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Old 21-Dec-2019, 4:50 PM   #31
Retired A/V Tech
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,569
Any plastic housing for a PCB balun will trap moisture from condensation. The best designed housings have "weep holes" at the bottom to allow the enclosure to breathe and drain moisture.

Older Channel Master preamps like the original 7777 with two antenna inputs not only had the connectors on the bottom for weather protection, but the bottom plate wasn't tight against the housing. This provided a small gap at the edges of the plate to allowed the enclosure to breathe.

The recent preamps sold by Channel Master have a gasket at the edge of the plate and coax connectors that have an internal seal which makes it difficult to insert the center conductor of the coax. I'm not convinced that trying to make the enclosure hermetically sealed is an improvement.

Attached Images
File Type: jpg HDB91X Weep Holes.jpg (75.7 KB, 277 views)
If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 21-Dec-2019 at 6:51 PM.
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