DIY feed-through panel for your antenna cables

DIY feed-through panel for your antenna cables

I'm fortunate that I have a nice warm space inside to use as my "shack", but logically my various antennae are outside, so how do I get the cables from the antenna to my radios?  I don't want to go drilling holes in walls etc. because that would make me very unpopular with my wife and it would also invite leaks, drafts, pests and other generally unwanted things.

Since I have a large window near where my gear will be located, I hit on the idea of making a filler panel and then attach a bunch of connectors to it.  Naturally I wanted it to look as nice as possible.

The only modification to required to the window is to remove the insect screen.  In my case, this is fine since we never open this window anyway.  Otherwise you may consider making up a narrower screen.

The window closes up on this panel holding it in place and keeping everything sealed up.

I chose bulkhead connectors because I don't need to solder any connections on the panel, which if you're up a ladder will be an added bonus!

The metal strip is important because it gives you a solid common earth connection, and it is so much easier to mount connectors anyway.

Materials

DAR Pin 800mm W x 10mm x 1800mm L

Aluminium strip 50mm W by 3mm T x 1000mm L

SO-239 bulkhead connectors (Ebay)

BNC bulkhead connectors (Ebay)

SMA bulkhead connectors (Digi-Key)

F-Type bulkhead connectors (Digi-Key)

N-Type bulkhead connectors (Digi-Key)

Insulating bushes with 4mm - 5mm hole

M4 x 30 screws

M4 Wingnuts

M4 Washers

M4 nuts

Draft excluder foam 10mm wide.

20mm hole saw (not essential, but it will save you a lot of time)

I have not specified quantities because you can mix & match to suit your needs.  I used the following as a starting point, based on what I could imagine needing in the future:

SO-239 x 4, BNC x 2, N-Type x 2 F-Type x 2, SMA x 2, Balanced x 2.  Your choices my vary.  This takes up about 650mm of my aluminium strip, giving me plenty of room for future growth.

Construction

Cut the timber to the inside length of the window opening (1150mm in my case).  Test that this fits comfortably in the window before we go any further.  With that done, measure out where to locate the aluminium so it is centred on the panel and put it aside.

Now lay out where your connectors will go.  I started from the end, rather than the centre because I wanted to be able to expand my options later, but you're free to do as you choose.

To my way of thinking, the larger connectors look good at about 30mm between centres, will the small SMA and F-Type looked better at 20mm.  My balanced terminals are spaced 25mm apart.  When you're happy with your layout mark up your positions and drill away.  Make sure to check out the respective diameters for each type of connector you plan to use as it's easier to make a hole bigger, but really hard to reduce the size.

This might also be a good excuse to invest in that drill press you always wanted too!

When you're finished with the drilling and/or cutting, you can dry-fit all the connectors you have.

Another handy hint is to use a "Sharpie" type marker because it will clean off with just a little isopropyl alcohol.  Of course if you have a tin of Prussian Blue, please use that and send me some :)

For clearance through the timber, I used a 38mm hole saw, which gave me plenty of room to adjust connectors.

The only difficult connectors were for the balanced lines.  This is because there's not convenient bulkhead connector that I could find.  Originally I planned to use rubber grommets, but these didn't seem to sit well in the 3mm aluminium.  I found I had a collection of insulating bushes for power transistors.  The next photo shows how I assembled the connection.  You will note that I did not remove the screw head, because it means you can't lose the wing-nut when you are up a ladder making a connection.  You'll thank me later!

With everything cut and drilled now coat the timber with marine-grade varnish.  I gave my timber panel three coats all around to make it as resistant as possible to the elements.  Give this about 24 hours to harden after the last coat because by then the fumes will have dissipated as well.

Before fitting into place, stick the excluder all around the edges of the timber.  This allows you to "crush" the panel into place and get a secure seal.  As a finishing touch, make up some labels for your connectors before presenting to the head of the house for approval.

But now you're thinking "Wait, he's got all those connectors exposed to the weather".  I thought of that too.  Grab some balloons and cable ties and secure them over the unused connectors to keep them clean and ready for use.

While I'm at it, someone is sure to point out that you can buy a panel similar to this from a big radio accessories company in the states.  I discovered that after I started planning mine out, but before you rush off and order one please consider the following:

• In most American houses, the windows open vertically, whereas most Australian houses built since the 1980's open horizontally.
• They will be imperial sizes, and might not fit out metric (more-or-less) windows.
• It's bulky so the shipping will cost a lot
• While those folks have a really nice product, there is a certain satisfaction in doing it yourself.

Till next time!