I know the question was rhetorical but … the answer as always is, it depends. Depends on what? On what trade-off(s) you want to make. Yes, didn’t your mother tell you, there are always trade-offs in all aspects of life.
How many times have you read on this and many other websites: “What’s the best antenna / HF rig / Morse paddles /etc ?” There is no single correct answer when there are many slightly-different solutions.
One trade-off dimension in SOTA is radio performance versus convenience/comfort/safety of hillwalking. Most of us move along this scale for different occasions. Solo-activating a 10-pointer in harsh winter weather I would usually be at the comfort/safety end of the spectrum and take only a 2m FM handy and whip antenna. Participating in an all-day SOTA event on a 4-pointer in warm summer weather, I might take several elaborate antennas and multiple rigs. For most activations I’m somewhere in the middle: I want a multi-band HF antenna that’s quick to deploy even though it’s not going to give me ultimate Dx.
So, this debate about the ‘best’ coax feeder has to be set in context of your expectations. I’m with Andy @MM0FMF on RG174. My rucksack [especially in winter] is packed with winter clothes, bothy bag, lots of food, etc so space and weight are at a premium. If I lose half an S-point compared to using the ‘best’ coax, that means nothing if I can fit everything in the rucksack and still get a large number of contacts.
BTW: regarding RG174 losses on 10m, I find propagation conditions are more important than power level. If 10m is ‘open’ then it makes very little difference if my KX2 puts out 10W CW or 7W CW, where as if conditions are poor, 100W up the spout won’t help you. No, I won’t carry a ‘better’ coax cable just for 10m.
Is there a reason not to use it?
For the summits in DM carrying additional 100 g normally is not a problem. So I do not see the need to use RG-174. When using a 5 mm cable, why stick to the old RG 58 when Aircell 5 or Hyperflex 5 are available? Attenuation normally is not a problem with a few meters of RG 58, but I cannot see any advantage of RG 58.
I have been using 5 m of RG 58 for my HF activations for many years. For VHF/UHF I switched over to 5 m of Aircell 5 (Hyperflex 5 was not available at this time). As I use the same cable for HF and VHF activities now this is my standard cable for HF, too. I have used it many years and propably more than 200 activations. No problems with the foam dielectric due to mechanical stress up to now.
The big advantage of an EFHW: You can reduce coax cable length as you can sit near the feeding point of the antenna.
Generally this works fine, as discussed in Should I use my vertical horizontal? More results - #5 by DB7MM
But especially on DM/BM-344 this is a bad idea: All the telecom equipment installed in the lookout tower causes QRM when your antenna is near to all the cables running down down to the ground.
So for my last HF activation I set up at the bench a few meters beside the lookout tower. With a EFHW and a pole this should work fine.
I had a feeling 7W out would not be catastrophic. I’m not sure about 10W out though. It would be interesting to test the output with a spectrum analyser, to see if the emissions profile remains within spec.
73 de Matt
Exactly. As Old Father Time keeps winding me in I’ve become much more sensitive to excess weight carried. Very obvious when I have the microwave gear with me such that I may stop taking some HF antennas with me on those trips. They may only be a few hundred grams for the dipoles etc but with all the uwave weight and the fact I don’t tend to get on the HF bands on these activations there is little point carrying it.
Talking about loss I was surprised to see the loss in RG316 and especially RD 316 (aka RG-316D, RG316 that is double screened) is quite a bit bigger than RG-174. I have a 25m length of RD-316 obtained for pennies which was about to be cut and become the dipole’s main feeder as I replace my RG-174 coax every few years now as a preventative measure. I had one length go intermittent years back that saw off the 817 drivers and PA. I change the feeder every so often as it takes a hell of a battering, winding and unwinding, supporting its own weight and getting blown about in the wind. For the cost of a length of coax every few years it makes sense to me.
I invested in a crimp tool and some RG-174/RG-316 crimp BNC plugs. Once I had solved the Edward De Bono lateral thinking challenge in how the crimp plugs fit, it was quite straight forward to get what I hope is a mechanically sound connection that also looks rather professional. I added some extra lengths of heatshrink to improve the rigidity. We shall see how it goes. The connectors do look neater but, of course, they’re single use unless you can buy the shield crimps separately?
The ratchet crimp tool was about £18 and does RG58/59, RG-174/316 sized cables. You can get extra jaws for bigger cables but the extra jaws cost almost as much as another crimp tool! I also bought one of the coax strippers that does RG-6/58/59/174 cables for about £5. It really was quite pleasant to able to prepare the cables so easily. I should have bought one years back rather than playing with Stanley knives!
I suppose it was inevitable that I should repeat your experience Andy @MM0FMF.
Measuring the VSWR of my 20m linked dipole in the garden [with a view to changing it to a 20/17/15] I couldn’t understand why the VSWR minimum frequency jumped about each time I scanned it. Then I noticed that the RG174 cable / BNC plug at the rig/AA end was intermittent when touched [something I wouldn’t have found without the AA].
So I’ve ordered a ratchet crimp tool and RG174-compatible crimp BNC plugs [from CPC Farnell]. I hope it’s as straightforward to do as you indicated. Have your ones been reliable?
I bought cheapish crimp tool from someone I can’t remember. I have bought a variety of RG-174/316 and RG-58 BNCs from various people. They’re all probably Chinese but will be fine for HF use. Not sure what they would be like on 2.3GHz, there could be all sorts of nasty resonances and issues, but HF is fine.
The key is accurate stripping. Yes, make sure you play the correct music when removing your clothes in a provocative manner. No, I’ve got a bit confused there…
Practice stripping the end and assembling the parts. If you use a Stanley knife etc. make sure the blade is decent. Some of the BNC connector centre pins are solder fit and some are crimp-able. Prepare the cable and dry-run the assembly many times to make sure you see how all the bits go together. My connectors came with some lengths of heatshrink to finish off the job and I added extra to reinforce the termination. DON’T FORGET TO PUT THE HEATSHRINK ON BEFORE CRIMPING! You can’t unsolder it to get the bits onto the cable you forgot to fit like you can with non-crimp.
My latest feeder has only done 6 activations so far but it looks so much neater than the other one it HAS to be more reliable! I think, like all these things, it depends on how you treat it when deploying and retrieving it.
The BNC at the balun end of the RG174 coax is fine because I’ve tie-wrapped a small loop of coax to the balun so it doesn’t get disturbed much. The coax is dedicated to this antenna so it never gets unplugged. Also, I’m always gentle when removing/replacing the three-winder arrangement in its carry bag. But inevitably the BNC at the rig end gets wiggled about during unwinding / rewinding & plugging / unplugging to the rig. So, it’s not surprising that it goes dodgy after dozens of activations.
