[amsat-bb] duplexer used as a filter

Kevin M n4ufo at yahoo.com
Tue Jul 28 08:05:35 UTC 2015

> Resist any temptation to seal up every crack and crevice of the diplexer.

> be sure to leave a weep hole or a small gap perhaps where your cables come in through the bottom so moisture can escape.

Cannot agree with the above enough... You NEVER want to try and seal it up completely; mostly because you can't. (the block of epoxy being the exception) Warm day, heat beating down on it, cool rain comes, case temperature drops quickly, air inside will condense and suck a hole in your weather seal. Now you have moist air trapped inside... no weep holes. It's the same reason you never seal both ends of hollow feedline.

Are you thinking of using preamps? Then I want to suggest you try TWO diplexers... one on each feedline before the preamps. The 'unused port' on each can be capped with a simple antenna connector and a 50 ohm 1/4 watt resistor across it. Now, need room for all that? How about a tactical gear case...

I've found the black cases from MCM electronics (~$25) and antenna brackets at the hardware store (~$5):



It's just a suggestion... your mileage may vary, batteries not included, attempt at your own risk. =^)

73, Kevin N4UFO

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