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Re: Feeding DC to the DEM Pre-Amp

On Friday 06 July 2001 11:52, G0MRF@aol.com wrote in "[amsat-bb] 
Feeding DC to the DEM Pre-Amp":

> 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


This looks really cool, and as soon as I have some income (still job 
searching here) I intend to improve my S-band recieve, including a 

But just to clarify: the last photo shows the Drake with the cover off, 
with the red wire that brings the 10v forward to the new components and 
the N connector. We also see the log periodic antenna attached directly 
to the N connector.

What we *don't* see is the pre-amp. I'm assuming the photo is just to 
show the wire routing? Obviously there's no problem in having DC 
present at the antenna. But I'm guessing the photo isn't intended to 
show the pre-amp in operation, and that may confuse folks a bit; you 
may want to mention it on the web page.

But the technique itself is awesome....   

73 de Maggie K3XS

-----/___.   _)   Margaret Stephanie Leber    / "The art of progress  /
----/(, /|  /| http://voicenet.com/~maggie   / consists of preserving/
---/   / | / |  _   _   _    `  _AOPA 925383/ order amid change and /
--/ ) /  |/  |_(_(_(_/_(_/__(__(/_  FN20hd / change amid order."   /
-/ (_/   '  K3XS  .-/ .-/    ARRL 39280   /___ --A.N.Whitehead ___/
/____ICQ 7161096_(_/_(_/__AMSAT 32844____/ <maggie@voicenet.com>

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