Re: LF: AM on 472kHz

[Chris Osborn <g3xiz@yahoo.co.uk>]

AM on 472 KHz

There has been some emotive discussion about the use of AM on the 472 kHz band.

In the first instance I must admit to having used AM on that band for local QSO's and for test transmissions.

I have been running 5 watts of RF into my inverted 'L' aerial: length 43m, height 10m
Assuming that my field strength is not dissimilar to the measurements I made on 502 kHz then my ERP was in the order of 50 mW.
The total sideband power with 100% modulated signal would be 25 mW - I run at only 50% modulation.

For several consecutive evenings I have put out 'test' transmissions on 475 kHz giving my station call sign and locator and asking for signal reports.
Apart from a select few local stations who were specifically listening the only other station having reported hearing me was G3XDV, some 20 miles distant.

The NOV does not stipulate that AM is not permitted in the MF band and of course the only QRG suitable must necessarily be mid-band.

I find it inconceivable that with such  low radiated power levels any amateur could cause interference to a commercial transmission.
In that unlikely eventuality then the offending station would be identified and shut down.

Regarding interference to other amateur users on the band:

Having been one of the most active amateurs on 501-504 kHz I am aware of just how difficult it is to even 'hear' many stations on MF.
Furthermore no amateur worthy of the name would wish to cause QRM to his fellow users.

What then is the objection to the use of  low power AM on MF ?

I shall of course and as always adhere to my license conditions and official "gentlemen's agreements" regarding band plans.

73

Chris G3XIZ

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From: Roger Lapthorn <rogerlapthorn@gmail.com>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Sent: Saturday, 5 January 2013, 19:45
Subject: Re: LF: AM on 472kHz

Pete,

Honestly, is this helpful?

I have a lot of respect for Mike and others like him, and this sort of attitude is totally uncalled for.

73s

Roger G3XBM

On 5 January 2013 18:46, M0FMT <m0fmt@yahoo.co.uk> wrote:

Hi Mike

 

We know the RSGB owns the spectrum and want to control every issue to do with it like they messed up VHF particularly 4m with their policemen making life for anyone without the £5000 pound rig advertised in the RADCOM not welcome if your centre frequency was not with a few cycles on the channel.

 

Your e-mail to me a while ago about my paltry 50watts on 136,  but I never complained about your 1000watts that flattened signals I wanted to listen too on the band. So why do the pigeon whole brigade, with nice neat lists that have have entry  numbers, of things that can be done and can't be done the policeman's charter that makes other peoples life a misery with "I'm alright jack" attitude and limits experimentation. These may not be of the PhD variety but are of the self training variety which is the Amateur radio licence variety.

 

I don't give a toss about the RSGB 's rules and I will use the spectrum within sensible limits how I want and in line with what is in my licence.

 

You are an RSGB policeman just like the crowd on VHF! clagging the bands with repeaters and all sorts of junk and have the cheek to complain when a real radio amateur wants to do some off the wall tests that with in the acres of empty spectrum  on VHF people who you never hear in qso suddenly come up and say you can't do that here it's what your numbered lists policies create.

 

 And now you are doing it on 472/9. Sorry but its bonkers you are creating clones out of radio ops who you don't want to trust with the spectrum but its not your spectrum....... and in any case things have changed in the world and I don't think people will stand for Diktat as they might have done in the passed.

 

So long as us amateur stay inside the band limits and our EIRPs are sensible that is all authority is expecting us to do and what else we do I don't think they care about provided its not mischievous. Also my guess is they will tolerate the odd transgression without comment unless it is taking the Mickey out of our contract (the licence).

 

I would say cool the Captain Blimp approach and rub along with things and they may not turn out to be as bad as you think. Alternatively some of us who are fed up with lists with numbers will migrate out of amateur bands and do our own thing like quite a few are doing, ever listened at the ends of 80m 40m 20m etc there's a parallel universe of amateurs, even though getting a licence is a doddle these days.... why?

 

Just get real and rub along with what people want to do, you will hardly notice a bit of AM, like the RSGB call sign isn't it GB3FUN?

 

And if my electric bill could stand it I would probably run a KW like you using an old Decca commercial TX with its whiskers ever looked at an SDR waterfall? My 5watts tube tx a real threat?

 

Mike I won't apologies for the forgoing but I don't want to fall out with anyone however it cannot be a one sided argument and Diktat and toys out the pram is not the way to go, an arm round the shoulder does more than any amount of "Laws" and lets face it no one will be hurt (unless you put you fingers in that KW PSU you use on 136?).

 

Best regards 73 es GL es HNY Pete M0FMT IO91UX

From: Mike Dennison <mike.dennison@ntlworld.com>
To: rsgb_lf_group@blacksheep.org
Sent: Saturday, 5 January 2013, 17:13

Subject: LF: AM on 472kHz

Making a complete mockery of any attempt to persuade users of
different modes to coexist responsibly, an AM QSO is now going on in
the middle of the band!

I give up!

Mike, G3XDV



 

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