What's this connector called? (SO239) - UK Vintage Radio Repair and Restoration Discussion Forum

Tractionist · 9th Jul 2021, 10:43 am

Hi All,

A friend has just bought a new transceiver [a 'Cobra] - and asked me what the aerial co-axial connector is called .... he needs to source a male section.

Off-hand I don't know. Photo attached.

HamishBoxer · 9th Jul 2021, 10:45 am

Amphenol . Easy to obtain from any amateur radio shop or Ebay.

ms660 · 9th Jul 2021, 10:47 am

Looks like a SO239, mates with a PL259.

EDIT: Post crossed.

Lawrence.

crackle · 9th Jul 2021, 11:02 am

Or can sometimes just simply be called a UHF female socket.
The male plug is a PL259 and you need to buy the correct type to fit the coax on the antenna lead in.
Mike

Tractionist · 9th Jul 2021, 12:45 pm

Cheers Guys! Many thanks [as usual] - saved me the research. Mods please close.

Radio Wrangler · 9th Jul 2021, 12:59 pm

It gets called many things. Some of them very rude!

It dates back to coax cables for connecting WWII radar gear.

It isn't really a 50 Ohm connector, it's not a controlled impedance type. At HF and lower VHF, this doesn't really matter. At UHF it does.

The method of connecting the braid to the outer of the mating PL259 plug is a right mess. With a lot of care and a big soldering iron it can be done, but many of the cheap plugs have solder-resistant plating! Some Japanese sourced males and females also have the wrong thread, just to bring a little excitement to the party. Close enough to mate, wrong enough to jam and gall (cold-weld)

THese things are so common on amateur radio gear, we're just stuck with them.

David

Skywave · 9th Jul 2021, 5:51 pm

When ever I meet the so-called 'UHF' plugs & sockets, I always replace then with N-types.

Al.

HamishBoxer · 9th Jul 2021, 6:16 pm

Did I use the wrong word ? If so I should have known PL259.

turretslug · 9th Jul 2021, 6:18 pm

I'm puzzled that it was as widely adopted as it was- perhaps the US amateur scene had loads available from surplus sources and the rest of the world understandably followed suit and it just stuck? I think of it as "shrouded banana plug"- OK maybe on bigger, older HF reception stuff but flawed for anything involving significant power and/or VHF/UHF and/or compactness- the device pictured ticking all three boxes. One of the various shortcomings I've encountered is that the outer securing ring needs to be done up really, really tight to stand any chance of a low-resistance connection with no guarantee of it staying that way. When I've occasionally encountered them on old test gear etc., I add a decent-quality converter to BNC, done up with pump pliers and left there.

Jon_G4MDC · 9th Jul 2021, 6:19 pm

Greenpar did PL259 with compression gland outer braid clamps, same as used on BNC and N.
For RG58 / RG223 cable. They were rather good but hard to find now.

9th Jul 2021, 6:41 pm

If I have one of these on a bit of kit I either replace it with a BNC or stick an adaptor to BNC on it.

BNCs are good for quite a lot of power (at least the UK 400W), cheap, easy to install, easy to plug/unplug, and smaller.

G6Tanuki · 9th Jul 2021, 6:42 pm

The "UHF" connector is really just a screened 4mm banana-plug: cheap and cheerful but not-that-good. Still, up to 150MHz or so it's probably better than the similar-design-era "Pye" coax-plug/socket.

The typical plugs sold to the amateur market - with holes in the barrel they expect you to solder-through to the braid - are useless: the plating doesn't readily take solder and you need a murderous soldering-iron to get enough heat into the barrel even once you've ground-away the plating to [hopefully] reveal brass underneath.

The compression-gland versions of these connectors are far easier to fit and cost only a few cents/pennies/Zlotys more.

CambridgeWorks · 9th Jul 2021, 6:53 pm

I have heard them called "wooden"!
Rob

Radio Wrangler · 9th Jul 2021, 6:54 pm

You do need to make sure you get the right version of the plug to suit the diameter of your coax. Typically they come in sizes for RG213 and RG58. There is also an adaptor sleeve to convert the larger to the smaller. For RG58 you're better with an adaptor and the RG213 plug! Better still are the compression versions )also 2 sizes.. but best of all is throwing the thing away and fitting an N connector.

SO239/PL259 connectors are notorious for coming loose as well.

N type compression connectors give some protection against water ingress.

David

dodgy-dxer · 10th Jul 2021, 7:38 am

Quote:

Originally Posted by Jon_G4MDC

Greenpar did PL259 with compression gland outer braid clamps, same as used on BNC and N.
For RG58 / RG223 cable. They were rather good but hard to find now.

Depends what you mean by "hard"?

https://ccsukltd.co.uk/coaxial-conne...ressure-Sleeve

Probably not Greenpar though

Fred

Jon_G4MDC · 10th Jul 2021, 8:43 am

Well done Fred! Not silver plated like Greenpar though are they?

emeritus · 10th Jul 2021, 12:31 pm

My first encounter with these connectors was as a student. They were used on the old Tektronix oscilloscopes for connecting the scope probes.

Interesting comment about Japanese versions having a different thread. I have had a similar experience with the threads for microphone stands, which I think use the same diameter and pitch, where some fittings bought from Maplin have had a metric pitch that engages, but binds after a couple of turns.

winston_1 · 10th Jul 2021, 2:38 pm

They were (are) known as F & E connectors at the BBC.

barrymagrec · 10th Jul 2021, 5:09 pm

Quote:

Originally Posted by winston_1

They were (are) known as F & E connectors at the BBC.

I`m surprised by that, I always thought that F & E`s (Films and Equipment) were the old large 3 pin microphone connectors, similar to the Cannon EP type.

dodgy-dxer · 10th Jul 2021, 5:35 pm

Quote:

Originally Posted by Jon_G4MDC

Well done Fred! Not silver plated like Greenpar though are they?

Nope and 2B stores is out of stock (out of business too) these days

CCS is a good reliable supplier

Hope you are well

Fred

9th Jul 2021, 10:43 am	#1
Tractionist Heptode Join Date: Apr 2016 Location: Cheltenham, Gloucestershire, UK. Posts: 875	What's this connector called? (SO239) Hi All, A friend has just bought a new transceiver [a 'Cobra] - and asked me what the aerial co-axial connector is called .... he needs to source a male section. Off-hand I don't know. Photo attached. Attached Thumbnails __________________ Red to red, black to black. Throw the switch and stand well back!

9th Jul 2021, 10:45 am	#2
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: What's this connector called? Amphenol . Easy to obtain from any amateur radio shop or Ebay. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

9th Jul 2021, 10:47 am	#3
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: What's this connector called? Looks like a SO239, mates with a PL259. EDIT: Post crossed. Lawrence.

9th Jul 2021, 11:02 am	#4
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: What's this connector called? Or can sometimes just simply be called a UHF female socket. The male plug is a PL259 and you need to buy the correct type to fit the coax on the antenna lead in. Mike

9th Jul 2021, 12:45 pm	#5
Tractionist Heptode Join Date: Apr 2016 Location: Cheltenham, Gloucestershire, UK. Posts: 875	Re: What's this connector called? Cheers Guys! Many thanks [as usual] - saved me the research. Mods please close. __________________ Red to red, black to black. Throw the switch and stand well back!

9th Jul 2021, 12:59 pm	#6
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,876	Re: What's this connector called? It gets called many things. Some of them very rude! It dates back to coax cables for connecting WWII radar gear. It isn't really a 50 Ohm connector, it's not a controlled impedance type. At HF and lower VHF, this doesn't really matter. At UHF it does. The method of connecting the braid to the outer of the mating PL259 plug is a right mess. With a lot of care and a big soldering iron it can be done, but many of the cheap plugs have solder-resistant plating! Some Japanese sourced males and females also have the wrong thread, just to bring a little excitement to the party. Close enough to mate, wrong enough to jam and gall (cold-weld) THese things are so common on amateur radio gear, we're just stuck with them. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

9th Jul 2021, 5:51 pm	#7
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: What's this connector called? When ever I meet the so-called 'UHF' plugs & sockets, I always replace then with N-types. Al.

9th Jul 2021, 6:16 pm	#8
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: What's this connector called? Did I use the wrong word ? If so I should have known PL259. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

9th Jul 2021, 6:18 pm	#9
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,396	Re: What's this connector called? I'm puzzled that it was as widely adopted as it was- perhaps the US amateur scene had loads available from surplus sources and the rest of the world understandably followed suit and it just stuck? I think of it as "shrouded banana plug"- OK maybe on bigger, older HF reception stuff but flawed for anything involving significant power and/or VHF/UHF and/or compactness- the device pictured ticking all three boxes. One of the various shortcomings I've encountered is that the outer securing ring needs to be done up really, really tight to stand any chance of a low-resistance connection with no guarantee of it staying that way. When I've occasionally encountered them on old test gear etc., I add a decent-quality converter to BNC, done up with pump pliers and left there.

9th Jul 2021, 6:19 pm	#10
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: What's this connector called? Greenpar did PL259 with compression gland outer braid clamps, same as used on BNC and N. For RG58 / RG223 cable. They were rather good but hard to find now.

9th Jul 2021, 6:41 pm	#11
Guest Guest Posts: n/a	Re: What's this connector called? If I have one of these on a bit of kit I either replace it with a BNC or stick an adaptor to BNC on it. BNCs are good for quite a lot of power (at least the UK 400W), cheap, easy to install, easy to plug/unplug, and smaller.

9th Jul 2021, 6:42 pm	#12
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: What's this connector called? The "UHF" connector is really just a screened 4mm banana-plug: cheap and cheerful but not-that-good. Still, up to 150MHz or so it's probably better than the similar-design-era "Pye" coax-plug/socket. The typical plugs sold to the amateur market - with holes in the barrel they expect you to solder-through to the braid - are useless: the plating doesn't readily take solder and you need a murderous soldering-iron to get enough heat into the barrel even once you've ground-away the plating to [hopefully] reveal brass underneath. The compression-gland versions of these connectors are far easier to fit and cost only a few cents/pennies/Zlotys more.

9th Jul 2021, 6:53 pm	#13
CambridgeWorks Nonode Join Date: Jun 2010 Location: Spalding, Peterborough, Cambridgeshire, UK. Posts: 2,859	Re: What's this connector called? I have heard them called "wooden"! Rob __________________ Apprehension creeping like a tube train up your spine - Cymbaline. Film More soundtrack - Pink Floyd

9th Jul 2021, 6:54 pm	#14
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,876	Re: What's this connector called? You do need to make sure you get the right version of the plug to suit the diameter of your coax. Typically they come in sizes for RG213 and RG58. There is also an adaptor sleeve to convert the larger to the smaller. For RG58 you're better with an adaptor and the RG213 plug! Better still are the compression versions )also 2 sizes.. but best of all is throwing the thing away and fitting an N connector. SO239/PL259 connectors are notorious for coming loose as well. N type compression connectors give some protection against water ingress. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

10th Jul 2021, 8:43 am	#16
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: What's this connector called? Well done Fred! Not silver plated like Greenpar though are they?

10th Jul 2021, 12:31 pm	#17
emeritus Dekatron Join Date: Jan 2012 Location: Brentwood, Essex, UK. Posts: 5,339	Re: What's this connector called? My first encounter with these connectors was as a student. They were used on the old Tektronix oscilloscopes for connecting the scope probes. Interesting comment about Japanese versions having a different thread. I have had a similar experience with the threads for microphone stands, which I think use the same diameter and pitch, where some fittings bought from Maplin have had a metric pitch that engages, but binds after a couple of turns.

10th Jul 2021, 2:38 pm	#18
winston_1 Hexode Join Date: Oct 2012 Location: London, UK. Posts: 498	Re: What's this connector called? They were (are) known as F & E connectors at the BBC.