Continuing the Television theme …

[Michael GilliganParticipant @michaelgilligan61133]

I have just spent a very frustrating afternoon doing a five-minute job !

When I moved to North Wales, I just plonked the LG television on a convenient shelf, and didn’t bother installing it.

A couple of weeks back, I tried plugging a shiny new coax antenna-lead into the socket … “oh deary me” says I [or words to that effect], the plug doesn’t fit the socket and it feels like I will break the circuit board !

Returning this afternoon with an assortment of leads gathered from my hoard [the original, of course, having been left in-situ at the old house] … not one of the plugs fits the TV !

As luck would have it … I also had a ‘Trade Pack’ of loose plugs from MAXVIEW and Yes these fit beautifully.

 

So … my question for the forum is: Is there a dimensional standard for these plugs and sockets, and if so, how tightly toleranced is it ???

I rather suspect that some evil ‘rounding’ has crept-in with metrication

MichaelG.

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Edit: __ For the benefit of anyone else hitting the same problem:

[bernard towersParticipant @bernardtowers37738]

Smacks of lets make this a bit different and they will have to buy from us

[peter1972Participant @peter1972]

The plug diameter should be 3⁄8-inch (9.525mm). I have not found what the diameter the inner pin should be.

https://en.wikipedia.org/wiki/Belling-Lee_connector

[peter1972]

On peter1972 Said:

The plug diameter should be 3⁄8-inch (9.525mm). I have not found what the diameter the inner pin should be.

https://en.wikipedia.org/wiki/Belling-Lee_connector

Thanks, Peter … I will measure the two inner pins tomorrow

[need to dissect the non-fitting one]

MichaelG.

 

[SillyOldDufferModerator @sillyoldduffer]

Yer tis’

I’ve got loads of them, so will measure a few.  Quality varies enormously.   The LG problem might be the female – they’re spring-loaded in various ways to grip the plug, ranging from cheap and nasty slots to elaborate clips.   Possibly the LG has a strong spring and needs a lot force to open it.  The chamfer on the plug that opens it isn’t specified…

Why is nothing ever easy?

Dave

[Mark RandParticipant @markrand96270]

It’s a real shame that tellies and wirelesses didn’t standardise on 75Ω BNC connectors instead of the weird rather non-conductive aluminium VHF connectors. Of course, having said that, I had problems with silver plated BNCs in coal fired power stations. Silver sulfide is a lousy conductor at mV levels…

[Robert Atkinson 2Participant @robertatkinson2]

BNC’s were orders of magnitude more expensive than the “Belling Lee” in the 50’s and 60’s when TV’s first became popular. No contest for a cost sensitive market.

[SillyOldDufferModerator @sillyoldduffer]

I much prefer BNC too, though 50 rather than 75Ω.   (There is an engineering reason.)

The Belling Lee connector has many virtues though as a consumer plug/socket that’s not continually being pulled in and out.   They’re cheap, easy to wire, reasonably robust, and perform acceptably up to about 1GHz.   And if a radio ham uses one to transmit power, they’ll handle up to about 150W without melting!

BNC provide a secure lock and support repeated disconnects, have better RF performance, often silver-plated, but are pricey and harder to wire.  Back in the day BNC was very expensive compared with Belling Lee, not so bad now.

I’ve not much experience of them, but F-connectors seem a good consumer compromise: cheaper than BNC and more secure than Belling Lee.   None of my equipment has an F-socket!

Worst of all in my experience are the PL259/SO259 range.   Allegedly UHF, but not good and they’re difficult to wire, including fun and games with the reducers needed to take different diameter coaxes.  Main virtue is a well-made one will handle a kilowatt of RF.  Unfortunately many of them are cheap and nasty.

Looking up Belling Lee to find the dimensions revealed several oddities!  It’s claimed the connector was invented in 1922 which is odd because Americans believe they invented coaxial cable in 1931!  If 1922 is real, rather than a typo for 1932 or 1942, then what cable did Belling Lee’s plug/socket connect?  Coaxial cable existed in the 19th century, say 1860, but only in rigid form – a central wire spaced inside a rigid copper pipe, not flexible as we’re used to.  Flexible only became practical  with plastics developed in the 1930 and 40s.   So what cable did Belling Lee use in 1922?  Whatever it was, only expected to work up to 1.6MHz (Medium Wave radio), so the plug working up to 1GHz is a triumph!  Americans also believe we call it a PAL connector: maybe on the continent, but never heard it called that in the UK.

As an aside, does anyone know what the coax connectors used by the UK military during WW2 are?   Sockets very common on surplus equipment, but plugs were hard to find.   Like this example on a 19 Set Variometer:

UK WW2 coax connectors disappeared fairly quickly after the war.  Maybe they weren’t very good, or possibly, it was realised standardisation was important: all NATO equipment should take the same cables, so a US cable could be used to connect a UK radio and vice-versa.

Dave

 

 

 

 

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