Interesting about the AL82. I have an AL-80B, and have owned in the past a
variety of 3-500Z amps from SB-220's to Henry 2K's to Drake L4B's, and one
old Swan Mark II, and oh, what was that-?, I think a product made by
Raytrack, whoever they were...and in general, the 3-500Zs always worked fine
and I never had any early life failures in any of them.
The AL80B is quiet, using one 120mm Pabst (German) ball bearing axial fan
and moving quite a volume of air. The exhaust is not restricted much in the
AL80B at all, and any type of paper, including heavy cardboard, placed
across the air inlet gets sucked right against the cabinet immediately and
stays there; the thing's kind of a vacuum cleaner, but that's not a bad
thing unless you have a lot of metal filings around.
An informal "smoke test" on an AL80B (performed clandestinely when the XYL
was away, since I stopped smoking and now she can tell in one second if a
cigarette is lit anywhere near the house) reveals the smoke sucked through
the amp and blown out in less than one second, and the smoke flies out with
great velocity. Impressive cooling for a single 120mm muffin fan. No idea
why they would muck it up in the 2-hole version.
The Henry amps, using a blower and chimneys, moved a lot of air. My last
Henry, a 3K Premier with a 3CX1200A7, had a 220V blower that must have been
made by Pratt-Whitney, because it sounded just like a DC-9 taking off.
Which is one of the reasons I sold the amp.
73! WB2WIK/6
"Each success only buys an admission ticket to a more difficult problem." --
Henry Kissinger
> -----Original Message-----
> From: Steven Moore [SMTP:wd0ct@networksplus.net]
> Sent: Friday, September 28, 2001 2:36 PM
> To: Steve Katz
> Subject: Re: 3-500z cooling
>
> Hi Steve,
>
> Yeah, I had those same questions about the blowers and chimneys--they just
> seem like the "right and common sense" way to do it. I think that a tube
> run
> at max dissp might still be better off cooled with chimneys etc. But just
> search the amps reflector archives on cooling, chimneys, sb-220 etc. and
> you
> will see a lot of discussion about it. I even asked once if anyone had
> done
> the smoke flow test on a sb-220. I didn't really get an answer, but the
> explanation of the Eimac labeling {ink on the tube] never changing color
> on
> an Eimac 3-500z in a sb-220 [regardless of where the ink was in the
> airstream] finally convinced me all was well without chimneys etc.
>
> By the way, the wimpy blower on a Drake L4-B moves hardly any air out of
> the
> chimneys that you can feel with your hand. On the other hand, the ball
> bearing blower [4 selectable speeds] in an Ameritron AL-82 [pair 3-500z]
> is
> a noisy beast plus the venting on the case is too small for the exhaust
> causing the case to get very hot. The explanation given by Ameritron to my
> buddy that owned it was the venting was made too small to decrease noise.
> He
> made a new top for it with increased venting but the noisy beast [even
> with
> the fan set on number 2 speed] forced him to sell it to keep his sanity.
>
> 73
> Steve wd0ct
> ----- Original Message -----
> From: "Steve Katz" <stevek@jmr.com>
> To: "'Steven Moore'" <wd0ct@networksplus.net>; <amps@contesting.com>
> Sent: Friday, September 28, 2001 4:03 PM
> Subject: RE: 3-500z cooling
>
>
> >
> >
> > > Hi Steve,
> > >
> > > This has been tossed around on here numerous times. You do need some
> air
> > > movement around the seals. Muffin or similar fans [sb-220] work just
> fine.
> > > My Amp Supply LK-500ZC has a 5 inch muffin fan, the output of which
> partly
> > > blows below the raised [and open on the other end] tube socket
> platform
> > > thereby cooling the tube pins/seals.
> > [Steve Katz] I realize that, although I have not made any
> > measurements to confirm how effective this is. I'm questioning why
> Henry,
> > Drake and others used centrifugal blowers and glass chimneys, at
> obviously
> > increased cost and complexity, when these things are apparently not
> > required. And my very old Eimac data sheets on a variety of power grid
> > (glass) tubes recommends use with their glass chimneys. Was that just
> to
> > sell expensive glass chimneys?
> > >
> > > As for cooling the tube glass envelopes, the high volume low pressure
> air
> > > from these type fans wraps around the tube envelope and cools t very
> well.
> > [Steve Katz] Seems to.
> > >
> > > 73
> > > Steve wd0ct
> >
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