[cma-l] community AM
Ian Hickling
transplanfm at hotmail.com
Thu Sep 17 20:09:12 BST 2015
Reverting to pedantic engineer terms - the two 100W AM CRs are not "on" ILR masts - but will have taken over former ILR frequencies, powers and sites and will be using the existing antennas which are vertical radiators in the form of stayed masts.
The others will have had to provide their own sites and antennas - we installed the 1W unit in Camberley.
Ian Hickling
Partner
Office: 01635 578435 (7am-11pm UK time)Carphone: 07530 980115 (only responds when driving)6 Horn Street, Compton, NEWBURY, RG20 6QS
Date: Thu, 17 Sep 2015 11:08:21 +0100
From: ravensound at pilgrimsound.co.uk
To: cma-l at mailman.commedia.org.uk
Subject: Re: [cma-l] community AM
Hello Ian et al,
Looks like this thread has split, however, just a couple of
points, of the six (other thread!) AMCRs two are in London on ILR
masts and the other four have mast heights listed as between 10
and 14 metres and emrps from 1-70 watts. Clearly the non-ILR masts
are nowhere near quarter wave radiators. I mentioned the likely
range of 70 watt emrp as being around 8km which I think may be due
to greater flexibility in licensing due to the different situation
on AM. Nevertheless it is a matter for individual licensees how
they build their business case. Increasing coverage with
disproportionate cost escalation may not be advisable in every
case.
Regards, Tony
On 16/09/15 20:46, Ian Hickling wrote:
Can I once again point out that "the 5km radius for
community stations" - coupled with the 25W horizontal plus 25W
vertical "standard allowance" for FM is a nominal guide for
Applicants and not a norm or a limit.
37 of the current 233 stations on air use more than that
because they have conclusively shown Ofcom the level of power
they need to cover their Community.
AM is influenced most I respectfully suggest by aerial design.
The answer to your last question Phil is "In practical
terms - no".
Ian Hickling
Partner
Office: 01635 578435 (7am-11pm UK time)
Carphone: 07530 980115 (only responds when driving)
6 Horn Street, Compton, NEWBURY, RG20 6QS
> To: cma-l at mailman.commedia.org.uk
> From: office at fantasyradio.co.uk
> Date: Wed, 16 Sep 2015 11:36:40 +0100
> Subject: [cma-l] community AM
>
> Indeed, Tony.
>
> Your figures fit in with my own experience over the
years. Once again,
> the 5km radius for community stations works out.
>
> It's worth remembering that with AM, it's less affected
by topography
> and even tx location. Does anyone know if Ofcom produce
any helpful
> guidance or data in regard to AM? (er, sorry, medium
wave)
>
>
> Phil
>
> On 16/09/2015 10:44,
cma-l-request at mailman.commedia.org.uk wrote:
> > Send cma-l mailing list submissions to
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> > Today's Topics:
> >
> > 1. Re: AM community radio (Tony Bailey)
> > 2. AM community (fantasy office)
> >
> >
> >
----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Wed, 16 Sep 2015 08:08:07 +0100
> > From: Tony Bailey
<ravensound at pilgrimsound.co.uk>
> > To: cma-l at mailman.commedia.org.uk
> > Subject: Re: [cma-l] AM community radio
> > Message-ID:
<55F91557.6000009 at pilgrimsound.co.uk>
> > Content-Type: text/plain; charset="iso-8859-1";
Format="flowed"
> >
> > Ian et al,
> >
> > I've only ever used a 1 watt (just about) setup
for AM RSLs and that
> > typically had to be running 15 Watts at the tx
output valve. I've seen
> > bigger amps used but we had various antennas
including a steel
> > telescopic mast, aluminium tube vertical, plastic
drainpipes and a T
> > wire. The latter worked well with a 150 ft
counterpoise earth running
> > about 450 mA aerial current. Reports from more
than 50 miles but the
> > effective local coverage was around 3 miles in
practice.
> >
> > Running my AM spreadsheet calculator it gives for
comparison purposes
> > the 66 dB contour at 2.5 km (1 watt); 5 km (10
watts); 8 km (70 watts).
> > The last two probably equate to tx powers of 150
watts and 1000 watts.
> > I would think it might be worth pointing this out
to prospective
> > licensees as there is clearly a significant
cost/benefit issue here.
> >
> > Regards, Tony
> >
> >
> >
> > On 15/09/15 17:10, Ian Hickling wrote:
> >> Phil
> >> I'm not denying at all that AM has its
advantages and uses - and
> >> believe me I wasn't being negative - just very
down-to-earth practical
> >> We've run AM RSLs with a guyed 18m pole with a
top hat - and we have
> >> one CR running with the ?3500 classic Radica
hinged plastic flagpole
> >> antenna.
> >> But we're talking here about a minimum ?15,000
investment a for a
> >> 5-year contract with the absolute requirement
of being able to sell
> >> lots of airtime on a robust reliable signal.
> >> So - if you can produce a 1kW transmitter that
will perform to Ofcom's
> >> satisfaction and an ATU that will handle that
- you have a customer
> >> sitting here waiting.
> >>
> >> *Ian Hickling*
> >> Partner
> >>
> >> <http://www.transplanuk.com/>
> >> /Office: 01635 578435 (7am-11pm UK time)/
> >> /Carphone: 07530 980115 (only responds when
driving)/
> >> /6 Horn Street, Compton, NEWBURY, RG20 6QS/
> >>
> >>
> >>> Date: Tue, 15 Sep 2015 13:52:18 +0100
> >>> From: office at fantasyradio.co.uk
> >>> To: cma-l at mailman.commedia.org.uk
> >>> Subject: [cma-l] AM community radio
> >>>
> >>> Afternoon all,
> >>>
> >>> For what it's worth, my own experience
with AM is that you can get some
> >>> astonishing results! For several RSLs I
have used a wire antenna, (an
> >>> inverted L) to great effect. The Earth mat
consisting of wire netting
> >>> laid on the ground. Height is might as
always, but even with only 20
> >>> metres, we were getting into Europe! I
have reception reports to prove
> >>> it. I have also used a single 1 1/4" tube
steel mast, with a 'top hat'
> >>> to increase top capacitance. I believe
Radica used to do AM antennae
> >>> using a lamp post. (you can get a lamp
post for about ?300) The
> >>> standard RSL AM licence is for 1 watt.
This gives a similar coverage to
> >>> FM at 25watts. Oh yes, and I designed and
built my own transmitters,
> >>> using valves!
> >>>
> >>> Within the specified 5km radius for
community radio, AM will do the job
> >>> nicely. (very important to get some good
audio processing though) Also,
> >>> with fewer stations now on AM it could get
better!
> >>>
> >>> Anybody want to know more? mail me at
phildawson at lemonmail.co.uk.
> >>>
> >>> Phil Dawson
> >>> FANTASY RADIO97FM
> >>> Devizes
> >>> Wiltshire.
> >>>
> >>>
> >>>
> >>>
--
Local Reports at http://www.ravensound.pilgrimsound.co.uk
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