: FT101 Fans: Optimum choice?*

Hello, all.
Chris here, near Portsmouth.
My standard 101fan would take 10 minutes to inflate a dustbin liner, OK it
wasn't noisy, but then it wasn't that much of a fan either... My objective was
to generate sufficient airflow that \i could feel confident about blocking
up all of the holes in the top cover, to keep crap out. Many fans were tried.
The immediate problem is that theh pitch circle of the Yaesu mounting holes
is smaller than the usual 80mm fan. Many of the latter couldn't be modified
to fit because of the shape of the venturi casting. Of those that could be
fitted, a common problem was magnetostrictive resonance of the steel FT101
chassis, causing an unacceptable level of hum. There was no problem with
airflow with any fan tried. Best way ahead: use Papst model 8978, a ballbearing
fan intended to be run from 240V. Run another wire from the mains tfmr to tone of the spare pins on the fan socket, to give 115Vac rather than the 100Vac
available already. Run the fan from the 115V and there you will have a good
installation, far more efficient than the original design, but no noisier. 
The venturi casting DOES need nodification, but this is possible with ordinary
hand tools given care. 73 de Chris, G8JFJ @ GB7HJP