Join Date: Mar 2013
Thanked 3 Times in 3 Posts
Rep Power: 3
Re: VHF antenna and cable recommendation
If it were me, on a 35' mast, I'd use LMR240 and crimp-on connectors like Mainesail recommends. The LMR240 is high quality, low loss cable that is only 1/4 inch thick. It's easy to route through tight spaces. The loss is about the same as RG213. Per 100', at VHF freq's, the loss is around 3dB, RG213 is about 2.8dB, & LMR400 is 1.5dB. Considering that you will most likely have significantly less than 100', the difference in loss between any of these cables is negligible. Comparing to LMR400, your signal attenuation would be just 1.5dB difference between the two. In real-world operating, you would not be able to distinguish that small of a loss in signal strength.
People will get on here and talk about about what percentage of signal -3dB loss is, but it doesn't equate to the same percentage of actual range. I'm just saying that if you had the cables and compared side by side, you wouldn't be able to distinguish which one was the higher loss cable, neither would a distant station copying your signal.
LMR400 is only about $0.30 per foot more and is a little more durable because of the size. RG213 is OK, but more expensive than LMR400. All are fine for a VHF installation, and if you can get one for a good price, go with that.
I'm an RF engineer and have been in wireless communications since the mid eighties. We have been using crimp-on connectors for just as many years. I recall a debate over what was better, solder or crimp, back then, but really thought it had been put to bed already. Soldered connectors are no more reliable than crimp-on in any VHF installation. In fact, the only time they are superior, is in certain UHF/microwave installations that are more susceptible to passive inter-mod because of dissimilar metals between the connector and cable. They still use non-soldered connections most of the time anyway. Considering that you will likely be using PL259 (UHF) connectors, which are possibly the most difficult to solder the braid properly, I'd recommend you pick up a crimping tool after you decide which cable to go with. You can find a cheap one on eBay for about $30. Seal the connectors. It doesn't matter what type you use, they will all eventually let moisture in if exposed. I put 3 concentric layers of adhesive lined heatshrink at the base of the connector to strengthen the joint. This makes the cable/connector extremely durable. Then wrap in appropriate weatherseal tape. Self-amalgamating, butyl, silicone, etc. You can acquire a small amount from wherever you purchase the cable & connectors. Just make sure you install it the way the manufacturer recommends. For example, butyl is not meant to be exposed, but wrapped in a rubber tape similar to regular electrical tape. This will ensure you will not have to go up the mast anytime soon. If you need to splice the cable through the deck, just need to extend with a thinner cable, or have two shorter pieces, etc, don't be concerned about excessive losses by adding connectors inline. A couple of connectors, if properly installed, will have such a small impact on overall performance, that you would need test gear to detect it. Soldered PL259 connectors are installed poorly so often that the performance is degraded. Good luck with the installation.