XPost: uk.radio.amateur   
   From: Rambo@thisaintreal.org   
      
   On Sat, 19 Aug 2017 15:22:26 +0100, Brian Reay  wrote:   
      
   >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.   
   >   
   >   
   >   
   >   
   Oh! has he finished? I dozed off for a moment there.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)