[Top] [All Lists]

Re: [Amps] Current draw fan Alpha 77

Subject: Re: [Amps] Current draw fan Alpha 77
From: Martin Sole <>
Date: Tue, 24 Oct 2017 07:53:58 +0300
List-post: <>
Hello Gary,

My 77D(x) has a rheostat in the blower supply. I'm not sure if that was the same for all. Since mine is an early model it also has a thermostat switch mounted on the exhaust plenum that shorts out this resistor. I believe that was later deleted. I have the blower set quiet slow with the rheostat but the air out the back never seems to get too hot and the thermostat has never switched to high speed but then I don't tend to use it for high duty cycle modes.

My blower is quite noisy, definitely worn bearings and I plan to replace them in the next few weeks. If that proves successful maybe I can run the blower a bit harder without needing ear defenders.

Whilst some might argue the original 77 transformer was a bit weedy and the tank circuit somewhat undersized in some situations (2 tubes on 160m) the blower by comparison seems almost excessive in the 77, almost able to achieve that desired state of being able to lift the tube from its socket :) This on a 50Hz supply where a lot of blowers are distinctly under sized.

73, Martin, HS0ZED

On 23/10/2017 18:35, Gary Smith wrote:
Not sure why my message didn't send
properly but I'd sent:

Got it. Thanks for the direct replies.

I am finally getting around to adding a
thermostat to the amp to allow slower fan
rotation at idle and full rotation when
transmitting. The blower on this thing is
a beast.


Amps mailing list

Amps mailing list

<Prev in Thread] Current Thread [Next in Thread>