[Amps] Peter Dahl Transformers

[Roger (K8RI)]

On 2/21/2013 7:02 AM, Jim Thomson wrote:
> 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

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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