On 19/08/17 16:25, Rambo wrote:
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.


That short attention span probably contributes to your problems studying
and acquiring technical knowledge. That accounts for your problems with
the Advanced Exam and lack of other qualifications.

You should really have tried to seek help earlier, you could perhaps
have improved it and achieved at least some worthwhile qualifications.