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Co-ax question

What is peoples preferred co-ax for SOTA operations?

In reply to MM6ALZ:

As only relatively short lengths of coax are involved there is no disadvantage in using RG58, which is also light and flexible.

73

Brian G8ADD

In reply to MM6ALZ:

Carried most SOTA trips:

10m RG174 for HF dipole.
5m RG174 to 2m J-pole.
5m RG188 BNC->BNC extension cable.
1m RG58 with BNC cable sockets to SMA male plug for 2m/70cms handhelds.

Carried some SOTA trips:

3 cm UT-141 BNC plug to SMA socket adapter for 23 cms handheld.
2X 1m Suhner flexible SMA->SMA cables for 23 cms (good to 18 GHz)

I should replace the 5m of RG174 on the 2m antenna as it’s a bit pants at that frequency.

RG8 Brian? The 1960s called and wants it’s heavy & lossy cable back! If you are going to carry heavy cable at least buy some LMR-400 and make it worthwhile! :wink:

Andy
MM0FMF

In reply to MM6ALZ:

I use 10m RG58 for HF, and 10m “DRAKA LOW LOSS_CABLE 1.35L/3.6 AF 50 OHm” for 144 MHz 3 el. Delta Loop.

Feri

In reply to MM6ALZ:

I use 4 metres of URM-43! Single strand in the middle! Less chance of db loss but more chance of damaged coax if not looked after.

I use this on both the 3 element sandpiper 2 metre beam and the 4 metre slimjim. I will be looking for some better stuff for 70cm and 23cm as this is poor for the task.

Despite this what interests me more is why do people use PL-259 on VHF and UHF, they are such a poor choice, BNC, TNC or N is the way forward! If professionals use the above 3 types of plugs then why do we amateurs use these vile PL-259, please MR Yaesu give me an N on the back of my 817!

Matt 2E0XTL

In reply to 2E0XTL:

Couldn’t agree more about PL259s… Ns are much better, and easier to fit on RG8… trouble is most of my rigs have got SO259s on them

Taking of cables, Isn’t RG8 the 11mm “low loss” and heavy cable? and RG58 the standard 6mm or thereabouts cable… that’s what I use for SOTA for 2 metres…but only about a 4 or 5 metre length…

Rob

In reply to 2E0XTL:

Despite this what interests me more is why do people use PL-259 on VHF
and UHF, they are such a poor choice, BNC, TNC or N is the way
forward! If professionals use the above 3 types of plugs then why do
we amateurs use these vile PL-259, please MR Yaesu give me an N on the
back of my 817!

Matt 2E0XTL

Before I retired I frequently used a PUNDIT ultrasonic test set in the field. Its transducers were connected via BNC plugs and sockets. They were terribly unreliable, I always carried spare leads and was always having to repair leads after a trip, for portable work I wouldn’t touch them with a SOTA pole! In any case the front socket on the 817 is a notorious weak point. N plugs I find bulky and none too easy to connect to cable; although there is a mismatch in the PL259 the loss is minimal, so I have an N to SO239 adapter on the back of my 857 for portable work!

73

Brian G8ADD

In reply to G1TPO:

PL259’s can be awful. Some can be OK. The biggest problem is fitting them due to the uber-cruddy way you have to solder the braid on. I have some Teflon loaded 90deg PL259 that are quite pleasant compared to the CB tat that does the rounds. They’re often not as bad as they are made out… a check on the old network analyser shows them to be less horrible as the design would suggest, certainly at UK power levels. Having said that N, BNC and TNC are much preferred. Apart from the fact they’re more weatherproof, BNCs & TNCs weigh a lot less than PL259s and are easier to fit.

For those with SMA connectors on gear you can buy converters from SMA to BNC but these can strain the connector on a handheld. I much prefer to use a flylead. In my case, I picked up an SMA plug for RG-58 sized cable from W.H. Westlake and made the SMA to BNC lead I carry.

And can I have the rest of my post back please Brian :slight_smile:

Andy
MM0FMF

In reply to MM0FMF:

RG8 Brian? The 1960s called and wants it’s heavy & lossy cable
back! If you are going to carry heavy cable at least buy some LMR-400
and make it worthwhile! :wink:

Andy
MM0FMF

Thanks for drawing my attention to the misprint, Andy, now corrected. Of course I meant 58, cheap, cheerful and easy to get at any rally! I’ve never even seen any RG8.

73

Brian G8ADD

PS Sorry about your post, mate, don’t know what happened there but I have reconstructed it for you, pse check for errors!

In reply to G8ADD:
Quote: “although there is a mismatch in the PL259 the loss is minimal, so I have an N to SO239 adapter on the back of my 857 for portable work!”

N type and PL259 are identical in size, even the screw shell is the same thread (except for a Japanese special on some rigs!!!) but there any similarity ends.

I wouldn’t give PL259 any room on any rig unless forced to use them and when forced then only the type with compression glands or crimp fitting never, ever, those useless types with the soldered screen which are impossible to terminate correctly.

I feel really better for that!!

Barry GM4TOE

In reply to GM4TOE:

I have no problem with the soldered screen - I just wave a nice powerful soldering iron at it, job done!

With just a few metres of coax between the rig and the antenna, I think concerns about losses tend to be exaggerated.

73

Brian G8ADD

Hi Brian -

Before I retired I frequently used a PUNDIT ultrasonic test set in the
field. Its transducers were connected via BNC plugs and sockets. They
were terribly unreliable…

I have been using BNC crimp connectors since I used them(a lot)as a field engineer 25 years ago, and I have never had one fail!

73 Ken
GI4FLG

Despite this what interests me more is why do people use PL-259 on VHF and UHF, they are such a poor choice, BNC, TNC or N is the way forward!

I think the answer to this one is more often than not, that there is an SO-259 on the rig and another one on the antenna. This is especially true for those of us who have gear that is a few years old. What I find strange is that the V/U connection on the FT-857 is an N-type in EU and a SO-259 in the US. It may say something about what the majority of people look for. From the above I would suggest that efficiency is less important to US amateurs than compatibility. Could that be something to do with the power levels they tend to run? I wonder.

Another thing I find amusing is that the stations who run full legal limit (or more) tend to buy the very best low loss coax, be very finicky about having the best N-type connectors and keep their runs of coax down to the bear minimum. Most QRP guys seem to be not quite as fussy. I think of one station in particular who has a very inefficient antenna, his RG-58 is at least 20 years old and at least 100 feet longer than it needs to be, his PL-259s are those cheap CB ones that screw on and he never runs more than 5 watts. This guy was raving on about working some DX. The station in question was 55 and gave him 51. “See” he said “you don’t need all that power. I was only running 5 watts.” Back at home I looked the call up in my log. I had worked the same station 59 plus each way about ten minutes earlier. My friend was justifiably proud of that contact but I think he should have been prouder. He thought he was running 5 watts but due to the inefficiency of the antenna system I bet only a couple of milliwatts was being transmitted. My antenna is nothing special, just a dipole and it is fed with RG-58 and I was running 100 watts at the TX. QRP is great if you make the most of your antenna and feeder system, but most people (not just QRPers) don’t.

Steve GW7AAV

In reply to MM6ALZ:
I only need a 3 meter length of coax between the rig and the base of the vertical so use RG58, it is light and flexible, I carry another 3m as a spare or in certain cases have used it as an extension.

In reply to MM6ALZ:

What is peoples preferred co-ax for SOTA operations?

5D-FB semi-rigid cable fitted with BNC plugs without a doubt. It is very easy to handle in both windy conditions and low temperatures. I did consider N types as they are superior to BNC, but felt that BNCs were good enough (up to 23cms) if checked regularly. I have a 4m length of LM400 fitted with N types for serious 23cms operation.

RG-58 can act like a snake and get tangled in warm weather and is surprisingly awkward to handle in sub-zero temperatures. I only use it as a back up and for short patch leads, e.g. SMA to BNC.

73, Gerald G4OIG

P.S. 5D-FB - you can get about a 4.7m length from a W-3CK Watson Mobile Aerial Cable Kit from Waters and Stanton or similar outlet. The BNCs are a little more difficult to source, but Nevada usually hold stock.

In reply to MM6ALZ:

POI from D. M. Pozar, ‘Microwave engineering’ mentions N-connectors up to 11 - 18 GHz and SMA up to 25 GHz. The PL259 is probably a cheap solution for “DC”. The baby N connetor (BNC) and threaded BNC connectors (TNC) are for RF and IF.

I like the N-connectors because they are more weather proof than the other types. But for HF with a moderate power it is probably an overkill solution. The cable losses and mismatch in the connectors are important at VHF and above, but less critical at HF where the antenna height and efficiency is probably more important factor.

73, Jaakko OH7BF/F5VGL

In reply to F5VGL:
Good to see so many SOTA people agree with my Soapbox Rant!! Just a shame we SOTA Ops don’t have 50ohm F connectors! Solder free and very efficient!

Did not think my initial rant would cause such a stir!