"The Natural Philosopher" wrote in message
...
On 24/05/16 13:13, maurice wrote:
"The Natural Philosopher" wrote in message
...
On 24/05/16 12:41, maurice wrote:
"The Natural Philosopher" wrote in message
...
..

A quarter wave monopole is always 36 ohms. End of discussion

"Since a half-wave dipole has a gain of 2.19 dBi and a radiation
resistance of 73
ohms,
a quarter-wave monopole, the most common type, will have a gain of
2.19 + 3 = 5.19
dBi
and a radiation resistance of about 36.8 ohms if it is mounted above a
good ground
plane.[1]"

https://en.wikipedia.org/wiki/Monopole_antenna

It looks like a 5 year old Turnip must have been at home sick, on the
day
the teacher chalked the word "if" on the blackboard.


If it isnt, it still wont be 50 ohms

It looks as if he was also off sick on the day the teacher chalked up
"is always"
and "If it isn't" on the board, and asked the children if both could be
true at the
same time.

A very sickly child, by the looks of things.


michael adams


I assume you are of the Left persuasion, as this all out ad hominem
continues?

Of course we never ever see any ad hominem from you.

You do realise how unpleasant and stupid you are appearing?

Oh, the irony.

On 23/05/2016 19:50, Johnny B Good wrote:
These days there's no compelling case for specifying Fast over Gbit
ethernet switches on cost grounds, especially as entry level Desktop PCs
and proper Notebooks have been equipped with Gbit lan ports as standard
fit for the past 5 years or more.

For many, I agree. But after the first wave of "of course it's gigabit"
machines came out, there was a period in which a considerable number of
machines reverted to Fast. Was somewhat surprised how many I saw.

--
Rod

In message , News
writes
In message , Andy Burns
writes

Yes, as far as home switches are concerned, they're plug and forget.
You could push the boat out and get a gigabit one for a couple of quid
more.

OK, thanks to you both (Mike and Andy). Point taken, and D-Link 5-Port
Gigabit Switch ordered through ebuyer

Job done! Thanks all. The switch arrived, was connected and it just
works. Delighted. That has kept Son happy, and cost me a fiver.

--
Graeme

En el artículo , News
escribió:

Job done! Thanks all. The switch arrived, was connected and it just
works. Delighted. That has kept Son happy, and cost me a fiver.

Are you sure you got a gigabit one? The D-Link one closest to 5 quid
(QuickFind: 351558) is 10/100 only.

You would have been better paying a little more for the TP-Link gig
switch at 13 quid IMO. QuickFind: 721574

--
(\_/)
(='.'=) Windows 10: less of an OS, more of a drive-by mugging.
(")_(") -- "Esme" on el Reg

In message , Mike Tomlinson
writes
En el artículo , News
escribió:

Job done! Thanks all. The switch arrived, was connected and it just
works. Delighted. That has kept Son happy, and cost me a fiver.

Are you sure you got a gigabit one? The D-Link one closest to 5 quid
(QuickFind: 351558) is 10/100 only.

Sorry Mike! Yes, you're quite right - I looked at the wrong figure on
the invoice. What I bought was 9.15 plus VAT, so just under 11 pounds.

It is a 'D-Link GO-SW-5G - GO 5-Port Gigabit Switch', now showing on
ebuyer as out of stock.

I never normally think about ebuyer, and only used this time because I
followed a recommendation posted in another thread.

--
Graeme

En el artículo , News
escribió:

Sorry Mike! Yes, you're quite right - I looked at the wrong figure on
the invoice. What I bought was 9.15 plus VAT, so just under 11 pounds.

Think you did well there Glad it does the job for you. It really
would have been silly saving a couple of quid to get a slower 10/100
one. You'll never regret getting a gig switch, especially if you start
streaming movies or flinging large files around.

I never normally think about ebuyer, and only used this time because I
followed a recommendation posted in another thread.

Yes, that's the Dremel-type tool and kit I posted a link to a while
back. Is it any good?

cheers

--
(\_/)
(='.'=) Windows 10: less of an OS, more of a drive-by mugging.
(")_(") -- "Esme" on el Reg

In message , Mike Tomlinson
writes
En el artículo , News
escribió:

Sorry Mike! Yes, you're quite right - I looked at the wrong figure on
the invoice. What I bought was 9.15 plus VAT, so just under 11 pounds.

Think you did well there Glad it does the job for you. It really
would have been silly saving a couple of quid to get a slower 10/100
one. You'll never regret getting a gig switch, especially if you start
streaming movies or flinging large files around.

Indeed. The switch is used by son, so he can connect PC, Xbox and
Playstation. I monitor our usage regularly, and it is amazing how it
plummets whenever he is away. How he manages, I don't know. We (self
and wifey) watch movies and stuff, wifey plays online games yet our
usage seems minimal.

I never normally think about ebuyer, and only used this time because I
followed a recommendation posted in another thread.

Yes, that's the Dremel-type tool and kit I posted a link to a while
back. Is it any good?

Well, it looks excellent. Haven't used it in anger yet, but will report
back, when I do.
--
Graeme

On Wed, 25 May 2016 04:59:25 +1000, "9pl" wrote:



"The Natural Philosopher" wrote in message
...
On 24/05/16 13:13, maurice wrote:
"The Natural Philosopher" wrote in message
...
On 24/05/16 12:41, maurice wrote:
"The Natural Philosopher" wrote in message
...
..

A quarter wave monopole is always 36 ohms. End of discussion

"Since a half-wave dipole has a gain of 2.19 dBi and a radiation
resistance of 73
ohms,
a quarter-wave monopole, the most common type, will have a gain of
2.19 + 3 = 5.19
dBi
and a radiation resistance of about 36.8 ohms if it is mounted above a
good ground
plane.[1]"

https://en.wikipedia.org/wiki/Monopole_antenna

It looks like a 5 year old Turnip must have been at home sick, on the
day
the teacher chalked the word "if" on the blackboard.


If it isnt, it still wont be 50 ohms

It looks as if he was also off sick on the day the teacher chalked up
"is always"
and "If it isn't" on the board, and asked the children if both could be
true at the
same time.

A very sickly child, by the looks of things.


michael adams


I assume you are of the Left persuasion, as this all out ad hominem
continues?

Of course we never ever see any ad hominem from you.

You do realise how unpleasant and stupid you are appearing?

Oh, the irony.

+1

Cheers, T i m

Chuck em for scrap. even the cable at 50 ohms is no good for TV/VHF
radio.

really?

Well not for an antenna anyway.

Most RF work is done at 75ohms or 300 ohms for reasons to do with the
permittivity of free space or summat. Mr Sayer might know more

50 ohms is very much the 'lab standard for RF/video kit that never gets
to see an aerial'..


a great many professional aerials (or should I say antennae?) are of 50ohm
impedance.

Unlikely. Not at the raw antenna level. You HAVE to match using some
kind of extra circuitry for any other impedance than 75 ohm (quarter
wave) or 300 ohm (half wave).



All pro two-way radio broadcast TV and VHF FM & DAB are 50 ohms as are
the cable connectors, transmitter outputs etc. Most all using dipoles as
the radiating elements have a "BALUN" BALance to UN Balance transformer.

Some use Gamma or Delta matches but the idea is the same to match the
balanced dipole to the un balanced co-axial cables except those
occasions where LF MF and HF arrays are used.

Quite a complex subject overall!....
--
Tony Sayer

In article ,
scribeth thus
On Monday, 23 May 2016 22:12:31 UTC+1, The Natural Philosopher wrote:
On 23/05/16 18:48, wrote:
On Monday, 23 May 2016 18:30:41 UTC+1, The Natural Philosopher wrote:

a great many professional aerials (or should I say antennae?) are of 50ohm
impedance.

Unlikely. Not at the raw antenna level. You HAVE to match using some
kind of extra circuitry for any other impedance than 75 ohm (quarter
wave) or 300 ohm (half wave).

Quarter-wave monopoles can be made to give an excellent match to 50 ohms
without needing any extra matching components.


You may think there are no (extra components) , but there are.

Even if they look like twisted bits of wire..

That might be a loading coil...

There is no need for any twisted bits of wire to make a quarter-wave monopole
with a 50 ohm impedance at resonance.

John

Well your average Taxi will have a straight rod "somewhere" around a
quarter wave; thats matched via it being the right length to a 50 Ohm
feeder cable to the 50 Ohm transceiver.

But its going the way of the dodo these days a lot are now using
smartfone apps over cellular networks....
--
Tony Sayer

On 28/05/16 11:46, tony sayer wrote:

Chuck em for scrap. even the cable at 50 ohms is no good for TV/VHF
radio.

really?

Well not for an antenna anyway.

Most RF work is done at 75ohms or 300 ohms for reasons to do with the
permittivity of free space or summat. Mr Sayer might know more

50 ohms is very much the 'lab standard for RF/video kit that never gets
to see an aerial'..


a great many professional aerials (or should I say antennae?) are of 50ohm
impedance.

Unlikely. Not at the raw antenna level. You HAVE to match using some
kind of extra circuitry for any other impedance than 75 ohm (quarter
wave) or 300 ohm (half wave).



All pro two-way radio broadcast TV and VHF FM & DAB are 50 ohms as are
the cable connectors, transmitter outputs etc.* Most all using dipoles as
the radiating elements have a "BALUN" BALance to UN Balance transformer.*

Which matches as well. Once you have anything other than a pure aerial
in the mix, you can run at any arbitrary impedance.

But in the contexxt of finding a use for 50 ohm cable domestically, good
luck with that.,




Some use Gamma or Delta matches but the idea is the same to match the
balanced dipole to the un balanced co-axial cables except those
occasions where LF MF and HF arrays are used.

Quite a complex subject overall!....


very.


--
Future generations will wonder in bemused amazement that the early
twenty-first centurys developed world went into hysterical panic over a
globally average temperature increase of a few tenths of a degree, and,
on the basis of gross exaggerations of highly uncertain computer
projections combined into implausible chains of inference, proceeded to
contemplate a rollback of the industrial age.

Richard Lindzen

On Sun, 22 May 2016 20:22:54 +0100, Tim Streater
wrote:

In article , T i m
wrote:

On Sun, 22 May 2016 15:47:22 +0100, Tim Streater
wrote:

Well on 10base5, vampire taps were all there were.

Nope. If you were doing it fully you fitted TNC connectors to the ends
of the RG8 and used Transceivers with TNC connectors. ;-)

You mean something like the Cabletron ST-500-02?

Yup.

OK, I see what you
mean. I don't know whether we ever considered those, but either you
have to design your segment and know where all the taps will be needed
ahead of time,

Possible but in most cases I doubt it.

or you need to take the segment OOS to add one (hmm, I
suppose that's true of all thinnet too).

Quite. Most of that I did and outside hours, simply because it was
easier (that trying to get everyone off the net) and quicker. Or I
would go in over the weekend if it was a longer job and take the time
off in lieu.

Like things (inanimate and otherwise) that can sense you are in a rush
or that things are important and play up accordingly, you could
guarantee that if I had some new hardware to install or something that
required a bit of piece and quiet to read up on or configure properly
the phone wouldn't stop ringing (I ran the 'Telephone Help Desk' for
customers) or there would be a constant flow of users though my door
with (mostly finger) trouble. Hence why I'd often leave it to outside
working ours.

I suspect we gave up on vampire taps altogether and just had 10base5
backbones with a few repeaters on them and thinnet for everything else.

ThickNet was handy if you had a long thin building but ours was
several 'wings' over a couple of floors so a Star topology was better
suited.

10baseT hadn't really got going by the time I moved back to the UK.

It didn't even exist when I first offered to put 'a network' into our
building g. My logic for proposing it to them was that 'We are a
datacoms Co after all' and 'it would save a lot of time' (and so
money) versus 'Sneakernet'. ;-)

But I still have my Cabletron mug!

I've had to take such things out of daily use because it always seems
the 'good' mugs get broken whilst the 'couldn't care less' mugs will
survive being dropped on concrete. ;-(

Cheers, T i m

On Sun, 22 May 2016 14:12:52 +0100, John Rumm
wrote:

snip

Indeed - quite handy for situations in even small offices where you have
two unconnected businesses sharing resources or internet connections,
but you want some isolation between them.

You can get 'isolation' between machines on some routers but a managed
switch might be good for my mate in the PC shop to isolate customer
machines in for repair from his own / shop machines?

Or I wonder if you could use the OpenWRT router software (two LAN
ports) I installed on his TP-Link cable router to in turn feed two
switches (one for the shop and another for the 'guest' machines)?

He would have to have the WSUS server on the guest network as they are
the ones that need updating.

Cheers, T i m

On Sat, 21 May 2016 20:37:15 +0100, John Rumm
wrote:

snip

[1] In the end I had to unpatch everything on the switch, just leaving
the router and my laptop. Left that pinging the router, and then watched
carefully as I re-patched each wall port - eventually found one that
caused it to apparently die.

snip

I had to do similar for a mate the other day. OpenReach modem to BT
Hub to an 8 port switch. They had been speaking to BT and BT had asked
them to pull the power leads from the PC's. Luckily they had only
pulled the power leads from the monitors rolls eyes.

The 8 port switch was showing some strange signs and a power cycle
didn't seem to resolve it. So I pulled all the Ethernet cables and
just connected the link to the router and one PC. All was well so I
just re-connected the known leads (to local PC's and printers) one at
a time and all stayed well. Plugging one of the last two cables in
seemed to upset the switch so I left them unconnected (as no one knew
where they went in any case). I'm sure they will hear if someone (or
thing) doesn't have any Internet connection. ;-)

Cheers, T i m

On 28/05/2016 22:32, T i m wrote:
On Sun, 22 May 2016 14:12:52 +0100, John Rumm
wrote:

snip

Indeed - quite handy for situations in even small offices where you have
two unconnected businesses sharing resources or internet connections,
but you want some isolation between them.

You can get 'isolation' between machines on some routers but a managed
switch might be good for my mate in the PC shop to isolate customer
machines in for repair from his own / shop machines?

Yup, very much so...

Or I wonder if you could use the OpenWRT router software (two LAN
ports) I installed on his TP-Link cable router to in turn feed two
switches (one for the shop and another for the 'guest' machines)?

There are lots of ways of doing it. He possibly need a customer wifi
network as well - where devices can access the internet, but not see
each other or the rest of the LAN

He would have to have the WSUS server on the guest network as they are
the ones that need updating.

Cheers, T i m



--
Cheers,

John.

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