[cma-l] community AM

Thu Sep 17 11:08:21 BST 2015

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
>
> <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/
>
>
> > 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:
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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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