Hello,
New Guy Question: I have dug up my backyard and installed 1.5″ conduit from my basement to my storage shed where the grounding rod & surge protector connecting to a wire antenna will live. I installed the conduit thinking of expansion for other cables, control wires, etc. Or at least that what I tell myself…
Anyway, this is approximately a 100′ run of coax. I was thinking of buying a DXE-400MAX pre-made cable from DX Engineering. Yet I walked away from the September meeting thinking the people in the club preferred 213U coax. And do people buy pre-made cable of terminate them themselves?
The New Guy just looking for knowledge. This is my FIRST coax so I’d like to buy the best stuff. The costs between the 400 & 213 are about zero. Is one more flexible than the other – there are a few 90 degree conduit turns. I figure I’d use 8X from the surge protector to the wire antenna.
Thanks, Mike
KB1RFJ
Mike,
Good question! My personal rule for Coax is buy the best you can afford. I use RG-8X for my magnetic mount mobile antennas because it’s light and flexible, and better than RG-58, which I consider junk because loss grows so fast. RG-8/U used to be good cable, but so many cheap copies are out there (Radio Shack, etc) that I use RG-213/U or LMR-400. These two are nearly identical in performance, flexibility, and power handling plus loss. There is better cable, but it gets expensive fast. I assume you are going to have a coax switch at each end so you can use multiple antennas and maybe rigs. It sounds like a remote control switch in the shed for various antennas. I recently did this so I have only one coax leaving the building.
If you have any additional questions, please ask. There is a ton of experience in this club, and they are very happy to share!
73, Mike, K1DM, President, CTRI Contest Group.
Mike,
Here is the coax used at Radio Ansonia. Jefa is advertised on E Bay where I purchase 500 feet for $175.00 per 500′ spool. Shipping is $19.00.
http://www.jefatech.com/product/LL400-B500/Low-Loss-400-Coax—500-ft-Reel.html
I find it to be a great performer at a good price.
One recommendation…the next time you install underground conduit DO NOT install any conduit under 4″ diameter. Use street elbows at all turns. Even 4″ gets filled up faster than you think.
Just my .02 cents
73 Dave
W1CTN
Radio Ansonia
Mike,
I use The Wireman’s CQ Flexi 4XL coax. http://thewireman.com/coax.html It’s expensive but it’s what I like. I agree with the adage about buying the best you can afford but I’d also say that for runs of 100′ at frequencies from 150 mHz and down, it’s nothing to get excited over (unless you’re running QRP). A high quality coax will survive longer and that’s important to me, since my coax runs just lay on the ground. I use the same coax for HF, 6M, and 2M. I also buy my coax in rolls and cut to length.
The other thing to mention is ladder line. If you’re using a dipole of some sort, you might want to consider running ladder line to it from the coax on the ground. It’s very low loss but more importantly, if you’re like me and use a dipole to cover multiple bands, ladder line gives you more flexibility when used with a tuner. I have an 80M 1/2 wave inverted vee that I use on all bands including 160M, fed with coax and about 35′ of ladder line.
Connector quality is also important, so definitely buy the best you can afford. Silver with teflon. And I agree with Dave on the conduit size. It’s always good to have room for expansion.
73,
Pat, NG1G
Hi Mike,
I have been using the same cable that NG1G uses from the Wireman. It has served me well. I recently purchased some Times LMR400 from The Antenna farm, as they had a special on it (which I just noticed isn’t there anymore) but I haven’t used it yet.
It’s probably not a huge deal, but I work in the CATV industry and we always use flooded cable when we pull cable into conduit. It’s got some sticky stuff inside the jacket that keeps any water that might get into the cable from migrating through the cable. I don’t bother with it at home because it’s such a mess to work with.
As others have said, you can never have too much conduit in the ground. If you’re digging a trench, you might as well put in as much as you can afford.
I also use PL259 connectors from the Wireman (part number 1126). These have a center conductor that you solder and you crimp the shield. It doesn’t seem to affect anybody in the club but me, but I have an awful time trying to solder the shied to the body of the connector. You need the crimp tool (don’t use a pair of pliers) to make the crimp and you need to heat-shrink the completed connector when it’s outdoors. But I’ve had these in the air for about 5 years and I’ve never had one fail.
For any connector installation, you should get a good prep tool. I bought one from DX Engineering part number UT-8213. It really beats the old knife. The crimp tool I use is from Cable Prep and their part number is HCT-350. If you want to go this route, you should call them and make sure you get the correct die for the tool. The one I have is for PL259 connectors on LMR400. Their phone number is 800-394-4046.
As Pat mentioned, ladder line is a good option for multi-band antennas. The loss from the tuner to the antenna is much less under high SWR conditions then it would be with coax. Remember that your tuner just matches the radio to the feedline. So, with a good tuner, you may have a really high SWR between the tuner and the antenna (unless you’re tuner is a remote tuner located at the antenna-feedline interface). There are lots of theories about installation of ladder line. For exam[le, it shouldn’t run closer than a few inches from other conductors. I’m not sure how well it would work if you ran it inside a conduit alongside a piece of coax. But you might want to research that. You’ll find a gazillion theories and opinions.
Good luck with the installation.
73
Chris, KA1GEU