Continuing the Television theme …

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Continuing the Television theme …

Home Forums Electronics in the Workshop Continuing the Television theme …

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  • #786921
    Michael Gilligan
    Participant
      @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.

      .

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

      IMG_0653

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      #786932
      bernard towers
      Participant
        @bernardtowers37738

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

        #786935
        peter1972
        Participant
          @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

          #786943
          Michael Gilligan
          Participant
            @michaelgilligan61133
            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.

             

            #786953
            SillyOldDuffer
            Moderator
              @sillyoldduffer

              Yer tis’

              Screenshot From 2025-03-02 19-23-53

              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

              #786960
              Mark Rand
              Participant
                @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…

                #786964
                Robert Atkinson 2
                Participant
                  @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.

                  #786991
                  SillyOldDuffer
                  Moderator
                    @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:

                    wireless-set-19-variometer-1-3-1000x1000

                    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

                     

                     

                     

                     

                    #786995
                    Michael Gilligan
                    Participant
                      @michaelgilligan61133
                      On SillyOldDuffer Said:

                      Yer tis’

                      Screenshot From 2025-03-02 19-23-53

                      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

                      On SillyOldDuffer Said:

                      Yer tis’

                      Screenshot From 2025-03-02 19-23-53

                      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

                      Many thanks for the drawings, Dave !

                      … and for your offer of some sample measurements.

                      MichaelG.

                      .

                      Edit: __ This is an earlier model of LG TV … but I am taking it as circumstantial evidence of their build-quality:

                      #787005
                      Michael Gilligan
                      Participant
                        @michaelgilligan61133

                        In my present enfeebled state, I dare not risk taking the TV off its shelf, but I’ve managed to get a snapshot of the female connector … confirming Dave’s assumption:

                        .

                        IMG_0250

                        .

                        MichaelG.

                        #787043
                        SillyOldDuffer
                        Moderator
                          @sillyoldduffer

                          As promised some measurements.   I’m surprised!

                          Be warned: don’t read this if you like to believe British made stuff from yesteryear is high-quality compared with modern rubbish!

                          Here are the examples:

                          1. 1950/60 British.

                          DSC06885

                          2.  Modern plastic, circa 2000.

                          DSC06886

                          3.  1970-ish British, Aluminium, very common (2 examples):

                          DSC06887

                          4.  Metal recent, foreign made:

                          DSC06888

                          In general these are not precision made!  The pins and bodies are not round, and sizes vary considerably on the same plug and in comparison with others.

                          1950’s British, with silver plate.   Body 9.32, 9.46, 9.40, 9.55, variance 0.23mm.   Pin 2.40mm

                          1970’s Aluminium.  British. Corroding.

                          • Example 1: Body 9.54, 9.59, 9.55, 9.52 variance 0.07mm.  Pin 2.35, 2.33, 2.32, 2.37 variance 0.05mm.  Crudely threaded, hard to assemble
                          • Example 2: Body 9.46, 9.45, 9.47, 9.46 variance 0.02mm.  Pin 2.49, 2.35, 2.41, 2.37, variance 0.14.  Clean thread,

                          Plastic Modern circa 2000:  Body 9.53, 9.56, 9.54, 9.47 variance 0.09mm.  Pin: 2.37

                          Metal Modern, recent purchase:  Body 9.49, 9.48, 9.47. 9.50, variance 0.03mm  Pin: 2.36, 2.26, 2.25, 2.26 variance 0.01mm

                          These plugs aren’t made to high tolerances!  Though they look similar one British Aluminium plug is more accurately made than the other.

                          And although the silver-plated plug looks good, it’s dimensionally poor compared with the Aluminium plugs.  The plastic modern plug is slightly worse than them, but the best is the recent purchase.

                          Body dia should be 9.525mm.  Mine are mostly under that, except for a couple of fat spots, probably due the body not being round.

                          Pin should be 2.35mm.  Again, my examples are mostly undersized, with a few fatties.

                          Conclusion:   with one exception, possibly lucky, my sample plugs clearly aren’t precision made!  Therefore expect some loose and some excessively tight fits.   I guess Michael’s TV has a sprung tight socket, and his plugs are all fatties apart from the Maxviews.  I must have used hundreds of Belling Lee plugs over the years and not had a problem, but…

                          Dave

                           

                           

                           

                          #787058
                          John Haine
                          Participant
                            @johnhaine32865

                            The horrible Balling Lee coax connector seems a British thing.  I notice that the LG TV pictured has what I think is an F-type connector for a satellite input next to the Belling Lee.  I’ve had an FM/DAB tuner that also had an F-type.  Time the BL connector was consigned to the dustbin of history as the F types must be pretty cheap.

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