XPost: uk.radio.amateur   
   From: no.sp@m.com   
      
   On 19/08/17 13:05, Ian Jackson wrote:   
   > In message , Gareth's Downstairs Computer   
   >  writes   
   >> On 19/08/2017 10:34, Jimbo wrote:   
   >>>> sexes).   
   >>>    when I was newly licensed and poor I used 75 ohm TV coax and   
   >>> belling lee   
   >>> connectors on HF and got away with it .......   
   >>>   
   >>   
   >> And it was standard on 145MHz. (QQV03-10 anyone?)   
   >   
   > Actually, the original B&L connector is a pretty good 75 ohm match up to   
   > 1GHz and more. If I remember correctly, many 50 ohm BNCs are not so hot   
   >  >500MHz. With 75 ohms, the problem is maintaining the structural return   
   > loss constant while having enough PTFE insulation to hold the pin in   
   > place. Some are only really good to around 200Mhz. Of course, for most   
   > purposes, both are usable to much higher frequencies.   
   >   
   > And mixable!   
      
   Well, the B&L connectors are used for TV which covers well into the 100s   
   of MHz. There is also the F connector, another 'cheap and cheerful'   
   beast, used beyond 1GHz. I've not done any measurements but it obviously   
   performs were enough for the task demanded of it.   
      
   Both the B&L and F connector suffer (as do all connectors) problems if   
   not fitted correctly but they are more  prone to being 'bodged'. The B&L   
   is, for example. prone to issues with poor braid bonding while the F   
   connector, which uses the centre conductor as the pin, tend to be prone   
   to the 'pin' not aligning etc. I believe the F connector is used in the   
   US where we would, generally, expect to see a B&L connector. I believe   
   the B&L is virtually unknown in the US. I was contacted by a US amateur   
   some time back who had acquired a bit of UK kit (KW?) which had B&L   
   sockets. He'd not seen them before. I sent him some plugs etc.   
      
   Of course, there is nothing 'magic' about 50 ohm coax or the connectors   
   we 'normally' use on our radios. If we were to stick to using 75 ohm   
   coax and B&L connectors the world wouldn't end. Likewise, if you mixed   
   50 ohm and 75 ohm, while you may be able to measure a slight difference,   
   chances are, in real terms, it wouldn't make much difference to the   
   overall set up performance- at least unless you were doing something   
   'exotic'. You'd be more likely to notice the impact of a poorly fitted   
   'correct' connector in an all 50 ohm system.   
      
   I tend to favour N types but I've not change all the connectors on my   
   radios. The 'first' patch lead as whatever the radio needs on one end   
   and required N type to connect to rest on the station on the other. The   
   same for my mobile set ups.   
      
   I also have a good collect of, quality, interseries, adaptors etc and a   
   set of the correct connectors for my Bird power meters and dummy load   
   etc. Through in a few home brew special adaptor leads for things I don't   
   have adaptors for and I can interconnect virtually anything.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)