[Premium-Rx] Cubic 3280 Fan Noise

[Bob Betts]

Dan, glad you finally found what you wanted. My 3250 had a very noisy fan as well. One problem is that it is over a slotted opening which creates tremendous air flow turbulence (siren effect). A quick improvement is to rear mount the fan and position it to blow cool into the chassis, not suck out hot air. Cool air handling is always more efficient. Secondly, try adding 5-watt ceramic resistors in series with the power to the fan. I don't recall the values I tried, but kind of think it was around 25 ohms. I did some testing with the fan disconnected and the temperature rise at the power supply was significant, so forced cooling is important. But it is really over done on these radios, and I might say, poorly implemented. In defense of the engineers, maybe the noise level wasn't important for the intended applications.On the plus side, these receivers are really super performers. I have spent many hours comparing them to the likes of WJ-8718, RA6790, ITT/Mackay, etc. Just be careful with the vacuum fluorescent display. They are not available anywhere and the only fix is to find another used Cubic and scavenge its display...as I had to do. I have a youtube of mine and apologize for the lousy camera work ahead of time. Sorry, but I wasn't sharp enough to film the fan mods. If the 3250 is any indication, I think you'll really enjoy the 3280.Good signals to all,Bob, N1KPR
https://www.youtube.com/watch?v=6UD3PcLVYSg