EBM is the only choice for my projects...73 all...K7RDX..
On 1/27/22, jim.thom jim.thom@telus.net <jim.thom@telus.net> wrote:
> From: Byron Tatum <bjtatum1@att.net>
> To: Amps Group <amps@contesting.com>
> Subject: [Amps] Centrifugal Blowers
> Message-ID: <2012770418.1476844.1643242299355@mail.yahoo.com>
> Content-Type: text/plain; charset=UTF-8
>
> Hello-? ?Anyone in our group have knowledge of replacing the motor on a
> centrifugal cooling blower? I have been rebuilding a few RF decks made in
> the 1970's by Scientific Radio for the SR-416A transmitter. These RF decks
> are a copy of the Eimac W6PO 144 Mhz design using 8877 tube. They use a
> Kooltronics blower with 5" wheel and square outlet with mounting hole
> centers 2-5/8" apart in a square pattern. I have bearing noise and
> vibration in a few of my motors. The motors are sealed bearing Kooltronic
> #7162-082 type U62, 115 VAC @ 1.55 amp, using 4 ufd capacitor. 2850 RPM at
> 50 Hz, 3400 RPM at 60 Hz.? ? After looking at prices of replacement
> blowers/motors I was shocked. Can I replace the bearings in these motors?
> Or just buy new motors somewhere? I really do not need the performance of
> these blowers, the transmitters were running at 1 KW 24/7 and I am just
> doing SSB/CW. Sure could stand to reduce the blower noise some.?
> ?Thanks,Byron W5FH?
>
> ## Phone / contact Kooltronics and ask them if the bearings can be
> replaced..and if they stock them. I believe a special bearing tool is
> required to remove / install them. They might also be able to replace em
> for you. They are nice folks to deal with on the phone. German
> EBM-Papst blowers, like what's used on the Ameritron amps, indeed, have
> replaceable bearings..as does the old Rotron CX-33, used on many FM
> broadcast stations. The CX-33 is still rebuildable, even though out of
> production for years.
>
> I had several CX-33 blowers, with the cap start, these were 230 vac single
> phase types..and tried them on my small 0-240 vac @ 5 amp variac. Worked
> superb. I could dial it up anywhere from a crawl to full bore..and
> everything in between. Then ran em for extended hours..at intermediate
> speeds, with no degradation, or heating etc. A metal finned resistor can
> also be used to slow em down.
>
> Dayton blowers have a huge catalog online. They revamped their blower line
> up a few years ago, and the new versions all have ball bearings, no sleeve
> bearings..and the new style / design motors only draw 1/2 as much current.
> Available in flanged or unflanged. Detailed dimensions, including flanges
> etc, etc, online.
>
> I bought 4 of the ebm papst blowers..to replace the oem drake blowers, in
> my 4 x L4B's. These are the same ones used in the ameritron AL-1500 8877
> amp. On that ameritron amp, they offer 3 x speeds, by changing taps. IE:
> 3 x different voltages fed to the 120 vac blower. Max speed, and 2 x
> slower speeds. Max speed used for RTTY / FM. Lower 2 are for ssb / cw
> etc.
>
> I bought mine from Digikey. Mouser also sells em. The Baffling part is...
> the 230 vac version is one helluva lot cheaper than the 115 vac version,
> like almost 1/2 price, go figure. I never run the drake amps on 115 vac, so
> it's a moot point.
>
> I have seen too many blowers getting tossed... simply from a bad bearing.
> A freq drive will also work to slow em down. Chinese variable freq drives
> are cheap..and actually work good.
>
> I also use ebm papst deluxe EC ( electronic commutator) 115 vac
> version blowers. With a 10 k pot wired in, the speed can be changed from
> 1/2 rpm, to max rpm. These are 70 cfm @ 1.2" high pressure types, used
> on 3CX-3000A7 tubes. It also has a tachometer output, and bearings are
> field replaceable. Beauty of the EC motors is... they draw a miniscule
> amount of current, like just .4 amp on high speed...and only .12 amp on low
> speed. Don't even run luke warm.
>
> Jim VE7RF
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