Hi Wendell -
The noise you are hearing is probably the nylon/plasting fan hitting the
back of the amp. What happens is that the fan blade loosens on the shaft.
Reseat the fan on the shaft and then find a way to keep it from moving
again. Best bet is to check it every time you clean the amp.
The switch (a small low current switch) can be mounted where the Heath
emblem is located. Just use it to switch the B+ on the relay. Makes a good
standby switch.
73,
Jay
At 12:38 PM 5/21/97 -0500, you wrote:
>Question 1: The fan in my SB-220 starts making noise after several minutes
>of operation and the temperature of the exhaust air has increased
>significantly. Quiet when it cools back off. Can they be lubricated or is
>there any source for a good quality fan. I built mine in 1980 and this is
>the first problem (still has both original tubes) so I am satisfied with
>the performance.
>
>Question 2: When I work on the fan, I would like to add a switch to allow
>standby operation. Is there a mod that changes out the rocker switches for
>a three position switch or any other good ideas. I also want to add a
>circuit to control the relay from a low level supply as I DO NOT like
>bringing the relay return out to a solid state transceiver. I would prefer
>to build the circuit rather than use one of the commercial boards for that
>purpose, but I guess an inexpensive one would work as well.
>
>Wendell Wyly W5FL w5fl@flash.net
>
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