How should a coax-to-housing connection like this be weatherproofed? It doesn't seem like taping is going to do much good here
In my experience, the small amount of exposed thread on the SO-239 after inserting the PL-259 is the primary challenge in weatherproofing this connection. The first line of defense is to orient the housing with the connector pointing toward the ground to prevent water from pooling around the joint, particularly in the presence of ice and snow.
I break the challenge down into two parts:
- preventing water from getting to the joint
- since you may not be able to completely and forever prevent water from getting to the joint, preventing water from progressing along the threads of the joint once it has gained access
In order of application, my solution to (2) comes first: apply a very thin film of NoAlOx or similar loaded grease to the threads of the SO-239 on the housing. By very thin, I mean the threads should have a uniformly black appearance from the grease compared to their metallic appearance without the grease, and a PL-259 should screw on more smoothly. Excess grease may impair RF contact between the PL (plug) and the SO (socket). I have found it sufficient to wipe the threads with fingers or a soft cloth. This thin layer of loaded grease also prevents the PL from seizing on the SO, which can be very annoying or even make it impossible to remove the PL from the SO without damage.
My preferred solution to (1) comes in the form of rubber splicing tape. Even in my rural QTH, this product is available at the local hardware store. DX Engineering posted some helpful guidance on the use of this tape, but the essence is to remove the backing from a length of tape and stretch the tape as you wind it over to the joint, overlapping succeeding layers by about 50% on the preceding layers. A primary benefit of rubber splicing tape over adhesive products like Coax-Seal is the ease of removal: no need for exhaustive mechanical or solvent cleanup.
Properly applied tape is the appropriate solution: https://ham.stackexchange.com/a/12564/218
The box, and the connection between the connector and the box should already be waterproofed if the balun is made well. If not, you could always disassemble and put it back together with some silicone sealant, and add a weep hole somewhere for residual moisture to get out.