Hey Gent's,I will be geting a 396xt, and putting in a base antenna about 20' up from ground, and only needing about 25' of coax, to go through the wall to the room, Question,...what size/grade of coax should I get, for the one time only "good to go" install, to power my Handheld for the best and long lasting "no need to upgrade" coax and connectors.......THX..
Gary.
You're missing some important details in your question, what frequency (just the band will suffice)? Coax that will do just fine on the VHF-Low band may have way too much loss for the 800 MHz band. What is your budget? You can get by using some RG-6, but if you spend more you'll have lower loss.
I'll assume that you'll want the worst-case situation, which is the 800 MHz band (it'll still do fine for the lower frequencies) and a moderate budget. I'll also throw in a few options so you can adjust based on the missing information.
First and foremost, use a quality name brand coax (Belden, Times, or Andrew are good). You may save a few bucks up front using some cheap and/or no-name coax, but you'll never really know what you're getting. It may be some very good stuff (a name brand produced for others to resale under their own brand) or some very poor quality junk - which you get depends more on who had the best price at the time than any other real factor. Don't just rely on price since folks may sell junk for top-dollar so it sounds like top-quality when it's really just way overpriced junk! See this thread (
http://forums.radioreference.com/coax-cable-discussion/263871-coax-decision-wilson-vs-times.html) for a discussion on this topic.
Second, try to minimize the use of adapters. If you have a "custom made" cable, you can probably get different connectors on the ends to match what it will connect to (e.g. a PL-259 on the antenna end and a BNC on the scanner end). Premade cables generally have the same connector on each end so pick the one that matches one end (antenna end if possible) and use an adapter on the other end.
Third, use a coax loss calculator (like this one from a quick Google search -
Coax Loss Calculator) to compare the various types to see what may work best for your situation. Go for the lowest loss you can afford, but don't sweat the absolute numbers too much. Although 3dB is "half your signal", this doesn't tell the real story since the amount of signal is only critical if it's below a minimum level or above what will overload your scanner's front end. If your signals are very weak, that extra dB may be important, but if they're only a bit weak you won't notice it.
Generally the larger the coax the better. Coax can be had from around 1/16" to 8" (perhaps even larger). The 1/16" will kill the signal if used beyond some short internal jumpers and that 8" stuff will provide good loss numbers for antennas on those 2000' TV broadcast towers. For most scanner folks, some 1/2" coax should do fine (e.g. RG-8 will be good, LMR-400 better, and LDF4-50A great). Note, I said RG-8 so don't confuse that very similarly named RG-8X, which is closer to RG-58 than it is to RG-8 as far as size and loss in the VHF & UHF frequencies (it's great for HF though!).
More specifics for your situation. Try to get some LMR-400 if you can. It's a bit stiff, but quite low loss and should do great for your 20 - 50 foot run. Keep the bends smooth and fairly large since it may crimp if bent to sharply (ruining that nice loss number).
You probably can even get by with some RG-6 since it's designed for low loss at most scanner frequencies. It also looks like standard Cable-TV stuff (it actually is) so visually it's a good choice as well. If you move you can leave it there as a "TV feed when the cable is out".
