[Amps] Current draw fan Alpha 77

[Martin Sole]

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.
>
>
> 73,
>
>
> Gary
> KA1J
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