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Old April 9th 04, 07:29 PM
Peter Tate
 
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Default shunt fed AM Sticks

Hi NG People,

Does anyone know where there is a good site on the web for info on Shunt fed
towers and the like?

Regards,

peter




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Old April 10th 04, 01:37 AM
Philip de Cadenet
 
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Hello Peter,

Does anyone know where there is a good site on the web for info on Shunt fed
towers and the like?


I'm sure you'll find something in the archives at the BE site:

http://www.broadcast.net/

Use the drop-down menu.

Also consider joining one of their mailing lists. Full of experienced
engineers who I'm sure can point you to other published work.

Who is Station X AM?
--
Philip de Cadenet G4ZOW
Transmitters 'R' Us
http://www.transmittersrus.com

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Old April 10th 04, 01:37 AM
Peter H.
 
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Does anyone know where there is a good site on the web for info on Shunt fed
towers and the like?


I doubt if you could get a new shunt excited tower licensed today.

However, in the mid-1960s Broadcast Engineering had an article (or was it
articles) on shunt excited towers.



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Old April 10th 04, 11:01 PM
Clock
 
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Curious to know what the objections to shunt feed would be...



"Peter H." wrote in message
...


Does anyone know where there is a good site on the web for info on Shunt

fed
towers and the like?


I doubt if you could get a new shunt excited tower licensed today.

However, in the mid-1960s Broadcast Engineering had an article (or was it
articles) on shunt excited towers.








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Old April 10th 04, 11:01 PM
Peter Tate
 
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Thanks heaps guys,

I'm in the land down under. We have here a licensing category where they
issue the top end of the broadcast band between1611 to 1701 for what is
called Narrowband Area Services. This in Australia is outside the "official"
broadcasting bands. Also we are on 9khz steps here. All this is inline with
the ITU rules. So it leaves the gap where you finsh at 1710.

I'm not sure of the exact politics but here we follow the same specs as
Europe under the conventions of the ITU. We also have TWO regulators here
one for RADIO Emmisions (two ways / CB etc etc etc). The other one
"regulates" everything termed "broadcasting". This is the Australian
Broadcasting Authority the other is Australian Communications Authority.

As one can see one needs to operate within the other for issueing of TV
AM/FM radio licenses. When you ask for a freq NOT within the Broadcasting
Bands the fun starts! SW here is not concidered viable but the ACA sees alot
of HF Spectrum going to waste so issues TXer licenses. The same thing
happened with the little golden bit on top of our Broadcast Band 1611 to
1701. The ACA will issue licenses to TRANSMIT on them under specs less than
broadcast and more like a two way quality (no one does though).

By definition you are operating a "broadcasting service" as seen by the
ABA,but you don't need to worry about the ABA's silly rules as you are not
under their area of control. If they really want to get you they could, on
content regardless but you are not running an illegal TX this is covered by
the ACA.

Station X runs as a netcaster currently from Australia. I've got a few of
these NAS licenses at 400 watts and one SW on 2368khz designed mainly for
domestic HF coverage.

There is not much available in Australia on tricky aerial designs. The
station is not any really big operation so the investment needs to be
comparible. Setting up a 40 meter mast (although needed ) is not going to
happen. We have an interesting rule here for town planing that says Amateur
Radio operators can erect a tower up to 100 feet without council
permisssion. If it was for commercial purposes no dice needs approval----oh
dear?????

A power pole and conduit carring the MF wires up with a beam on top some guy
wires coming down at 45 degrees sounds like an amatuers setup.

so thanks heaps guys.

www.stationx.com.au to read up on the "X"



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Old April 12th 04, 02:04 AM
Peter H.
 
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What is the problem that would prevent licensing today?


The polar plot is not circular (which it is, for series excited towers).

Nevertheless, there is at least one DA which uses shunt excited towers.

Incredibly enough, the day and night patters are mirror images of each other
(null towards the west during days, null towards the east during nights).


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Old April 12th 04, 02:04 AM
Patrick Griffith, N0NNK / WPE9HVW
 
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The problem isn't with shunt feed in particular. The increasingly
popular folded vertical on a grounded base tower is actually a form of
shunt feed.

A lot of people associate the term shunt feed with slant wire feed.
Slant wire feed is where the problem lies. While there are many of these
systems still operating due to grandfathering (KFBC in Cheyenne WY for
example) the FCC will generally not allow any new installations with
this feed arrangement because the slant wire itself introduces an
unwanted directional component into the radiation pattern. However, I
have heard that the FCC has allowed a few slant wire feeds for daytime
only stations under an STA.

Patrick Griffith, N=D8NNK, Westminster, CO

http://community.webtv.net/N0NNK/
http://community.webtv.net/AM-DXer/


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Old April 12th 04, 02:04 AM
Philip de Cadenet
 
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Peter,

Station X runs as a netcaster currently from Australia. I've got a few of
these NAS licenses at 400 watts and one SW on 2368khz designed mainly for
domestic HF coverage.


This would be part of the old HF marine band here in the UK.

Out of interest do Australian broadcasters use AM on this band and if so
which make of transmitter?
--
Philip de Cadenet
Transmitters 'R' Us
http://www.transmittersrus.com

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Old April 13th 04, 03:23 AM
Peter Tate
 
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Phil,

AM broadcasting here is on the 521 to 1602 khz for normal broadcasting
stations. The 2368Khz is concidered a SW freq here although the lowest of
them. Yes here it is "shared" with "broadcast" and "mobile or fixed"
services. I'm not sure on the exact freq limits but this is the first of the
Shortwave Bands as designated by the ITU. It isn't concidered anything too
usefull for the purposes of International Broadcasting. That happens from
about 5 mhz upwards plus needs to be shared on a time table basis as you
would know.

So here we find a lot of long distance two way system for long distance
trucking companys and a system here called the Royal Flying Doctor Service.
Also a mob that are a FWD club have a network of stations around the
country. Alot of this is all done now on Sat phones etc, so the ACA are
looking at what to do with stacks of HF spectrum being left dorment.

Here TXers are AWA / Blyth / RVR / Rhode & Shcwarz / Harris -------thats
about as far as memory goes for now!





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