Odd co-ax connector

[ppppenguin]

I've found a few of these co-ax connectors. They will mate with standard Belling-Lee aerial connectors though the weight of a plug might be unkind to an ordinary B&L socket.

Are they a special by Taylor? I think I've seen them eslewhere on aerial amplifiers but not sure. They are nicely made in heavy brass but the inner moulding and cable grip look the same as a standard B&L. Though they do have much better support for the cable.

The photo shows a couple of plugs, a 75R termination and an attenuator.

I can't see any advantage over F connectors. They are obviously a lot heavier and more expensive than F. I also can't see that they will be electrically better than F, either for contact or at high frequencies.

Does anyone know anything about them? Need any of them?

[Mike Watterson]

I think the Belling Lee used as a TV connector was acceptable for Band I. It was originally for AM radio! A good F-connector and cable is OK to 2.5 GHz.
Some F-Connectors are very good, others poor. I have some F-socket -> B&L adaptors which save messing about trying to make up a Belling-Lee plug. I have crimp F types that don't crush the dielectric and are nearly waterproof for regular double screened cable and also for the lower loss fatter cable that can be buried. Next size up is main trunk which we only used on huts to masts with 75 Ohm version of N-type. The 10.5 GHz band transceiver is fed with a cable broadband CMTS. The client location has a smaller transceiver using regular RG6/CT100 etc style cable to an indoor cable modem. Mines been running on a near 14km path with 8 Mbps down / 1Mbps up since December 2005. I experimented with SD and HD H.264 channels using DVB-c on the link in a lab using a plug in PCI PC card to generate the DVB-c from a looped file of MPEG-2. That was a 6MHz channel. We also experimented on the 900MHz band using our allocated channels using DOCSIS and and DVB-c on a 2MHz channel with the IF filters swapped. Then the 2008 Bank Crisis hit and all the R&D ceased.

[ppppenguin]

The B&L connector has been used successfully up to Band V (800MHz or so) but it's hardly ideal. That's putting it politely. It's also tricky to fit properly. Notably the inner should be soldered and frequently isn't. Also it's not quick or easy to get a good conenction to the screen. Some of the B&L extension leads with moulded plugs are awful.

This screw on version of the B&L strikes me as a misguided way to improve a poor design. Why bother when the F conenctor is much cheaper and smaller. I think they will end up in my pile of scrap brass for next time I go to the scrap metal merchant.

[Mike Watterson]

I suppose it depends on the definition of success. OTH the "low loss coax" that was traditionally sold for UHF before satellite cable (LNB IF) was common is probably a nice leaky feeder for local UHF broadcasting in a tunnel or shielded room.

Indeed I've used the "spiderweb" coax and BL connectors for a while for TG4 channel 68. Ages ago.

Everything here 75 Ohms is now F-connector with adaptors on the few DVB-T tuners with BL sockets.

[ppppenguin]

Success, as in used on just about every UK TV from the early 1950s to the present day. Low loss "leaky feeder" had braid coverage that varied from moderate to negligible. Both connector and cable still worked adequately in the vast majority of domestic installations. Add in horrible unscreened amplifiers (I've just come across one of those (Labgear?) masthead amps a circular plastic case) and splitters and it's wonder we got TV working at all.

The late and much missed Terry Casey insisted on using F connectors and CT100 class cable throughout the TV distribution system at the Dulwich Museum. Only adapting to B&L or other connectors to feed the individual TVs. Quite right too.