You can get the same airflow by running a larger fan at a lower speed with the benefit being lower audible noise. I have some surplus 4" fans that have rubber feet attached and just sit over the hot portion of the cabinet. I run them at a DC value below their ratings. They don't walk, aren't heard, and substantially lower the peak temps within the radio.
Dennis AE6C On Wed, Nov 30, 2011 at 5:21 PM, Bob Loving <bob.lov...@sbcglobal.net>wrote: > Hi, Paul: > > I purchased a T4-XC with MS-4 speaker and AC-4 on the cheap. The rig, > etc., are in really nice shape and the cabinets of the T4-XC and MS-4 had > been repainted beautifully. > > The T4-XC had an 80-mm square dc fan on the back of the PA cage. Two > screws to mount it at the top and a tie wrap on the left hand side (as > viewed from the back). On inspection, the feed for the fan was the 12.6Vac > filament line with only a 1N4000-series diode in series. The fan runs very > quietly; it is produced by "PPM," (Pony Precision Motor Co. in Taiwan), > model FBA-9, brushless and ball bearing. Any 12Vdc fan would probably work > and you can find the 80-mm fans in abundance from the computer stores. If > you want a higher speed from the fan, add an electrolytic capacitor the > output of the rectifier to increase the average dc voltage. > > 73, > > Bob K9JU > > > > _______________________________________________ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist > >
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