On 2/21/2013 7:02 AM, Jim Thomson wrote:
Date: Tue, 19 Feb 2013 16:36:40 -0500
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
To: amps@contesting.com
Subject: Re: [Amps] Peter Dahl Transformers
## Nothing wrong with running a small, low speed fan in any HV supply. The temp
inside the
cab should be the same as the room temp. It?s worth it to keep the plate xfmr,
hv electrolytics, bleeders,
eq resistors, and any glitch resistor cool.
I use filters that are like a very fine screen. They can be pulled out
and cleaned with an air gub, but usually a vacuum is more than sufficient.
They run and run and run in the shop. 6 months usually shows very
little accumulation, BUT I run a whole shop filter usually let it run
all day if I do any welding, cutting, sanding, sawing, or grinding.
Before the shop filter you could hardly see across the shop after 10
minutes of welding. Since I installed the filter the air stays clear
rearguards of how long I'm welding.
The house is a different matter. We have carpets and cats. It doesn't
matter if you vacuum every day, the filters load up with a very fine
dust while the cat hair accumulates on the grating over the screens. It
is a weekly job and BTW we have both an electrostatic whole house filter
and portable Hepa filters.
Carpets, Humans, and pets really raise the need for cleaning and my den
is an off the beaten path location...Although my cat has been known to
make late night visits to check on me.
73
Roger (K8RI)
## fine screens are a pita to install on typ 120mm type fans. You can buy the
proper filters
for any of em, dirt cheap. They just mount to the 4 holes. What mounts to the
4 holes is the retainer
They wouldn't have been my first choice except I already had then and
the price was right. They are quite effective at removing dust, but
screen fine enough to do that certainly reduces air flow substantially.
I'd not use them where air flow was essential, like the 4CX3000
project...If I ever get it finished. The "one handed approach" has
certainly slowed a lot of projects. Any one want to buy a partially
completed airplane with 300 HP engine and prop? I need the space and It
is the lowest priority project and most likely will see little attention
in the future.
73
Roger (K8RI)
for the filters. The actual filters are removable, and washable. Their only
drawback is they reduce airflow
quite a bit, at least on the low speed, 55 cfm type fans. You can get the
filters in different densities.
## simple wires screens will keep out bugs and that’s about it. the above
filters really keep out the dust.
I picked up 4 of em for a new cabinet I have, that has 4 x fans on the very
top, blowing filtered air into the cab,
pressurizing it. Not much heat in that cab. the idea was to pressurize it,
then heat comes out the rear louvers,
then no dust can ever get into the cab, even with fans off.
## the fellow at the local store tells me the military base in town bought hundreds of
em the week before. telco’s
will also use em.
## I use finger guards on one side of the fan..and the filter on the other
side.
later... Jim VE7RF
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