rather used to VHF
> amps , where the blower is quite powerfull , and the tubes are well
> cooled. On the L4 , there is only a quite weak air stream , provided by a
> small , low speed squirel cage blower. One can easily feel the warm smell
> in the shack after a 1 minute transmission whne going back in RX , and I
> dont like this.... Anybody has ever improved the L4 cooling? I'm thinking
> I could add two blowers , each one above one tube to " suck" air trougth
> the tubes chimneys. What do you think about this?
>
> 73
> Dom/F6DRO
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