Today I did a few checks on the present fan.
1) I unbolted it from the under-tray and held it in place by hand. There
was no reduction in noise, so I don't think resilient mountings will help.
2) I removed the fan completely and ran it on the bench from an external
PSU. It was a little quieter, but not by much.
3) I tried a small amount of lubrication but that made no difference.
4) One thing that made a surprising difference was the presence or
absence of the "finger guard". In fact anything close to the fan and in
the intake airflow made quite a difference to the noise level. Just
holding a pencil across the intake brought the level up noticeably.
5) Surprisingly there was very little dust around the fan or the heatsinks.
I've managed to locate a new fan that seems to have an equivalent spec -
it should be here in a few days, and hopefully will solve the problem.
I wasn't too impressed by Ten Tec's thermal engineering. The fan is on
the underside of a central chassis plate, and the PA transistor heat
sinks are the other side. There are just a couple of very small holes in
the plate where the air can flow from the fan side through to the
heatsink side!
73,
Steve G3TXQ
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