I don't know offhand what the L4 uses as its cooling blower, but my SB-220
has a large fan (rather than a squirrel-cage blower) that is mounted in the
back of the cabinet and blows directly on the tubes. What I did was to
place a small "muffin fan" - like the ones in computer power supplies -
directly above the tubes on the upper cabinet. It operates as you suggest,
sucking air from the area around the tubes, and I have found it definitely
helps keep the tubes cool.
73, Pete N4ZR
At 02:32 AM 2/14/2008, DEHAYS Dominique wrote:
>sorry , same message but with the rigth message title
>
>
>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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