[Amps] Peter Dahl Transformers

[Jim Thomson]

Date: Tue, 19 Feb 2013 16:36:40 -0500
From: "Roger (K8RI)" <k8ri at rogerhalstead.com>
To: amps at 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
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