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powering multiple devices at the antenna



Bob KB7ADO wrote:

Is it possible to run two devices from one in-line power supply?  I have one of the Millicom 2.4 ghz downconverters which has an in-line power supply, and I'm wondering if I can use it to run both the downconverter and the Connifer preamp.

Wayne replies:

There are several ways to do this, but I chose to add a feed-thru capacitor to the downconverter.  Inside the downconverter, the feed-thru capacitor connects to 12V.  Outside the downconverter, the feed-thru capacitor is wired to the DC input connector of my DEM preamp.  If the preamp expects to be powered via it's RF output connector, you would also need to add a feed-thru capacitor to the preamp.  At this point, it might be easier to modify the downconverter to put 12VDC on its input.

In case you're not familiar with feed-thru capacitors, they are threaded gizmos that screw into a metal housing wall.  Studs on opposite sides of the wall have a DC connection, but have about 100 pF of capacitance to the threaded flange to keep RF from getting in or out.  DC passes through, but RF doesn't.

Wayne Estes W9AE
Mundelein, IL, USA

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