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'[OT]:: and you think that YOU have got wiring prob'
2011\03\03@131918 by RussellMc

face picon face
Interesting street wiring practices, Xian, China.
High res version available by clicking 3rd button from right above picture.

             http://bit.ly/WiringProblems<http://public.fotki.com/RussellMc/atw/china1102/rmatw1102/and-you-think-that.html>

More photos are loading into this album at present. There should be 45 or so
in a few hours time.
None of the others are overly EE related.


    Russel

2011\03\03@133216 by Olin Lathrop

face picon face
RussellMc wrote:
http://bit.ly/WiringProblems<http://public.fotki.com/RussellMc/atw/china1102/rmatw1102/and-you-think-that.html>

"Page not found"


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\03\03@133708 by Joe Koberg

flavicon
face
On 2011-03-03 12:32, Olin Lathrop wrote:
> RussellMc wrote:
> http://bit.ly/WiringProblems<http://public.fotki.com/RussellMc/atw/china1102/rmatw1102/and-you-think-that.html>
>
> "Page not found"


There are two links juxtaposed there, and Thunderbird (at least) had no problem distinguishing/opening one or the other in the browser when clicked, despite the lack of spacing.

http://bit.ly/WiringProblems

http://public.fotki.com/RussellMc/atw/china1102/rmatw1102/and-you-think-that.html


Joe Koberg


Joe

2011\03\03@141409 by RussellMc

face picon face
> On 2011-03-03 12:32, Olin Lathrop wrote:
> > RussellMc wrote:
> > http://bit.ly/WiringProblems<public.fotki.com/RussellMc/atw/china1102/rmatw1102/and-you-think-that.html>
> >
> > "Page not found"

> There are two links juxtaposed there, and Thunderbird (at least) had no
> problem distinguishing/opening one or the other in the browser when
> clicked, despite the lack of spacing.
>
> http://bit.ly/WiringProblems
>
> http://public.fotki.com/RussellMc/atw/china1102/rmatw1102/and-you-think-that.html

Yes.
My bad.
Intended to substitute the bit.ly link for the actual address but
managed not t delete the original.
bit.ly is interesting as it provides a breakdown by country (or
region) and also a traffic with time graph.
Country names seem to have vanished off the graph lately - proably the
Russian translation ghost at play.


2011\03\03@141831 by RussellMc

face picon face
Strange.
I just looked at my original post and on my copy I HAVE deleted the
original link.
Mr 'Don't be consistent' has managed to regurgitate it as it crossed the globe.
How interesting.

>> > http://bit.ly/WiringProblems

Questions:

Why do they coil the cables - are they wanting to reuse them as whole
lengths once their present task is done?

What sort of cable is it? Has a coax like appearance. Broadband distribution?


2011\03\03@142539 by Manu Abraham

picon face
On Fri, Mar 4, 2011 at 12:47 AM, RussellMc <spam_OUTapptechnzTakeThisOuTspamgmail.com> wrote:
> Strange.
> I just looked at my original post and on my copy I HAVE deleted the
> original link.
> Mr 'Don't be consistent' has managed to regurgitate it as it crossed the globe.
> How interesting.
>
>>> > http://bit.ly/WiringProblems
>
> Questions:
>
> Why do they coil the cables - are they wanting to reuse them as whole
> lengths once their present task is done?
>
> What sort of cable is it? Has a coax like appearance. Broadband distribution?

Looks like coax, could be broadband. By around 2006 they switched to
digital cable, so it could possible be DVB-C as well.

Man

2011\03\03@143322 by Olin Lathrop

face picon face
RussellMc wrote:
> Why do they coil the cables

Leaving them dangling would make a mess and invite vandalism.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\03\03@152753 by V G

picon face
On Thu, Mar 3, 2011 at 2:33 PM, Olin Lathrop <.....olin_piclistKILLspamspam@spam@embedinc.com>wrote:

> RussellMc wrote:
> > Why do they coil the cables
>
> Leaving them dangling would make a mess and invite vandalism.


All that current flowing through those "coils" must create a nice strong EM
field

2011\03\03@153347 by Olin Lathrop

face picon face
V G wrote:
> All that current flowing through those "coils" must create a nice
> strong EM field?

Not if it's coax or otherwise has equal currents flowing in opposite
directions in close proximity to each other.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\03\03@161133 by Manu Abraham

picon face
On Fri, Mar 4, 2011 at 1:03 AM, Olin Lathrop <olin_piclistspamKILLspamembedinc.com> wrote:
> RussellMc wrote:
>> Why do they coil the cables
>
> Leaving them dangling would make a mess and invite vandalism.


Other than that, there would be Line Amplifiers/Drivers driving those
cables Those cables do look cheap/thin (probably), unlike the rather
thick low capacitance/loss cables. In some cases, coiling cables can
act as an attenuator in cases of overdrive at the consumer equipment
side Simple thing, but works well

2011\03\03@161705 by Michael Watterson

face picon face
On 03/03/2011 19:25, Manu Abraham wrote:
>> >  What sort of cable is it? Has a coax like appearance. Broadband distribution?
> Looks like coax, could be broadband. By around 2006 they switched to
> digital cable, so it could possible be DVB-C as well.
no such thing.

Fibre is Fibre.
Twisted pair is twisted pair
Coax is coax

all can carry baseband or carriers
Signal can be pure analogue or analogue-ish signals coded with Digital information
(even on the Fibre)

Multi-pair Cat3 phone cable, trunk Coax and multi-fibre optic cable can all look the same on outside if designed to be strung on poles.

DOCSIS (Cable Broadband) uses CDMA or TDMA for uplink (usually TDMA) and DVB-C for Downlink.
Coax can carry 5..65MHz DOCSIS uplink, 88.. 108 FM Radio, 110MHz to 1200MHz in 8MHz channels, any of which can be Analogue TV, DVB-C regular TV mux  (multiple Digital channels), DVB-C TV mux carrying "Switched Video" or DVB-C carrying DOCSIS downlink.

If you are clever in an Apartment block you can put on ONE coax per outlet
5..65MHz DOCSIS uplink, 88.. 108 FM Radio, 110MHz to 500MHz in 8MHz channels (,any of which can be Analogue TV, DVB-C regular TV mux  (multiple Digital channels), DVB-C TV mux carrying "Switched Video" or DVB-C carrying DOCSIS downlink.)with gap for Off Air reception of DAB at 220MHz, 500MHz to 790MHz off Air DVB-T, 790MHz to 900MHz DVB-C and 950MHz to 2100MHz from Satellite Dish(es) with 4x Quattro and Multiswitch(es).

With suitable gear you can feed 2000 rooms from Cable Company Trunk, DAB and UHF aerial and Dish
http://www.techtir.ie/tv-radio/satellite-distribution

Setup in photo used to feed 64 outlets in 32 pairs for Satellite PVR (needs 2x coax). So one 1/2 the system had Cable Company feed and other 1/2 had off air TV/Radio aerials. The two coax feed to PVR went to a 4 x f-Connector wall plate with 2x Sat/TV 900MHz Diplexers, and sockets labelled Cable, Sat, Sat  TV/Radio
28E, 23E, 19E and 13E on the satellite part of system.
two sets of helical filters to combine DX aerials on mast for Off Air UK TV with Local Irish TV.
So FM Radio, Broadband, DAB, Analogue and Digital Irish and UK Terrestrial TV and 4 x Satellites.(if receiver has Diseqc) 28E on Port one as Sky boxes don't do Disecq.

EMP-Centauri 16 (4 x quattro) + passive TV in / 16 out multiswitches  driven by amps and 5MHz to 2100MHz bidirectional trunk splitters. The 5MHz to 65MHz Cable Broadband worked fine back up through it all. Proper 110channel rated Broadband/TV bidirectional Cable Trunk amps and splitters used to drive 1/2 of the 17th terrestrial connection on Multiswitches

2011\03\03@164302 by Manu Abraham

picon face
On Fri, Mar 4, 2011 at 2:46 AM, Michael Watterson <.....mikeKILLspamspam.....radioway.org> wrote:
> On 03/03/2011 19:25, Manu Abraham wrote:
>>> >  What sort of cable is it? Has a coax like appearance. Broadband distribution?
>> Looks like coax, could be broadband. By around 2006 they switched to
>> digital cable, so it could possible be DVB-C as well.
> no such thing.


I guess it is not fiber, due to the distribution amplifiers in the
picture. Fiber cannot carry Phantom power .. (just a guess)


{Quote hidden}

Yeah, I have DOCSIS (Cable Broadband) and DVB-C at my appartment,
that's what I am using presently.


{Quote hidden}

DAB is dead AFAIK.

If you are clever enough, you can all of that on a single Ethernet
cable as well ;-)
http://linuxtv.org/hg/dvb-apps/file/1f246cbf8104/util/gnutv

2011\03\03@170622 by Michael Watterson

face picon face
On 03/03/2011 21:43, Manu Abraham wrote:
> DAB is dead AFAIK.
I agree.

But someone should tell BBC, RTE, UK gov and Irish Gov

2011\03\03@171938 by Michael Watterson

face picon face
On 03/03/2011 20:25, V G wrote:
> All that current flowing through those "coils" must create a nice strong EM
> field?
actually if was coax, there is no field at all from "proper" currents, but it would act as a common mode choke for common mode signals.

In BBC they had a thing that looked like a 10kW mains transformer. It was wound with RG59 75 ohm coax or similar and acted as a mains hum common mode filter to stop "earth loops". The only effect on the video was the simple length of cable used.

2011\03\03@172053 by Michael Watterson

face picon face
On 03/03/2011 21:11, Manu Abraham wrote:
> Other than that, there would be Line Amplifiers/Drivers driving those
> cables Those cables do look cheap/thin (probably), unlike the rather
> thick low capacitance/loss cables. In some cases, coiling cables can
> act as an attenuator in cases of overdrive at the consumer equipment
> side Simple thing, but works well.
coiling doesn't affect the actual signal at all. Only common mode

2011\03\03@175354 by Manu Abraham

picon face
On Fri, Mar 4, 2011 at 3:50 AM, Michael Watterson <EraseMEmikespam_OUTspamTakeThisOuTradioway.org> wrote:
> On 03/03/2011 21:11, Manu Abraham wrote:
>> Other than that, there would be Line Amplifiers/Drivers driving those
>> cables Those cables do look cheap/thin (probably), unlike the rather
>> thick low capacitance/loss cables. In some cases, coiling cables can
>> act as an attenuator in cases of overdrive at the consumer equipment
>> side Simple thing, but works well.
> coiling doesn't affect the actual signal at all. Only common mode.

It sure does. http://www.ham-radio.com/k6sti/balun.ht

2011\03\03@180907 by Olin Lathrop

face picon face
Manu Abraham wrote:
>> coiling doesn't affect the actual signal at all. Only common mode.
>
> It sure does. http://www.ham-radio.com/k6sti/balun.htm

That's a balun, otherwise known as common mode choke.  The are explicitly
exploiting the fact that coiling adds inductance to the common mode path but
not to the differential path.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\03\03@182353 by Manu Abraham

picon face
On Fri, Mar 4, 2011 at 4:39 AM, Olin Lathrop <olin_piclistspamspam_OUTembedinc.com> wrote:
> Manu Abraham wrote:
>>> coiling doesn't affect the actual signal at all. Only common mode.
>>
>> It sure does. http://www.ham-radio.com/k6sti/balun.htm
>
> That's a balun, otherwise known as common mode choke.  The are explicitly
> exploiting the fact that coiling adds inductance to the common mode path but
> not to the differential path.

After writing that only, I thought that attenuation would be in the common mode.

2011\03\03@185605 by Brian Gregory

flavicon
face
In-Reply-To: <@spam@AANLkTim9wk3RJjbqN37FevT-c-OoX2M3hrF3m4rE2au5KILLspamspammail.gmail.com>

Manu,

{Quote hidden}

Those coils only become baluns because unwanted common mode currents are illiminated. Nothing else is happening.

Brian Gregory.
RemoveMEbriangTakeThisOuTspamcix.compulink.co.uk

2011\03\04@020507 by Manu Abraham

picon face
On Fri, Mar 4, 2011 at 5:25 AM, Brian Gregory
<spamBeGonebriangspamBeGonespamcix.compulink.co.uk> wrote:
> In-Reply-To: <TakeThisOuTAANLkTim9wk3RJjbqN37FevT-c-OoX2M3hrF3m4rE2au5EraseMEspamspam_OUTmail.gmail.com>
>
> Manu,
>
>> On Fri, Mar 4, 2011 at 3:50 AM, Michael Watterson <RemoveMEmikespamTakeThisOuTradioway.org> wrote:
>> > On 03/03/2011 21:11, Manu Abraham wrote:
>> >> Other than that, there would be Line Amplifiers/Drivers driving those
>> >> cables Those cables do look cheap/thin (probably), unlike the rather
>> >> thick low capacitance/loss cables. In some cases, coiling cables can
>> >> act as an attenuator in cases of overdrive at the consumer equipment
>> >> side Simple thing, but works well.
>> > coiling doesn't affect the actual signal at all. Only common mode.
>>
>> It sure does. http://www.ham-radio.com/k6sti/balun.htm
>>
>
> Those coils only become baluns because unwanted common mode currents are
> illiminated. Nothing else is happening.

Ah, yes. true. They are not simply there to avoid dangling and vandalism.

Generally, a few turns of copper on the PCB of a RF receiver for an TL
impedance match is used, which came to mind suddenly, when I read
dangling and vandalism (equivalent circuit: R-L series, C across the
said R-L, parasitic capacitance Cp of PCB from that output to GND).

Other than that, in many cases high speed digital communication
devices also see the track as a TL.

As I wrote earlier, after writing that post only did I think that
attenuation would be in the common mode as both conductors are
involved, thereby achieving a higher CMRR

2011\03\04@023531 by Yigit Turgut

picon face
On Thu, Mar 3, 2011 at 10:34 PM, Olin Lathrop <olin_piclistEraseMEspam.....embedinc.com> wrote:
> V G wrote:
>> All that current flowing through those "coils" must create a nice
>> strong EM field?
>
> Not if it's coax or otherwise has equal currents flowing in opposite
> directions in close proximity to each other.

Don't misdirect people here Olin, you obviously don't have any
theoretical background in field and wave theory

2011\03\04@025124 by RussellMc

face picon face
> >> All that current flowing through those "coils" must create a nice
> >> strong EM field?

> > Not if it's coax or otherwise has equal currents flowing in opposite
> > directions in close proximity to each other.

> Don't misdirect people here Olin, you obviously don't have any
> theoretical background in field and wave theory.

If you are going to correct incorrect impressions then it would be
very useful if your could provide alternative information or a website
link.


           Russel

2011\03\04@044044 by alan.b.pearce

face picon face
> DAB is dead AFAIK.
>
Not in the UK - they are still trying to pass it off as the best thing in radio since sliced bread. There are threats to close down the AM & FM bands and have all the radio on DAB.
-- Scanned by iCritical.

2011\03\04@052051 by Manu Abraham

picon face
On Fri, Mar 4, 2011 at 3:09 PM,  <EraseMEalan.b.pearcespamstfc.ac.uk> wrote:
>> DAB is dead AFAIK.
>>
>
> Not in the UK - they are still trying to pass it off as the best thing in radio since sliced bread. There are threats to close down the AM & FM bands and have all the radio on DAB.


I was of the belief that most of Europe switched over to DVB-T/H ?
http://www.ebu.ch/fr/technical/trev/trev_305-skiold.pdf

The reason why DAB was considered near to extinction was DAB+ emerged
then DMB, later on DVB-H, DVB-H being compatible with DVB-T except for
the encapsulation MPE-FEC and the additional interleaver modes, was
thought to be superset of DAB/DAB+/DMB.

Interesting, to know that DAB is still active. A bit more surprised
that with DVB-T2 adoption, DAB is still active

2011\03\04@060622 by IVP

face picon face

>> DAB is dead AFAIK.
>>
>
> Not in the UK - they are still trying to pass it off as the best thing
> in radio since sliced bread. There are threats to close down the
> AM & FM bands and have all the radio on DAB

"Cambridge, for a while, was the home of Nigel Seagrove, the
electronics engineer who did much work on DAB radio. He was
married in the beautiful Saxon church of St Mary's, before the
wedding party moved on to The Park Hotel. Guests reported
that, while they enjoyed the wedding ceremony, the reception
was rubbish"

ISIHAC  26/07/1

2011\03\04@084748 by Olin Lathrop

face picon face
Manu Abraham wrote:
>> That's a balun, otherwise known as common mode choke. The are
>> explicitly exploiting the fact that coiling adds inductance to the
>> common mode path but not to the differential path.
>
> After writing that only, I thought that attenuation would be in the
> common mode.

It is.  That's exactly the point of a balun.  It adds impedence to the
unwanted common mode signal while adding as little as possible to the real
differential mode signal.

Baluns are often used in RF applications as single ended to differential
converters.  For example, the final transmitter output could be single ended
with respect to ground.  That works fine for the transmitter and for a
single ended antenna such as one that relies on a ground plane.  However, if
you have a symmetric antenna you want both sides with equal and opposite
signals with respect to ground.  A balun between the transmitter and such a
antenna achieves that for various levels of good enough.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\03\04@090805 by Olin Lathrop

face picon face
Yigit Turgut wrote:
>>> All that current flowing through those "coils" must create a nice
>>> strong EM field?
>>
>> Not if it's coax or otherwise has equal currents flowing in opposite
>> directions in close proximity to each other.
>
> Don't misdirect people here Olin, you obviously don't have any
> theoretical background in field and wave theory.

???

I think you may need to look up what "coax" means.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\03\04@093853 by Michael Watterson

face picon face
On 04/03/2011 13:48, Olin Lathrop wrote:
> It is.  That's exactly the point of a balun.  It adds impedence to the
> unwanted common mode signal while adding as little as possible to the real
> differential mode signal.
>
> Baluns are often used in RF applications as single ended to differential
> converters.  For example, the final transmitter output could be single ended
> with respect to ground.  That works fine for the transmitter and for a
> single ended antenna such as one that relies on a ground plane.  However, if
> you have a symmetric antenna you want both sides with equal and opposite
> signals with respect to ground.  A balun between the transmitter and such a
> antenna achieves that for various levels of good enough.
>
I vote that Olin knows what he is talking about on this.

2011\03\04@095449 by RussellMc

face picon face
> I vote that Olin knows what he is talking about on this.

Apart, perhaps,  from  the need for a spilling chucker and or brain
resetting :-), as per recent comments on what we can and can't see in
what we write.

>> It is.  That's exactly the point of a balun.  It adds impedence to the
>> unwanted common mode signal while adding as little as possible to the real
>> differential mode signal.


           R

2011\03\04@095919 by jim

flavicon
face


All,

BALUN is a contraction for BALanced-UNbalanced.  An unbalanced line is
one in which one side has a  different impedance with respect to ground. COAX is an UNbalanced line.
 
Alternately, twin lead is BALanced. ie both sides have equal impedance
WRT ground.

A typical RF transmitter has an unbalanced output generally.  And if
you are going to drive a ground plane
antenna, this is fine.  COAX is a good fit for this job.  However, if
you were to drive a DIPOLE antenna
for instance, this type of antenna is BALanced.  Using COAX directly
will work, but it won't be optimum.
And you'll also run the risk of radiating RF from the line at various
places where you don't want it to  radiate from.  So, in this case, you could use some COAX connected in a
way to perform the BALUN function.
This is a transformer of sorts.  And it transforms a single unbalanced
signal to a differential balanced  signal.

This is a rather simplified explanation, but should suffice to get the
idea across to most members of the
list.  I'm sure there are several HAM radio operators on this list (I
am KA9QHR) that can verify (or
refute) my explanation.

Regards,

Jim

> ---{Original Message removed}

2011\03\04@100818 by Mark Rages

face picon face
On Thu, Mar 3, 2011 at 12:18 PM, RussellMc <RemoveMEapptechnzEraseMEspamEraseMEgmail.com> wrote:
> Interesting street wiring practices, Xian, China.
> High res version available by clicking 3rd button from right above picture.
>
>              http://bit.ly/WiringProblems<http://public.fotki.com/RussellMc/atw/china1102/rmatw1102/and-you-think-that.html>
>
> More photos are loading into this album at present. There should be 45 or so
> in a few hours time.
> None of the others are overly EE related.
>
>
>     Russell

Are those white nylon (UV unstable) wire ties?  The wiring problems
will come after a few years of sun.

Regards,
Mark
markrages@gmail
-- Mark Rages, Engineer
Midwest Telecine LLC
RemoveMEmarkragesspam_OUTspamKILLspammidwesttelecine.com

2011\03\04@101252 by Olin Lathrop

face picon face
RussellMc wrote:
> Apart, perhaps,  from  the need for a spilling chucker and or brain
> resetting :-), as per recent comments on what we can and can't see in
> what we write.
>
>>> It is. That's exactly the point of a balun. It adds impedence to the
>>> unwanted common mode signal while adding as little as possible to
>>> the real differential mode signal.

OK, I'll bite.  What exactly is wrong with this statement?


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\03\04@102102 by Olin Lathrop

face picon face
jim@jpes.com wrote:
>  BALUN is a contraction for BALanced-UNbalanced.  An unbalanced line
> is
> one in which one side has a
>  different impedance with respect to ground.

Now that we've beat to death what a balun is, I agree with Russell that
these coils are unlikely to be deliberate baluns.

My guess is the reason for the extra wire is not electrical.  They may be
service loops to make future changes easier.  It's hard to tell from a
single picture at a single point in time, but this could be a temporary
installation.  Maybe the phone pole is scheduled to be moved soon.
Sometimes things are done for short term expedience or don't make sense
without context within the bigger picture.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2011\03\04@103007 by RussellMc

face picon face
>>>> It is. That's exactly the point of a balun. It adds impedence to the
>>>> unwanted common mode signal while adding as little as possible to
>>>> the real differential mode signal.

> OK, I'll bite.  What exactly is wrong with this statement?

Spilling era.
Easily done.
But, brain tends to not see such after a while.
Mine anyway :-).

           http://en.wikipedia.org/wiki/Electrical_impedance

    R

2011\03\04@103021 by Roger, in Bangkok

face
flavicon
face
Retrying ... I swear I changed it to [OT] before :/

RiB

On Fri, Mar 4, 2011 at 21:59, Roger, in Bangkok <RemoveMEmerciesTakeThisOuTspamspamcscoms.com> wrote:

{Quote hidden}

>> -

2011\03\04@113559 by Michael Watterson

face picon face
On 04/03/2011 15:21, Olin Lathrop wrote:
> Now that we've beat to death what a balun is, I agree with Russell that
> these coils are unlikely to be deliberate baluns.
>
> My guess is the reason for the extra wire is not electrical.  They may be
> service loops to make future changes easier.  It's hard to tell from a
> single picture at a single point in time, but this could be a temporary
> installation.  Maybe the phone pole is scheduled to be moved soon.
> Sometimes things are done for short term expedience or don't make sense
> without context within the bigger picture.

It's the occam explanation I think.

I'd agree.

But a coil of coax never hurts. one at TV aerial (as tight as won't damage coax dielectric or screen, about 3 or 4 turns) and at TV socket, can reduce interference from CB radio, or even reduce peak voltage static discharge if  storm (nothing helps a direct strike, that removes the Chimney usually!).

If it's a cheap "contract" yagi with no built in balun, then it acts actually as a balun.

A 1:1 RF trans former wired with the two windings in series breaking the two wires, rather than wired as DC isolation has advantage that it's wider band for desired differential signal, passes DC power supply and audio signalling. The DC won't saturate it as the DC currents cancel if a single bifilar wind is done to get the two 1:1 windings. it's not uncommon to see RG174 miniature coax or twisted pair of particular impedance wound on a ferrite.

If a separate "balun" is wound like this to feed DC to a pair of FETs (the fields  DC bias cancels, but separate RF chokes would saturate), they can be driven push-pull. They can have about 25 Ohm output, so a 2nd "balun" like this connects to 50 output via two capacitors for DC isolation.

A third balun used to drive gates. You can achieve 100MHz to 2000MHz  with suitable ferrite, which is impossible using the baluns like conventional 1:1 isolation transformers.

2011\03\04@115526 by RussellMc

face picon face
>  or even reduce peak voltage
> static discharge if  storm (nothing helps a direct strike, that removes
> the Chimney usually!).

If cable is run into the ground - twisted pair or coax etc, then
providing a loop or few at ground level will often result in a
Lightning strike causing burn-through to ground at a point on the
loop(s).

This does not make sense analytically as the loop inductance is too
small to explain this effect. But, it is reported to work. Stopping
lightning before it gets into 'real stuff' is a good idea [tm].


    Russell

2011\03\04@121944 by Carl Denk

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It is common here, where when the fine particled (clay/silt) soils freeze and expand sometimes lifting the surface an inch or 2, to provide a loop below ground in cables and tubing to allow for the movement. Concrete drives and walks next to buildings with deep (below frost line) foundations need a bond breaker to allow movement of the concrete vertically. If not done, the concrete drive/walk has been known to lift the building if there is not sufficient weight.

On 3/4/2011 11:54 AM, RussellMc wrote:
>>   or even reduce peak voltage
>> static discharge if  storm (nothing helps a direct strike, that removes
>> the Chimney usually!).
>>      
> If cable is run into the ground - twisted pair or coax etc, then
> providing a loop or few at ground level will often result in a
> Lightning strike causing burn-through to ground at a point on the
> loop(s).
>
> This does not make sense analytically as the loop inductance is too
> small to explain this effect. But, it is reported to work. Stopping
> lightning before it gets into 'real stuff' is a good idea [tm].
>
>
>       Russell
>
>

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