[cma-l] community AM

Ian Hickling transplanfm at hotmail.com
Wed Sep 16 20:46:02 BST 2015 

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:
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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.
> >>>
> >>>
> >>>
> >>> On 15/09/2015 12:00, cma-l-request at mailman.commedia.org.uk wrote:
> >>>> Send cma-l mailing list submissions to
> >>>> cma-l at mailman.commedia.org.uk
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> >>>>
> >>>> Today's Topics:
> >>>>
> >>>> 1. Re: AMCR - SDR (Associated Broadcast Consultants)
> >>>> 2. AMCR - SDR (Ian Hickling)
> >>>> 3. Re: Confession (Two Lochs Radio)
> >>>>
> >>>>
> >>>> ----------------------------------------------------------------------
> >>>>
> >>>> Message: 1
> >>>> Date: Tue, 15 Sep 2015 10:33:45 +0100
> >>>> From: Associated Broadcast Consultants <info at a-bc.co.uk>
> >>>> To: The Community Media Association Discussion List
> >>>> <cma-l at mailman.commedia.org.uk>
> >>>> Subject: Re: [cma-l] AMCR - SDR
> >>>> Message-ID:
> >>>> <CAG9-nrYO5ZHtH6B54QmMBYS1VZqzLaSJD39dX4W_jqJ_g95C3A at mail.gmail.com>
> >>>> Content-Type: text/plain; charset="utf-8"
> >>>>
> >>>> If anyone is interested I have Software Defined Radio for sale on
> >> Ebay at
> >>>> the moment. I've used the same type of unit to run a DAB test
> >> multiplex.
> >>>> I'm pretty sure I've recall that someone has already written the
> >> code to
> >>>> run it as a DRM transmitter.
> >>>>
> >>>>
> >> http://www.ebay.co.uk/itm/HackRF-One-Software-Defined-Radio-NEW-Unopened-FREE-Postage-BARGAIN-/271983417851?hash=item3f537999fb
> >>>> I can't help feeling though that the SDR is the "easy" part. The
> >> difficult
> >>>> part is getting an efficient aerial system.
> >>>>
> >>>> Glyn
> >>>>
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