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Fitting BNC Plugs

I noticed recently that Farnell stocks a BNC crimp tool p/n 2444451 for about £12. Their Amphenol BNC plugs are under £2.00 p/n 1704356.

Get yourself a cheap 3 blade co-ax stripper from ebay (not a 2 blade one) and some 9mm 3:1 glue lined heatshrink and you are good to go. You might want a cheap hot air gun - Screwfix does one at under £20. Don’t use a match.


I use my wife’s hairdrier.


Interesting. Glue lined heat shrink needs a minimum temperature of 120c to 130c. Most hair dryers are not hot enough to do the job well.

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How looks your wife after using the hairdrier? :wink:
(Sorry, I couldn’t resist.)


I know I shouldn’t but I simply run my soldering iron near to the shrink rubber until it contracts and grips the cable. The occasional black mark can usually be rubbed off the rubber by hand with no issues.

73 Ed.


OK, I’ll bite!

@DD5LP I have used your technique, but really, come on, this is not the way to apply heatshrink :wink:
I’ve also used the wife’s hairdryer @G8CPZ - mind my wife has short hair so she doesn’t use it.
Lately I bought our heatgun in from the garage, but it’s an evil thing that has to be treated with respect.

Talking of heatshrink, and this is getting proper geeky, but the heatshrink I use is fairly ‘stiff’, does anyone have experience with heatshrink that is more forgiving/flexible?



Hi Mark, that’s why I acknowledged that it’s not the “correct” process when I posted the comment. However, when no better option is available, it works as long as you don’t touch the tubing with the iron, then you can have a real mess, both to the tubing and the end of the iron!
73 Ed.

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Despite apparently not working for the glue-lined heatshrink Richard @G3CWI uses a hairdryer works fine for the ones I have. It probably takes longer (a minute or so) but it’s safe to use in the shack or house.

The potential problem is that while you may be shrinking the sleeving, it’s possible that the glue inside is not melting and flowing properly to create a seal. I guess it’s the difference between the amateur approach and a professional approach. I’ll stick with using the right tools for the job.

Better options are available it’s just that you don’t want to spend any money!

Many jobs back we had a brilliant heatshrink heat gun in the lab. It had a variety of nozzles you could add to better direct the airflow. Best of all it was small so you could apply hot air to a smaller area than you get if you use some big hot air gun probably designed for paint stripping. I had a look on the world’s favourite tat bazaar (eBay) and there are plenty of 300W small hot air guns that can get the temp up to 200C which are are only around £12.



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Many things from there seem quite effective at generating heat. Is it a good source for items deliberately generating heat? :fire: :fireworks: :fire_extinguisher:


AND … have the clutter of more stuff around the workshop or to carry with me if working on outside cables.

Each to their own Richard. I agree my approach wouldn’t suit a commercially sold product, but it works for my needs and some of these joins have been out in the elements for over 5 years with no problems.

73 Ed.



All I need here :

From Reichelt Elektronik in Germany
BNC at 0.26£
BNC crimp at 12.18£

and one lighter :yum:

73 Éric


Richard, your comment could sound a bit patronising.

I understand why a heat gun is needed to get the glue to a high-enough temperature. From what I’ve read glue-lined heatshrinks give you extra protection you would need, for example, for permanent outside installation where the antenna would be frequently subjected to adverse weather or chemicals.

As a mainly fair-weather activator if my antenna gets wet, it’s because I was unlucky and it (plus the mast, guying, etc) gets a good drying out once home. I use heatshrinks for extra mechanical support where the coax feeder gets flexed a lot near the BNC plug - a known point of failure. Normal (non glue-lined) ones like mine are fine for that purpose, and a hairdryer is hot enough to shrink the heatshrink to a snug fit.

I would imagine that the majority of radio amateurs do not make such equipment for a living and don’t have access to suitable tools from their professional work. Many doing this hobby on a budget (e.g. retirees like me) cannot justify buying tools they don’t really need or would use only occasionally.

73, Andy


Personally, I would never use BNC plugs in a Sota envirment where the cable is continually flexing causing the core to rupture where it joins to the center pin. Of this type, the TNC is a much better design.
I have been using sma plugs for hundreds of activations without failures and 100w cw.



Probably time everyone should be appraised of the half-century plus old technology behind the shrink tubing that shrinks on the outside, melts on the inside, creating the effect of perfectly “casting” whatever is in there. This technology was developed in the 1950’s at Stanford Research Institute. The principal investigator spun off to start Raychem (radiation chemistry). The primary technology was based on radiating polyolefin with an electron beam, thus cross-linking it, so that it could be heated above its normal melting point without melting. The tubing could then be stretched on a mandrill while hot, and allowed to cool at the larger diameter. When heated again, it tries to recover, “shrinking” around whatever’s there. Later, the same sort of tubing was “selectively-cross-linked” by controlling the intensity and time of the electron beam, such that the innermost part of the polyolefin was not cross-linked. This product was called SCL; when it was heated, the outside recovered, while the inside melted. There is no “glue”, just un-crosslinked material. Early shrink-tube listings by electronic distributors had a disclaimer statement that “the tubing had no residual radiation”, a dirty word, at the time!

Hope this clears up the “glue” thing. There is MUCH more to the Raychem story; look up Raychem history on the web.


I use BNCs all the time and in the main have suffered problems with the outer braid. Regular checks on leads are essential whatever connectors are used. I must admit to prefering soldered connections, but only because the connectors are likely to be salvageable. Must be down to doing too many activations in Scotland. :wink:

I do the same. Unfortunately, good BNC connectors for soldering have become rare, especially for RG 174.
In all the years it has happened to me twice that the rear screw connection has loosened and I had problems with the outer contact. But for that I have my Leatherman.
73 Armin