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Re: Feeding DC to the DEM Pre-Amp



I've just done the same (built the 13ULNA kit). I took a
slightly different power approach. 

I coupled the preamp directly to the DEM downconverter using
a male-male N adapter. On the DEM converter, Don, W4VQA had
previously removed the RCA jack that they used as a
secondary power source, and replaced it with an F connector.
I moved the wire to the input of the 7809 regulator, so that
the +12V or so that I feed up the line from my bias tee,
continues out that connector.

On the preamp, in place of the power feed-thru, I installed
an F chassis connector and wired it to the +V input. I then
made up a short RG-6QS jumper with weatherproof F connectors
on the ends and coupled the two power connectors together.

Also, since we will also be testing this combo with a
TransSystem 3733, I installed an F chassis connector on the
3733 cover near the regulator end of the unit, and wired it
to the regulator input. I'll make up a similar RG8 power
jumper for that as well. My 3733 has the N adapter on it in
place of the dipole.


73,
Art N3OY

G0MRF@aol.com wrote:
> 
> Hi.
> 
> I've just finished building the 13ULNA kit from Down East Microwave and then
> tried to figure out how best to power it.
> 
> The PCB has a quarter wave RF choke printed on the board at the output which
> allows DC to be fed down the Coax.
> 
> I've fed DC to the pre-amp from a Drake converter using a couple of surface
> mount components for a simple bias tee. It's not fully tested yet but, an
> initial test listening to an ideal pass of UO-11 with a helix was OK.
> 
> www.g0mrf.freeserve.co.uk/drake.htm
> 
> 73
> 
> David
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