[time-nuts] OT: Re: TNC connectors

Dave Baxter dave at uk-ar.co.uk
Tue Jun 23 12:49:37 EDT 2009


Chuck, please realise we're in the UK, not the US, so things are significantly different in many ways...

"TV coax" hear is really cheap cruddy stuff, if you're very lucky you might get 50% braid/shielding coverage!   There was no real need to prevent ingress or egress of signals, as (other than channel 36 around some airports) that band was dedicated to broadcast TV.

Unlike in the US, where your cable distribution systems had to be buttoned up quite well, as the same frequencies are also used over the air for "other services" etc.  

The "Satellite LNB" coax that you regard as "standard TV coax", has only recently become common over here, since the rise in popularity of Satellite TV, and the need to use good quality cable, as well as keeping stuff in or out as needed.

Yes, I'm aware of the old "AM" car radio aerial cable.  But from what I've seen (still got in places) that was a very poor imitation of the 93r coax we used for the network.  Almost no braid, and the very thin "wire" (much thinner than in the network cable) just floating about in the tube dielectric, no spiral filament to hold it in the centre.  But it was no doubt cheap to produce.  (That reminds me, I need a replacement broadcast antenna for the 4x4, the last one argued with a tree, and lost, not as rugged as advertised!)

Metric vs Imperial:   Wasn't the USA supposed to go Metric decades ago?  Many instrument makers managed it (IBM, HP, TEK etc.)  But the folklore I remember when I was in the US just down 101 from San Jose back in the early 90's, states that most small (jobbing) metal bashing suppliers just plain refused to push the "Metric" button on their CNC machines  ;-)    Certainly, the ones we used would and could do metric if you really wanted, but they didn't half grumble about it...  (They did a good job though!)

Non standard connectors, yes, it happens.  BT in this context is British Telecom, and I guess they could have had connectors made especially for them.  But I've also seen the same things on Ex BBC broadcast and other kit.   Closely allied to BT or the GPO as it used to be it has to be said, so no surprise there I guess.  In either case, I suspect it effectively became a "Standard" over hear within that industry.

"Metric UHF connector threads".  Yep, whatever the thread is supposed to be, there are many variations on that theme (and also the exact size of the centre pin!)  Another reason I avoid them like the plague!.  Not least their tendency to explode in flames with a kilowatt flowing through them!  There again, I've also destroyed good clean N connectors with less RF than that.  (Bad VSWR problems!)

"Radio Shack" never existed in the UK.  There was a brief period where "Tandy" was on the high street, with Rat Shack branded products.  "RS" over hear stands for what used to be "Radio Spares".  Now RS Components, one of the big (huge) catalogue based component suppliers, like your Mouser or DigiKey (who are also over hear in a small but expensive way.)

Even then, Tandy went for the "Gadget" toy and phone market, abandoning even the small line of components they had, their products were of doubtful quality as well from what I remember.   The closest now in the UK would be Maplin, though they are slowly moving away from components, towards toys, gadgets, PC's and phones etc.  Go in to there and start asking for TNC connectors, and you'll probably get a blank stare...

What you call RCA connectors, we call "Phono" connectors.  Another example.

Interestingly, Maplin do this...
http://www.maplin.co.uk/Module.aspx?ModuleNo=1587&C=SO&U=strat15

A TNC Male, to BNC Female adapter.  For the impressive cost of £1.89  Useful to know.   Now all you have to do, is find a store with one in stock, and what the "Quality" is like is anyone's guess at that price.

Pipe threads and mounting poles...   We can't just go to "Any US plumbing supply store".  There are DIY equivalent stores here of course, but you'd be very lucky indeed to find any iron water piping for domestic use these days.  Threaded or otherwise!  Even our water plumbing (Hot as well as cold) is moving towards plastic and push fit fittings.  (!)

Again, please be aware we are not in the USA, and 90+% of all our suppliers are exclusively metric, so it can be an issue to get the "correct stuff", when it is critical, and it is some odd (to us) imperial size or thread fitting..

Strangely, the more common it is in the US, the scarcer it is over hear it seems.  Bit like trying to by Tea bags and Branston Pickle in the US.  Not to say a decent electric kettle!  :-)

'Nuff said I think.

Regards to all.

Dave B.





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