> Anyone have a brand they recomend for a no noise, reliable fan. > I didnt know whether to go with brushless,ball bearing,AC, or DC etc. > Also should the power leads be sheilded and have a separate supply if DC.. > Any filters recomended also.. > This is my first repeater and am now into the cooling part of the project.
By far the best approach is "no fan at all", that is, use passive cooling and just a big enough cooling block that it simply doesn't heat up enough to be an issue. You should be able to key-up the TX for a few days and not even have to worry about the temperature, that's what I do even before considering putting anything on a building or a hill. Repeatersites are seldom clean and fans just clog, They push dirt at places you really don't want any, and if they fail you'll be none the wiser. You really are better off without a fan at all. Consider fans with a "tacho-output". This will pulse on every turn and you can fix your controller to warn if the fan should be running (and the pulses are missing - i.e. the fan isn't running). Brand-wise I found fans by EBM-PABST a lot more reliable than the typical Asian counterpart. Go for ball-bearing fans, not sleeve-bearing, they typically only last 20000 hours. PABST does publish realiability numbers on their datasheets - I suggest you do the math first. Oh, plan to visit the repeater site every year to change fans? I would think not, some of my repeaters I don't even have access to, requiring coordination et all. Apart from temperature, *temperature-cycling*, i.e. heating up during a log of activity and cooling down, is your big killer. As things don't grow and schrink the same way on temp rise, temp changes cause stress. For one, if you use RF power modules, make sure the leads are not tight, but use a little bow so the leads can bend (instead of stretch) with temp changes. Enough? 73, Geert Jan PE1HZG
