Posted: 2/6/2014 12:39:32 PM EDT
I live in a deed restricted subdivision, so I can't have any outdoor rooftop antennas. For the last few years I've been operating an SG-237 Smartuner with pretty good results. One side goes to a random length of black WD-1 field phone wire and the other end goes to a ground rod.
Whenever I operate, I run the coax through the basement window, but I'd like to make things a bit more permanent, especially now that it's so damn cold. I bought a 12-inch SO-239 connector and I want to drill through the exposed cinder block foundation to install this. Am I correct in assuming the top of the wall is hollow and hasn't been filled? 
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That's now exactly how I'd do that... I'd put a junction box outside, and run conduit through the wall to it. Then fish your coax through it.
How much did that feed through cost? But back onto your question: There's no telling. It might be filled solid with gravel, or it might have steel rebar in it, or it may have both. I've seen them where they were filled with extra concrete from pouring the foundation... |
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Alternatively, take a glass pane out of a window and replace with plexiglass. Drill the plexiglass using a high speed drill with low pressure to avoid cracking the plastic. A small hole saw will perhaps do a better job. Mount a/ several short version(s) of the SO-239 feed through in the window. Drilling the hole(s) ahead of time is worth your while. On the antenna system itself, put down radials, as many as possible; though, many short ones are better than a few long ones, attach these to the ground lug on the tuner and run the radials away from the direction of the antenna wire as much as possible so as to spread the field between the two wires as much as possible. When the snow goes away these may be held down with lawn staples etc. This will make a huge boost in the efficiency of the antenna system. 73, Rob |
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How much did that feed through cost? Quoted:
How much did that feed through cost? I got it for under $20 at the Dayton Hamvention. Quoted:
Alternatively, take a glass pane out of a window and replace with plexiglass. We're planning to replace the window with an egress window, so that won't work. That's why I'm looking at through-the-block options. |
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Quoted:
That's now exactly how I'd do that... I'd put a junction box outside, and run conduit through the wall to it. Then fish your coax through it..... Quoted:
That's now exactly how I'd do that... I'd put a junction box outside, and run conduit through the wall to it. Then fish your coax through it..... IMHO, this is a better way to do it. The problem with the feed through is thermal insulation. They will conduct cold and frost up inside on the warm, humid side. Do a search on some of the ham forums and see all the revelations about this phenomenon. Conduit allowing the coax to come through is a better solution. ...But back onto your question: There's no telling. It might be filled solid with gravel, or it might have steel rebar in it, or it may have both. I've seen them where they were filled with extra concrete from pouring the foundation... Stay away from dead center of any given concrete block and that should help keep you out of the solid web area found inside any unfilled block. Normal foundation construction these days generally entails laying up a concrete block wall with the cells empty, and then a rebar inserted about every 48" on center, which is then solid grouted in with concrete. Thus results in a solid filled area about 8-10" wide. If the wall has a very high fill, exterior grade vs the basement, these reinforced cells might be as close as 24" on center. A wall deemed 'structural' and or acts as a retaining wall. it might be filled 100%. Lightly tap on the blockwork with a hammer and listen for one web to be hollow. A star drill (chisel with an 'X' point) and 2# hammer works well with hollow block. Start with a small chisel, then use one of the required size. A masonry bit in a hammer drill is the proper tool to use if the cells are grouted solid. |
| Conduit is the way to go. Suck it up and drill it....just be careful when it punches through the core in case someone fished something through the block that you are unaware of. Hydraulic cement around the outside of hole(aka water-stop), foamy stuff around pipe inside block and fire rated caulk inside. Some of the larger Lowes and Home depots have it in stock, otherwise you can get it from a professional electrical or plumbing supply house. Have trouble finding any, drop me a pm, I have an extra 20 -30 tubes laying around and will just send you one. Not sure what you are using to drill it with but if you are using a big hammer drill, remember re-bar will stop a bit dead. Just be careful and stay warm, it's an easy install and should only take about a half hour. Pick a warm day for the hydraulic cement. |