Re: [Repeater-Builder] Re: 12vdc or 120vac Fan?

[[EMAIL PROTECTED]]

Thanks Mike

since we are going to run dc for portable use I will check while it is on the 
bench.bob

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Re: [Repeater-Builder] Re: 12vdc or 120vac Fan?

[Mike Morris WA6ILQ]

At 11:02 PM 3/19/05, you wrote:

>Hi Yall
>I missed the beginning of the thread on the 12 volt fans would someone 
>clue me in on filtering.
>
>Thanks .bob

It started on 3/18 with message 38409 from kc4wgh

Check the archives at 


The thread boiled down to, in my opinion, that in an
AC environment, you want to use AC fans.  In an
environment where the system is going to run on DC
(i.e. battery backup) you need to run a good LC filter
on the fans as many electronic commutator fans will
feed trash back on the power feed, and if there is not
enough filtering the trash will get into the system audio.

Personally I have an old dirty fan (electrically dirty) that
I use for testing...
It's a no-name 120mm size with the only identifier
"Made in China".

I put that fan on the RX +12 power feed and see if it
affects the RX audio. If it does, I fix the filtering in the
RX, not the fan !

Likewise I put it on the TX +12 power feed and see if
it affects the TX audio. If it does, again I fix the
filtering!

If the power filtering in the RX or the TX is marginal,
I want to know BEFORE the new box goes up,
perhaps at a site that I can't get to from first snowfall
to last snowmelt (which may be anywhere from
mid-march to late april).

Mike WA6ILQ





 
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Re: [Repeater-Builder] Re: 12vdc or 120vac Fan?

[[EMAIL PROTECTED]]

Hi Yall
I missed the beginning of the thread on the 12 volt fans would someone clue me 
in on filtering.

Thanks .bob 

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[Repeater-Builder] Re: 12vdc or 120vac Fan?

[Coy Hilton]

--- In Repeater-Builder@yahoogroups.com, Ken Arck <[EMAIL PROTECTED]> wrote:
> At 02:32 PM 3/18/2005 -0700, you wrote:
> >
> >I would go with the 120.  12volt fans have a bad habit of 
dirtying the
> >DC voltage which can ocasionally be heard in the repeaters audio.
> 
> <--Not with proper filtering it doesn't. Besides, I believe that 
most 12
> volt fans use less power than their 120 Vdc counterparts.
> 
> Ken

Yea, the 12V fans don't move nearly as much air as most 120 volt 
fans. If the repeater is on emergency AC power it will make life 
simpler to use the 120 V fans and run them all of the time. 
If you know that it's likely that you will be running on emerency 
battery power, then I would use 12V Blowers with the required 
filtering and a thermal switch of your own choosing.

73







 
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