Medium And Long Wave Hobby / Frree > Pirate Radio in the UK

[montaylor]

was picking up 1575 this morning

[Albert H]

The beauty of the lower frequencies is that gear is much easier to build. The simplicity of an AM rig is lovely to see - my first MW rig (back in 1969) used just three valves, and developed around 7 Watts carrier / 25 Watts peak. Most of the components were scrounged by breaking up old radios and TVs. We used an inverted-L antenna, and used the water mains for the earth. It went for miles!

Back in the 80s, I started to build simple AM rigs using semiconductors. We began to use quarterwave wire aerials from the top of tower blocks, tied off to lamposts or trees using fishing line for insulation. The most expensive part of the whole enterprise was the wire for the aerials! We earthed the rigs to the lightning rods on the buildings, and got spectacular daytime coverage despite only running about 30 Watts peak. Later rigs - with bigger switching FETs (as they became cheaply available) got very much more powerful. It's possible to build a kilowatt-class rig using just £12 of FETs!

All the early rigs used "anode" modulation, but as the power increased, this became increasingly difficult. I had to find alternative ways of generating an amplitude-modulated signal:

I tried low-level modulation, followed by linear amplification, but this was just as inefficient as simple Anode Modulation. I tried the "Ampliphase™" system with some success: You generate a pair of carriers from a common frequency source, with one of them offset (under no modulation) offset by 135°. These two carriers are then separately phase modulated - in opposite directions - and fed through two identical power amplifiers (that don't have to be linear, so can be efficient). The two carriers are then combined in a bridge arrangement, with one corner of the bridge going to the antenna, and its opposite corner going to earth. The phase additions and subtractions by the mixed phase-modulated carriers cause AM at the aerial terminal. This makes for a more complicated rig, but the efficiency can be >90%.

My most recent designs use another kind of "outphasing" scheme, which uses fast comparators to give PDM (Pulse Duration Modulation) of the carriers, and Class D or Class E power amplifiers which are trivially combined in a network much simpler than needed for Ampliphase™. Using cheap, but powerful higher voltage FETs, it's easy to generate considerable power.....

[Zozo]

I think the few that have attempted MW particularly on this forum have some difficultly in assembling an antenna system that's able to radiate a reasonable signal. FMEnjoyer mentioned the base loaded vertical which I have highlighted previously on here. Also I think some of the TX's used are those from Vintronics / SJV ?? These as I recall are designed to feed directly into Hi-Z wire antenna, personally you want a TX with a 50Ohm system impedance, you'll then be able to feed a vertical antenna with coax which is at-least resonate despite it's less than ideal efficiency.

This website by 66Pacific will give you all the information to build a Vertical antenna. https://www.66pacific.com/calculators/c ... lator.aspx

Below is the design drawing I originally posted some time ago using a telescopic fibreglass pole with just a wire as the antenna and a coil at the base. However I did find in pratice this antenna is more suited to an open space site that has no structures or obstacles close by. You could even use this on a tower block with the bare minimum of radials in X plain configuration.

LPAM.png

Here is the last coil I made on a white 35mm domestic waste pipe, it has 85 turns and an inductance of 156uH as I recall. I think I use 2mm core wire as the antenna. I just fixed the wire to the tip of the final telescopic section and as I extended the pole I introduced a couple of twists of the radiation wire around the pole to keep is from flapping around.

IMG_0932 2.jpg

[FMEnjoyer]

Albert your knowledge and work is masterful as always. Zozo I respect what you are doing 100pct. My knowledge, bits and bobs amounting to very little but quite enthusiastic when I fancy.

I think it quite easy to make a big coil and 12m or more of wire going up a flag pole for a temp garden install anyway. You would need as many radials as possible of as long as you can in as many directions as you can that would help a lot actually. Again lots of work though and maybe even in a 15m garden a few 100m of wire on the deck coming from your ground/neg side, which is attempting to be loaded shortened 1/4 wave.

I cannot vouch for how well it would work.. at best guess a 8 inch tube would need to the order of 40 turns of copper wire on it, use 1.5mm enamelled copper for up to 100W or so, use copper and 1.5mm for a little better efficiency than 1mm . Don't make that though it is an extremely crude guess. Look up a 160m band 1/4 wave and a few more turns and a bit longer vertical will do it to drop it down from top band ham band into MW. The more radials and longer you get down the better end of story on that.

It is only know I see your images after logging in.

An 1/2 wave 80m long dipole would be great but it would be difficult to get high, attached at both ends and fed in the middle, a big ask and even at 30m which would be a big ask, and need 2 attachment points exactly 80 m away from each other it would be a fraction of a wavelength and it would still be an NVIS antenna... so could work very will for Europe night skip.

So verticals and the L antenna make a lot of practical sense.

When I can get my MW reception sorted out I will have a more of a listen I like the Dutch pirates but for now not possible.

And I am not suggesting don't be on air by the way, do exactly what you want that is what pirates do after all right ? I just meant that extremely few who, that you never told you were going to be on, would have stumbled on it. Though more now on here probably.

I might try down the garden and see if the interference drops off. It might just be indoors, it is nothing indoors in my own place as far as I know.

Good luck.

[shuffy]

I think the few that have attempted MW particularly on this forum have some difficultly in assembling an antenna system that's able to radiate a reasonable signal.

Definitely, the ground is crucial and I've always found that to be the part that requires the most effort. Thanks for the info and links Zozo, will definitely consult if I have another go at AM.

[EFR]

I have done some MW stuff, simple Marconi T antenna, high as possible, I have had luck with some tall pine trees, wide as you can get.

For radials, just couple wires from feedpoint, and power TX from grounded mains outlet.

Just trow about 2000-2700pF 10kV capacitor from coax center to ground, around 2uH coil from center towards antenna and 2000pF variable from it to the antenna.

4 about 30m long radials is enough to start.

And as we all know, when trees grow, antenna gets higher

[surefm]

Radio Blackbeard Now Transmits On 1476 mw

[Nige from Brum]

I've been getting out a couple of miles with the "1 watt" SJV transmitter. The aerial is approximately 16 meters of wire spiraled round an 8 meter fishing pole. I have 4, 1 meter ground rods and then 3 radials running down our small garden. The aerial isn't exactly well matched, but it does get out. I have built the ZoZo MW rig and compressor, I just need to get round to building a loading coil now.

[radionortheast]

Radio Blackbeard Now Transmits On 1476 mw

There was radio blackbeard I heard on thursday night, I could hear every song, there was constant fading, I had dutch stations on 1620,1629,1638,1647,1656 the other night playing nice polka to dance around too.

The music on blackbeard was like every song I played through 30 in 1, 300 in 1, am transmitter when you tune off to the side to get high frequencies, can’t of been the only one playing the whole 2unlimited album through this. Good luck radio b bird anyway

[David2999]

As this is a very wide read and popular Free radio forum, how do the members here feel about our gaining access to the MW band? As we are talking MW, only public broadcasting has ever happened there, and there is no UK law saying we cannot access MW now on a strictly "secondary shared basis". We are in "Region 1", and that's where MW is abandonded. Therefore, as there is NO legal or logical reason why we should not now use MW, (provided transmissions are non political, non commercial (no adverts) or controversial in any way). I feel the time is right to do Free Radio in the MW band, as is permitted (or openly tolerated) in several other countries. It was Mike that raised the fact MW will soon be totally abandoned and disused. I feel Ofcom cannot supply ANY sensible reason why our access to MW cannot now happen. What are your thoughts (as Free radio enthusiasts) on this way to take our interest in Free radio forward, as the methods of UK media delivery are today expanding rapidly into the online digital and smartphone platforms?

[marqueemoon]

i have an 8 watt rig but its way harder than FM to make up an aerial for it I find I am going try join to really long wires up some time see if it goes better.

You're not kidding... I've got one of those Spitfire 100mW transmitters, and there was no way I could get the signal to radiate more than two feet with the stock (bit of wire) antenna. No science was applied, but 4 bits of scrap copper pipe were bodged together by sawing their ends lengthways, hammering them together and securing the resulting mess with hose clips. Total length of this atrocity is about 10ft... I tie wrapped it to the downpipe at the back of the garage and now I get a decent signal throughout the house. You have to walk about 6ft into the road before it starts to break up, so I'm calling that a win

I hasten to add that the purpose of all this isn't the benefit of other listeners, but so that I have something to listen to on all my old radios (mostly Soviet portables) that aren't blessed with FM!

[jvok]

You want distance on MW you need a good ground. Some wires buried under the grass in the yard will work. Makes more difference than a bigger antenna.

[marqueemoon]

You want distance on MW you need a good ground. Some wires buried under the grass in the yard will work. Makes more difference than a bigger antenna.

Yeah, that was the first thing I did... bought a cheap earth spike and wacked it a good 4ft into the ground. Unfortunately the supplied antenna was still useless, which led to me building the hideous - albeit effective - creation that I'm using now.

[fmuser877]

I have put 3 rods in my garden all its done is seem to make less hum but no more range.

[yellowbeard]

For better results you'd need to antenna and ground to be resonant - a fat tapped coil at the feed point and a capacity hat on the top is your friend. If you search for LPAM antennas there are good resources to be had, they are not as efficient as a full sized set up and need extra tuning and setting up - but resonating the antenna will definitely help.

[marqueemoon]

I have put 3 rods in my garden all its done is seem to make less hum but no more range.

Yeah, it definitely improved the level of hum for me. However that only applies to battery powered sets... mains powered ones have a really horrible buzz present for some reason. It's not a deal breaker anyway, as I would listen on FM using those.

[jvok]

I have put 3 rods in my garden all its done is seem to make less hum but no more range.

I found rods never made much difference, you need radials. You want metal horizontally on/near ground surface, not going vertically into ground.

Basically what you need for AM is good ground conductivity around the aerial. Rods will give you a better connection to the existing ground but doesn't really help if that ground isn't already conductive (and even wet soil isn't that good). By putting in radials youre making your own "fake" ground out of metal instead

[radionortheast]

It was a novelty, making thoses low power am transmitters you’d beable to make with a 30 in 1 or 300 in1 kit, hearing it come through in another room, they sounded nice if you tuned off frequency. There was nothing much on am apart from radio 1, in 1994, all the pirates interesting stuff was on fm, different for some people were around ealier, it was impossible to get those things to go much further than a house, I started on fm instead which was easier to get out, even with local oscillators you could hear the signal in nieghbouring houses very well, get it to go abit down the street. Does seem abit of backwards step to go onto am knowing it can't be done, i've not really much interest in doing fm, even less for am.

A low powered signal on fm of only a watt with an indoor aerial can be heard clearly a mile away, be listened to on a car radio, even in mono has higher frequencies you’d get with am, much easier to take else were like on hoilday, have something without much messing. With am its impossible to do the samething, even with using the mains instead of a wire indoors with 4w, results were only a weak signal could be a mile away on a pocket radio, (the closest you’d get to some underground antenna) it could be listened to when the engine was switched off in the car. Think the idea that could be like fm could beable to have something you could hear a few miles on a car radio unlikely.

Radio brittania always had a good signal on fm, when he moved to am later on it life, even though he’d buried all this stuff in the garden by the look of it, it only came over very weak on am if there at all, if someone who knew what they were doing couldn’t make it work, I don’t see how anyone else could do it. If people wanted to do it something they like doing, they get something out of it, I wouldn’t stop them. 4 8w transmitters think they more like toys, probably sold knowing noone will get beyond afew 100 meters.
Might be better someone to get the ones that are strapped to the pole, I suppose will be resonate even its short, might get a few 100 meters I suppose you won’t beable to listen to in a car miles away, I think that makes this abit of a none starter. Access to the airwaves is good, don’t think its practical on mw frequencies, should be provided at fm frequencies when more stations close down.

[87to108]

I have put 3 rods in my garden all its done is seem to make less hum but no more range.

Yeah, it definitely improved the level of hum for me. However that only applies to battery powered sets... mains powered ones have a really horrible buzz present for some reason. It's not a deal breaker anyway, as I would listen on FM using those.

the mains power sets have a bridge rectifier in the powersupply.
RF passing through that gets amplitude modulated at 100Hz (50Hz X 2).

You could try using a mains filter just prior to the receiver

[David2999]

Sent to Ofcom and the RSGB:-
Hi All.
Because Ofcom still FAILS to answer the simple question "What is the future of the obsolete L & Medium broadcast bands
in the UK?", we should now regard Ofcom as some sort of computer driven "quango programme" that cannot answer a simple
direct question in a sensible way, but can only regurgitate pre-programmed responses that are of no use to anyone these days.
We ALL know broadcasting using radio is now dead in the UK, as is proven by no radios now being sold on the High Street. .
We are also now bombarded by UK TV adverts showing people sniffing each other's balls, crutches and asses.
What is Ofcom (the SUPPOSED UK media content regulator) doing about that?
Ofcom, the "quango computer generated programme", has NOT been "detailed" how to respond to thatEmoji, so Ofcom, of course,
does NOTHING.
This will be copied and posted on pirate and free radio forums as VALID reasons to do pirate, ham and free radio as we wish
in any unused radio spectrum.
With very kind regards, David Hine G4DIG..