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Re: DC voltage to AIDC-3731AA

I believe that the minimum voltage is 12 Volts.  Some guys have taken out
the regulator internally to the 3731 and fed it directly with 12 V.  Look at
a 7812 datasheet and see what the dropout voltage is.  My guess is it's
probably something like 1.5 Volts.

It doesn't hurt having a higher voltage than necessary to the D/C.  All you
do is dissipate more heat from the regulator and that's not really a problem
since there's a lot of metal around it.  And it doesn't matter if the
voltage coming up the line is real stable or not.  That's what the purpose
of the regulator is for.



on 3/22/03 1:17 PM, Eugene H. Marks at WB2LLP@compuserve.com wrote:

> I am making a DC-DC converter for the subject downconverter to replace the
> current wall wart connected to an inverter and hopefully provide a more
> stable voltage supply to the downconverter.  Unfortunately, I see no
> marking on the AIDC-3731AA which specifies an input voltage range but there
> is a 7812 visible inside.  The wall wart says it produces 27 VDC at 300 ma.
> The Bias Tee shows 18 V.  If I plug the wall wart into 110 VAC and
> assemble the bias-tee, the coax I use with the down converter and the
> downconverter,  I measure 22 VDC at the 3731, which seems a bit higher than
> needed.   
> Does anyone have an idea what the minimum input voltage should be?

Jon Ogden
NA9D (ex: KE9NA)

Citizen of the People's Democratic Republik of Illinois

Life Member: ARRL, NRA
Member:  AMSAT, DXCC

http://www.qsl.net/na9d   <- Updated on 1/22/03!!!

"A life lived in fear is a life half lived."

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