[cma-l] AM community radio

Wed Sep 16 08:08:07 BST 2015

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
> > >
> > > To subscribe or unsubscribe via the World Wide Web, visit
> > > http://mailman.commedia.org.uk/mailman/listinfo/cma-l
> > > or, via email, send a message with subject or body 'help' to
> > > cma-l-request at mailman.commedia.org.uk
> > >
> > > You can reach the person managing the list at
> > > cma-l-owner at mailman.commedia.org.uk
> > >
> > > When replying, please edit your Subject line so it is more specific
> > > than "Re: Contents of cma-l digest..."
> > >
> > >
> > > 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
> > >
> >
> > _______________________________________________
> >
> > Reply - cma-l at commedia.org.uk
> >
> > The cma-l mailing list is a members' service provided by the 
> Community Media Association - http://www.commedia.org.uk
> > Twitter: http://twitter.com/community_media
> > http://www.facebook.com/CommunityMediaAssociation
> > Canstream Internet Radio & Video: http://www.canstream.co.uk/
> > _______________________________________________
> >
> > Mailing list guidelines: 
> http://www.commedia.org.uk/about/cma-email-lists/email-list-guidelines/
> > _______________________________________________
> >
> > To unsubscribe or manage your CMA-L mailing list subscription please 
> visit:
> > http://mailman.commedia.org.uk/mailman/listinfo/cma-l
>
>
> _______________________________________________
>
> Reply - cma-l at commedia.org.uk
>
> The cma-l mailing list is a members' service provided by the Community Media Association - http://www.commedia.org.uk
> Twitter: http://twitter.com/community_media
> http://www.facebook.com/CommunityMediaAssociation
> Canstream Internet Radio & Video: http://www.canstream.co.uk/
> _______________________________________________
>
> Mailing list guidelines: http://www.commedia.org.uk/about/cma-email-lists/email-list-guidelines/
> _______________________________________________
>
> To unsubscribe or manage your CMA-L mailing list subscription please visit:
> http://mailman.commedia.org.uk/mailman/listinfo/cma-l

-- 
Local Reports at http://www.ravensound.pilgrimsound.co.uk

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.commedia.org.uk/pipermail/cma-l/attachments/20150916/4686240f/attachment.html>