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BCM
Durkin Tactical Franklin Armory
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Posted: 8/20/2017 5:51:24 PM EDT
Finally got around to finishing the coax window entry for new shack location. My shack desk is on the other side of the window. A short 3' run to my gear now instead of 30'.

Link Posted: 8/20/2017 6:52:39 PM EDT
[#1]
I like the copper flashing. I'll try something like that when I build mine.

Are those bulkhead-passthru UHF connectors or something else?
Link Posted: 8/20/2017 7:46:05 PM EDT
[#2]
They are UHF barrel connectors. I ditched the thin crappy nuts they came with & used some large heavy duty type. The copper plate is 3" x 6" x roughly 3/16" thick. I've had it a long time, a friend gave it to me years ago. I'm sure thinner flashing would work, you could double it up if needed.
Link Posted: 8/24/2017 1:15:50 AM EDT
[#3]
Did you make up an insulating strip for the gap between the window glass up above? That's the most difficult part of using a window for coax entry, IMO. 
Link Posted: 8/24/2017 6:58:16 AM EDT
[#4]
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Quoted:
Did you make up an insulating strip for the gap between the window glass up above? That's the most difficult part of using a window for coax entry, IMO. 
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Yes, It leaves about a 3/4" gap on top of my window being only partially open. I used some of that stiff pipe insulation this time. The kind you wrap around your water pipes. I sliced a wedge that fits snug in the gap. You can't even see the foam from either side, the window's frame hides it well. Not sure if that would work for your window type. If you have a large gap you may want to secure the foam inside so wind can't blow it out. I used the soft foam on my last window entry it & crumbled after a few years.


I used this type stuff:

Link Posted: 8/24/2017 10:57:29 AM EDT
[#5]
Looks good, very neat and tidy!
Link Posted: 8/24/2017 10:29:53 PM EDT
[#6]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


Yes, It leaves about a 3/4" gap on top of my window being only partially open. I used some of that stiff pipe insulation this time. The kind you wrap around your water pipes. I sliced a wedge that fits snug in the gap. You can't even see the foam from either side, the window's frame hides it well. Not sure if that would work for your window type. If you have a large gap you may want to secure the foam inside so wind can't blow it out. I used the soft foam on my last window entry it & crumbled after a few years.


I used this type stuff:

http://www.homedepot.com/catalog/productImages/400/c6/c6d970d9-537a-4b0a-abc1-3edaccebcbf2_400.jpg
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Nice solution!  I had just used a few stacked layers of weather stripping when I had a window entry. I moved the shack to a different room that has a picture window that can't open, and went ahead and drilled a hole for a 2" PVC pipe in the wall and installed a junction box outside. I'll be able to conceal the hole with an outlet cover one day if need be. I used a stainless pot scrubber to fill the entry on the outside to prevent bugs and mice from finding their way in, and a rag stuffed into the interior hole for a bit of thermal insulation. 
Link Posted: 8/26/2017 9:29:06 AM EDT
[#7]
What is the thickness of the entry panel material that you are using?

I'm getting ready to put together a window entry panel that has:

- UHF bulkhead connectors
- type N bulkhead connectors
- ceramic passthrus for twinlead feeders for my HF dipole
- rotator and control cable wiring (thru cable glands or maybe a screw/barrier terminal block?)
- ground

and maybe some other stuff such as cable glands for weather station wiring and the like.

I haven't considered lightning protection yet.

Bear with me as I do some calculations here - I'm writing this as I figure things out.

I was thinking of using a piece of 1 x 4 pine (nominal size, 3/4" x 3-1/2" actual size) as the entry panel.

It looks like UHF bulkhead connectors come in many different lengths. I've even seen 12" long connectors that can easily go through an external wall. The ones that I will be using are 2.0" long, which would leave 1-1/4" of barrel length, or 5/8" on either side. Subtract from that whatever thickness of copper flashing I will use (X2 if I put it on both the outside and inside of the panel), plus nuts and internal-tooth lockwashers on each side of the barrel.

The copper flashing that I have is 0.025" thick.

Each nut is 1/8" thick (0.125").

The lockwasher spec says that they're 0.07" thick.

If I haven't messed up my arithmetic, that leaves me with available thread length on each end of the bulkhead connector of 0.625" - 0.025" - 0.125" - 0.07", or 0.405" (which is about 13/32" or just over 3/8").

Is that enough for a standard UHF connector to make a snug connection? Apparently that is just enough (at the moment I don't seem to have a PL-259 or an SO-239 handy, but for comparison, the threaded portion of a UHF tee that I have is 3/8").

But what about the type N bulkhead connector? Those seem to only come in one size (at least the one that I have, which is marked with UG-30 D/U - there's a diagram for an Amphenol connector identified as a UG-30/U here, which appears to be similar to what I have, although it is 2mm longer - but the diagram seems to be lacking some critical dimensions: http://www.mouser.com/ds/2/18/C82-66-713713.pdf ).

The type N bulkhead only needs a single nut and lockwasher because it has a built-in stop (it also comes with an internal-tooth lockwasher and gasket).

Apparently the type N bulkhead connectors are intended for use on a much thinner panel, perhaps 1/4".

The overall length of the bulkhead is 1-1/2" (39mm actually, for my bulkhead connector), which is probably not going to be sufficient for the width of my proposed entry panel.

I bought some type N male crimp connectors, and it looks like those need about 10mm of thread length for a proper connection.

(to be continued)

ETA:

The 'shelf' plus lockwasher is 4mm thick, and the nut is about 3mm thick. So far, then, I have used up 2 X 10mm, or 20mm for connector threads, plus 7mm for the shelf plus lockwasher plus nut, and another 1.2mm for double thickness of flashing, for a total of about 28mm out of my 'budget' of 39mm, leaving only 11mm or just under 1/2" of thickness.

But, unlike the UHF barrel (which has no fixed shelf and can therefore be precisely positioned to provide equal amounts of thread on either side of the entry panel), the N bulkhead connector has a shelf in a fixed position. The distance from the shelf to the end of the connector (on the 'long' side) is 22mm, out of which I will need to allow for 10mm of connector threading, plus just over 4mm for the nut, lockwasher, and 2 thicknesses of flashing (or 14mm plus a fraction). That leaves only 8mm of available thickness for the entry panel material (about 5/16").

That seems to leave me several possible choices, including:

- using an entry panel thickness of 5/16" for the entire length
- cutting a 'window' into the 3/4" pine and either insetting or face-attaching a 5/16" thick section for the N bulkheads
- routing out a section of the 3/4" pine to leave a 5/16" thickness in the area where the N bulkheads will be placed
- using 3/4" pine across the entire length, and using a 1-1/4" or 1-1/2" dia. Forstner bit to inset a flat-bottomed hole on each face of the panel, leaving about a 1/4" thickness of pine in the middle, for each bulkhead connector (I would want to inset the flashing on both sides)
- laying up a 1/2" thick length of pine and an identical length of 1/4" thick pine (to get an entry panel thickness of 3/4" for most of its length, with a windowed area in the 1/2" section for the N bulkheads


I think that I like the second-to-last option, because that would allow for a smooth exterior and interior, and fabrication would be easiest, since I already have the 3/4" thick pine (although I'm not sure if I have a 1-1/2" Forstner bit - sounds like an excuse for a trip to Harbor Freight).

The last option would also leave a smooth interior and exterior (minus a small windowed section for the N bulkheads on the interior), but would take more work, since I'm not sure whether I can actually get pine in 1/2" and 1/4" thicknesses, otherwise I'd have to do some planing.

One more decision to make - maybe I should use 3/4" exterior plywood (which isn't actually 3/4", probably 23/32" instead). That might make for a stiffer 1/4" thickness to support the type N bulkheads).

Oh well, enough of my stream-of-consciousness, back-of-napkin brainstorming here, I think that I've answered my own questions.


ETA2: Maybe since I'm planning to have copper flashing on the exterior and interior, I might as well also put in a couple of slightly larger than 1/2" holes for any other type of cable that I may want to add in the future, using 1/2" copper pipe soldered at each end to the flashing, and stuffed with some kind of insulation to keep out the weather and the bugs, maybe spray-in foam sealant.
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