*PRODUCT WATCH* Coaxial Cable Types

According to one Dx Adventure Radio Club member, “Coax is our radio’s lifeline through which RF flows – like adrenaline through the veins of a DA-RC DXpeditionist…”  He’s probably right too!  Also known as ‘feed-line’, coax is an important consideration for shack success that is often overlooked by the performance conscious DX enthusiast.  Often, a great deal of money is spent on a flashy transceiver, complex antenna system, big amplifier, microphone, etc. and not much on the cable…  This is not good!

As we all know, the signal from our rig’s transmitter goes through a length of coaxial cable consisting of two concentric wires, to the antenna of our choice, which is then broadcast to all corners of the globe (Well hopefully anyway, lol).  Maybe not just one antenna too…  Perhaps 2 or 3 working co-phased, simultaneously or individually as is the case with 224DA001 Tamuka’s antenna farm on Tarawa Island.  Having good coax then is essential for some quality T.I.T.S. (Time In The Shack)!

“So what’s the best coax for Freeband or Citizens Band DX’ing,” you might ask?  “Which type should I be using in my radio shack?”  It depends on your circumstances I suppose and how much money you’re willing to spend.  Some of the common types of coax that you’ve probably heard of are RG-8, RG-58, RG-213, Belden 9913/9913F, LMR-400, and ‘hardline’.  Unfortunately, some of these have high loss on 27MHz and get even worse as SWR increases, leaving your transceiver sounding more like a silent movie rather than a hub of DXCC RX.

Not only is it essential to use low loss cable with a thick, tight braid, but you must make perfect connections at the coax ends or even higher losses will occur.  It’s also important to note that old coax has high loss also.  Sometimes, the cable’s properties break down over time, resulting in very inefficient cable.  If you’re still using coax from the CB boom in the 1970s and 80’s, for instance, then it’s probably time to scale the tower and change it.  You’ll notice the difference, that’s for sure!

My previous choice of cable, RG-213, is the most commonly used for 11m base stations behind the thinner and cheaper RG-58 version and represents an improvement of massive proportions over the RG-58 family.  Apart from being heavy duty, tough and durable, it has a loss factor of only 1.35 dB for every 100 ft compared to the RG-58’s 2.35 dB.  That’s quite a significant difference.

Although it is quite expensive, my current choice of cable is Belden 9913 which has a loss of just 0.7 dB in every 100 ft of cable.  This is a special type of coax which was recommended to me by 14DA911 Eric as it has two outside shields.  As a result, it’s super efficient and my latest batch of the stuff is thankfully much more flexible then my previous buy of the same product due to a few changes in materials.

I’ve heard some discussion about the correct length of coax but in my opinion the shortest length that makes it from the radio to the antenna is the best.  Having used all the common types of feedline over the years, I can safely say that my favourite type is the Belden 9913, though I’d be keen to try the hardline variety on DXpedition travel which I have heard is pretty efficient.

73 de Darren, 43DA001/010