In article ,
says...


It's a commonly held view given that feeder losses are so much greater at
UHF, but it's wrong.

How about reading the manufacturers tables?
eg: URM43. 100MHz loss 13dB/100m
600MHz 34

URM67 50 MHz 4.5
800 MHz 18

Note sure if that adds anything... he just said that the feeder losses
are higher at UHF, but that does not necessarily mean that termination
losses are as well.

There are two issues here and it important to address them both. The
original, before it was selectively quoted, was:

In article ,
says...

It's a commonly held view given that feeder losses are so much greater
at UHF, but it's wrong.

Even if it's open circuit at DC there will still be a few picofarads
of capacitance, and capacitive reactance decreases as the frequency
increases.

The first part is very obviously wrong, as has been already been said.

The attenuation of any cable increases in a ratio of ~4:1 between channel B1
(or E2) and Channel E68.

However, if there is an open-circuit anywhere, part two comes into play.

On a broadband cable network with a continuous series of carriers the effect,
when viewed on an analyser, is startlingly clear!

Usually caused by the contractor (usually) who built the original network
failing to tighten the screw securing the centre conductor on a tap or
splitter ...


--

Terry

A quick calculation suggests that I have fitted at least 52,875 coax
plugs in my life, so far.

Bill

On Sat, 11 Jul 2015 20:18:23 +0100
Bill Wright wrote:

A quick calculation suggests that I have fitted at least 52,875 coax
plugs in my life, so far.

Bill

... which, if all laid end-to-end, would reach to ??

--
Davey.

Davey wrote:
On Sat, 11 Jul 2015 20:18:23 +0100
Bill Wright wrote:

A quick calculation suggests that I have fitted at least 52,875 coax
plugs in my life, so far.

Bill

.. which, if all laid end-to-end, would reach to ??

The mad house.

Bill

In article , Bill Wright
scribeth thus
A quick calculation suggests that I have fitted at least 52,875 coax
plugs in my life, so far.

Bill

Do you get a card from Prince Phil to tell you to get a fecking move on
to fit a few more;?...

As he is won't to do;!...
--
Tony Sayer

If the cable has a generous quantity of braid (as it should have) this wont
work because there is not room inside the body to accept both clamp and
braid.

The correct way - based on pictures provided by Belling & Lee 50 years ago
but recreated from memory - is as shown he

http://i260.photobucket.com/albums/i...oto/tv/BL1.png
http://i260.photobucket.com/albums/i...oto/tv/BL2.png
http://i260.photobucket.com/albums/i...oto/tv/BL3.png

It will probably be found easier to solder the centre pin first - this should
make it easier to trim the braid with flush bladed cutters.

The ring of braid compressed between the clamp and the insulator when the
plug is assembled provides a true coaxial termination.


Having misspent my younger years in the TV trade and having done quite a
bit of rigging..

The number of times I've seen a Belling Lee plug fitted like that as it
ought be around 10 or so. I swear blind those times were whilst I was
working at Pye TVT on some studio OB equipment.

The usual way was to wrap the braiding around the cable outer PVC and
then as long as there was enough to fill up the collet clamp part then
that was good enough.

I did ask the tight barsteward for a soldering iron so as to solder them
but he won't give us one and told us to nip the plug onto the inner core
of the co-ax with side cutters which wasn't ideal. Some people never
bothered with that even.

As to the soldered or not it did work surprisingly l well if it wasn't
soldered and it did work OK at UHF frequencies due to Capactive
reactance being more effective at those frequencies rather than at VHF
Band one and Three as there was never a strong ITV signal in the
Cambridge area..

IMHO life would have been better if Belling Lee had never invented the
damm thing anyway like the SCART plug and the abominable so called UHF
plug the PL259 used in some PMR applications.

In all the simple F plug was a much better idea.


--
Tony Sayer

In message , Bill Wright
writes
A quick calculation suggests that I have fitted at least 52,875 coax
plugs in my life, so far.

As they say, "Practice makes perfect".
--
Ian

On Sat, 11 Jul 2015 17:12:52 +0100, Terry Casey
wrote:

In article ,
says...


It's a commonly held view given that feeder losses are so much greater at
UHF, but it's wrong.

How about reading the manufacturers tables?
eg: URM43. 100MHz loss 13dB/100m
600MHz 34

URM67 50 MHz 4.5
800 MHz 18

Note sure if that adds anything... he just said that the feeder losses
are higher at UHF, but that does not necessarily mean that termination
losses are as well.

There are two issues here and it important to address them both. The
original, before it was selectively quoted, was:

In article ,
says...

It's a commonly held view given that feeder losses are so much greater
at UHF, but it's wrong.

Even if it's open circuit at DC there will still be a few picofarads
of capacitance, and capacitive reactance decreases as the frequency
increases.

The first part is very obviously wrong, as has been already been said.


I dont't think it is Terry, let me explain again.

I was replying to charles who said:
I'd expect far greater losses from an un-soldered joint at Band V


I replied

It's a commonly held view given that feeder losses are so much greater at
UHF, but it's wrong.

Apart from a missing comma after "view", I stand by what I said.

Surley my use of the word "given" shows that I conceed that the
statement that follows is true, ie cable losses are much higher at UHF
(than at VHF).

The point I was making is that an oxidised coaxial inner inserted into
a coaxial plug may well be open circuit as far as DC is concerned, but
the capacitor so formed (I would estimate 5-10pF) will, acording to
the equasion 1 / 2*pi*f*C, have progressivly lower Xc (expressed in
Ohms) as the frequency increases.

Such a termination will therefore contribute a fraction of the
attenuation at 500MHz than it would at 50MHz (to use my origanal
comparason between Band IV and Band I).

--

Graham.

%Profound_observation%

In article ,
says...

On Sat, 11 Jul 2015 17:12:52 +0100, Terry Casey
wrote:


The first part is very obviously wrong, as has been already been said.


I dont't think it is Terry, let me explain again.

I was replying to charles who said:
I'd expect far greater losses from an un-soldered joint at Band V


I replied

It's a commonly held view given that feeder losses are so much greater at
UHF, but it's wrong.

Apart from a missing comma after "view", I stand by what I said.

Surley my use of the word "given" shows that I conceed that the
statement that follows is true, ie cable losses are much higher at UHF
(than at VHF).

The point I was making is that an oxidised coaxial inner inserted into
a coaxial plug may well be open circuit as far as DC is concerned, but
the capacitor so formed (I would estimate 5-10pF) will, acording to
the equasion 1 / 2*pi*f*C, have progressivly lower Xc (expressed in
Ohms) as the frequency increases.

Such a termination will therefore contribute a fraction of the
attenuation at 500MHz than it would at 50MHz (to use my origanal
comparason between Band IV and Band I).

Fair enough but if I could misinterpret it then so could others, so a more
detailed explanation might help someone else who might more easily be
confused.

It certainly does no harm to spell it out in detail, particularly in uk.d-i-y
where the average reader will not be expected to have a good grasp of RF
theory and practice.

In uk.tech.digital-tv, where this thread also appears, I would expect a
better level of understanding in general, but it still isn't mandatory!


--

Terry

On 11/07/2015 17:12, Terry Casey wrote:
In article ,
says...


It's a commonly held view given that feeder losses are so much greater at
UHF, but it's wrong.

How about reading the manufacturers tables?
eg: URM43. 100MHz loss 13dB/100m
600MHz 34

URM67 50 MHz 4.5
800 MHz 18

Note sure if that adds anything... he just said that the feeder losses
are higher at UHF, but that does not necessarily mean that termination
losses are as well.

There are two issues here and it important to address them both. The
original, before it was selectively quoted, was:

In article ,
says...

It's a commonly held view given that feeder losses are so much greater
at UHF, but it's wrong.

Even if it's open circuit at DC there will still be a few picofarads
of capacitance, and capacitive reactance decreases as the frequency
increases.

The first part is very obviously wrong, as has been already been said.

Its not thought ;-) everyone keeps misreading it!

If one assembles the bits it effectively says:

"I'd expect far greater losses from an un-soldered joint at Band V"

To which Graham in effect replied:

"It's a commonly held view, but it's wrong."

What seems to have got everyone's knickers in a twist is the added comment

" *given* that feeder losses are so much greater at UHF,"

(my emphasis on "given") - i.e. he is acknowledging that the feeder
looses will be much higher, but this is a point unrelated to the effect
of frequency on poor connections (which will better "jump" small open
circuits due to the lower reactance of the capacitor formed)





--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 11/07/2015 20:55, tony sayer wrote:

IMHO life would have been better if Belling Lee had never invented the
damm thing anyway like the SCART plug and the abominable so called UHF
plug the PL259 used in some PMR applications.

In all the simple F plug was a much better idea.

I have seen loads of BL plugs with the inner unsoldered - but a length
of inner left protruding from the centre pin of the plug. In effect
making it behave somewhat like a F connector with the co-az itself doing
the final connection.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

En el artículo , Bill Wright
escribió:

A quick calculation suggests that I have fitted at least 52,875 coax
plugs in my life, so far.

I was impressed with the speed at which an aerial fitter fitted the
plug. Mind you, he had the proper tool for stripping the end of the
cable - it cut the outer insulation, the braid/foil, and the inner
insulation all to the right length in one go.

--
(\_/)
(='.'=)
(")_(")

On Mon, 13 Jul 2015 09:19:03 +0100
Mike Tomlinson wrote:

En el artÃ*culo , Bill Wright
escribió:

A quick calculation suggests that I have fitted at least 52,875 coax
plugs in my life, so far.

I was impressed with the speed at which an aerial fitter fitted the
plug. Mind you, he had the proper tool for stripping the end of the
cable - it cut the outer insulation, the braid/foil, and the inner
insulation all to the right length in one go.


Yeah, that's cheating. It's only valid if done with a blunt penknife.
This is, after all, a D-I-Y group.

--
Davey.

John Rumm wrote:

I have seen loads of BL plugs with the inner unsoldered - but a length
of inner left protruding from the centre pin of the plug. In effect
making it behave somewhat like a F connector with the co-az itself doing
the final connection.

That is often because the inner moves along the cable a bit, sometimes.
And it is unlikely that the protruding inner will contact the inner
connector of the socket, unless it is very bent.

Bill

Mike Tomlinson wrote:
En el artículo , Bill Wright
escribió:

A quick calculation suggests that I have fitted at least 52,875 coax
plugs in my life, so far.

I was impressed with the speed at which an aerial fitter fitted the
plug. Mind you, he had the proper tool for stripping the end of the
cable - it cut the outer insulation, the braid/foil, and the inner
insulation all to the right length in one go.


I would never do it like that. My coax plugs were lovingly hand-fitted.

Bill