I'm still building and selling around 100-200 SW A.M. transmitters a year.
Class E RF and Class D PWM modulation, single PLL OSC or prog DDS.
Small and efficient, 10W will fit in a shirt pocket, needs 24V@2A.
ANY frequency from 0.5 - 8MHz.
I'm also building a 100W version, somewhat more of a serious affair and will be ready soon. Lots of clients have asked for this...
SW AM is still fairly popular, main sales 90% are to E coast US, with the rest to every other country, maybe not CH but quite a few to RU!
I'm busy trying to 'popularise' MW AM as it's so under used and you can cover a decent size town / small city with 10W and a 50' vertical.
Have one client who transmits 'Sonic Art' which is quite funky and sounds really spooky on SW.
Pirate radio will never go away and despite the internet there's still plenty of users out there and with the plethora of online SDR's it's easy to listen.
I'm still building and selling around 100-200 SW A.M. transmitters a year.
Class E RF and Class D PWM modulation, single PLL OSC or prog DDS.
Small and efficient, 10W will fit in a shirt pocket, needs 24V@2A.
ANY frequency from 0.5 - 8MHz.
I'm also building a 100W version, somewhat more of a serious affair and will be ready soon. Lots of clients have asked for this...
SW AM is still fairly popular, main sales 90% are to E coast US, with the rest to every other country, maybe not CH but quite a few to RU!
I'm busy trying to 'popularise' MW AM as it's so under used and you can cover a decent size town / small city with 10W and a 50' vertical.
Have one client who transmits 'Sonic Art' which is quite funky and sounds really spooky on SW.
Pirate radio will never go away and despite the internet there's still plenty of users out there and with the plethora of online SDR's it's easy to listen.
Cheers to ALL..
Str.
Great post Stretchy.
What would you say is the attraction of AM broadcasting? I understand what you say about distance but I would imagine there are even fewer listeners on MW/SW than on FM. So broadcasting 100 miles doesn't mean more listeners...there must be more to it!
And what about the content being broadcast...is it generally different to FM?
As a dyed in the wool FM fan, I want to be educated!
What would you say is the attraction of AM broadcasting? I understand what you say about distance but I would imagine there are even fewer listeners on MW/SW than on FM. So broadcasting 100 miles doesn't mean more listeners...there must be more to it!
And what about the content being broadcast...is it generally different to FM?
As a dyed in the wool FM fan, I want to be educated!
In larger cities or living near them there usually isn't any room on FM. Every frequency is either in use by the big watts or the translators, and yeah there is the option of 87.9MHz and 87.7MHz but you'll stick out like a sore thumb.
AM has more technical challenges which can be intriguing to to hardcore hobbyists. Antennas can be harder to tune up but have the benefit of being well hidden since you can run a piece of wire up a barn or out to a tree. Laying ground radials is usually the hardest part.
FM pirates are busted far more often. Of course there are far more FM pirates, but it does seem to take more time for localized agents to track down AM pirates, or especially SW pirates because of skip unless the big guns get involved.
Finally there is the fact that FM simply doesn't penetrate buildings or hilly terrain well without a lot of broadcast power or circular polarized antennas up very high since you will have people using all sorts of different receiver antenna contraptions. Your main audience will be car radios for this reason. Mediumwave offers the possibility of getting through hills and into all sorts of buildings, and listeners of the AM band often listen to their indoor radio during prime hours.
Also lets not forget skip which can be a lot of fun with HF and below including the AM broadcast band. With dozens to hundreds of watts you can be heard hundreds to thousands of miles when conditions are favorable. Lets face it too that getting that sort of power is easy with cheap parts on low frequencies, whereas on VHF and the FM broadcast band RF amplifiers and part prices climb rapidly with higher power levels. Put it simply.. AM is cheap, proven, and fun
What would you say is the attraction of AM broadcasting? I understand what you say about distance but I would imagine there are even fewer listeners on MW/SW than on FM. So broadcasting 100 miles doesn't mean more listeners...there must be more to it!
And what about the content being broadcast...is it generally different to FM?
As a dyed in the wool FM fan, I want to be educated!
In larger cities or living near them there usually isn't any room on FM. Every frequency is either in use by the big watts or the translators, and yeah there is the option of 87.9MHz and 87.7MHz but you'll stick out like a sore thumb.
AM has more technical challenges which can be intriguing to to hardcore hobbyists. Antennas can be harder to tune up but have the benefit of being well hidden since you can run a piece of wire up a barn or out to a tree. Laying ground radials is usually the hardest part.
FM pirates are busted far more often. Of course there are far more FM pirates, but it does seem to take more time for localized agents to track down AM pirates, or especially SW pirates because of skip unless the big guns get involved.
Finally there is the fact that FM simply doesn't penetrate buildings or hilly terrain well without a lot of broadcast power or circular polarized antennas up very high since you will have people using all sorts of different receiver antenna contraptions. Your main audience will be car radios for this reason. Mediumwave offers the possibility of getting through hills and into all sorts of buildings, and listeners of the AM band often listen to their indoor radio during prime hours.
Also lets not forget skip which can be a lot of fun with HF and below including the AM broadcast band. With dozens to hundreds of watts you can be heard hundreds to thousands of miles when conditions are favorable. Lets face it too that getting that sort of power is easy with cheap parts on low frequencies, whereas on VHF and the FM broadcast band RF amplifiers and part prices climb rapidly with higher power levels. Put it simply.. AM is cheap, proven, and fun
I would say that about FM too! Though the fun factor is, as you say, inhibited by the higher risk of getting caught. AM certainly has the edge there.
Let's talk about range, penetration, cost and antennae.
AM range and penetration (of buildings/obstacles etc) is better than FM I get that. But cost I'm not sure about as I have no idea how much a decent AM rig would cost to buy. +/- $/£500?
But it's the antenna I dont get. Unless you live on a farm, how do you string up an antenna that's long enough to tune to your wavelength? I live in a flat. Can you imagine it? Not exactly discrete! Maybe there's such a thing as a compact AM antenna? I'm not aware of one.
And what about content? I imagine AM broadcasters tend to broadcast more nerdy type stuff like stretchy said or maybe spoken word or middle of the road music. In that respect it may be more interesting than FM which in London at least seems to be music heavy and stuck in the past with a selection of House, Jungle and Garage tunes that largely (but not exclusively) sound like they did 20+ years ago.
I'm still building and selling around 100-200 SW A.M. transmitters a year.
Class E RF and Class D PWM modulation, single PLL OSC or prog DDS.
Small and efficient, 10W will fit in a shirt pocket, needs 24V@2A.
ANY frequency from 0.5 - 8MHz.
I'm also building a 100W version, somewhat more of a serious affair and will be ready soon. Lots of clients have asked for this...
SW AM is still fairly popular, main sales 90% are to E coast US, with the rest to every other country, maybe not CH but quite a few to RU!
I'm busy trying to 'popularise' MW AM as it's so under used and you can cover a decent size town / small city with 10W and a 50' vertical.
Have one client who transmits 'Sonic Art' which is quite funky and sounds really spooky on SW.
Pirate radio will never go away and despite the internet there's still plenty of users out there and with the plethora of online SDR's it's easy to listen.
Cheers to ALL..
Str.
Do you have more details? Price, where to purchase, etc?
Re FM etc. FM is heavily policed due to potential REVENUE LOSS. No one cares about A.M. and even less SW. Your not going to be treading on anyone's toes!
Re material broadcast...I've no idea, ANYTHING goes!
My eBay ID is stretchyman2k.
Please don't bombard me with messages on there.
My email is either on the PCBs shown or on my T shirt in the 100W video, crafty eh!
Over here in Europe, the Medium Wave Band has cleared up a lot lately, as the huge French stations have closed down, so there's acres of space! AM can be more hassle in the aerial department, but you won't get chased like you will on FM! In the UK, the OFCOM (the "Feds" over there) largely ignore pirate operation on AM (unless you cause interference). In Ireland, COMREG seem to mostly ignore AM, and here in the Netherlands, we even have licenced low-power AM, and the Licences are cheap and easy to get.
The technology of AM transmitters is much simpler (and more forgiving) than that used in FM gear, and transmitters are easy to build. Way back, my first AM station used a self-oscillating 807 valve in a crystal-controlled "power oscillator" circuit, and I used an old guitar amplifier as the modulator! These days I build "ampliphase" FET-based rigs at various power levels.
Over here in Europe, the Medium Wave Band has cleared up a lot lately, as the huge French stations have closed down, so there's acres of space! AM can be more hassle in the aerial department, but you won't get chased like you will on FM! In the UK, the OFCOM (the "Feds" over there) largely ignore pirate operation on AM (unless you cause interference). In Ireland, COMREG seem to mostly ignore AM, and here in the Netherlands, we even have licenced low-power AM, and the Licences are cheap and easy to get.
The technology of AM transmitters is much simpler (and more forgiving) than that used in FM gear, and transmitters are easy to build. Way back, my first AM station used a self-oscillating 807 valve in a crystal-controlled "power oscillator" circuit, and I used an old guitar amplifier as the modulator! These days I build "ampliphase" FET-based rigs at various power levels.
What's cool is that a PLL with three chips (4066, 4046, and 40103) can be built for beer money and throw in a few IRF MOSFETs and a transformer for the modulator and you are on the air with 10-100+ watts easily. Of course that assumes the antenna isn't the most complex part, as we all know it is lol. Sound processing also makes the night and day difference too but luckily these days people can get away with using Stereotool if you don't have the outboard equipment, and I'd like to believe after I released schematics for a triband processor I designed that can be an option too for those inclined to build their own.
AM broadcast band really does have the reach if you can setup the antenna. A lesson I learned early on is if amateur radio operators can use 30-40' inverted L antennas and reach out hundreds of miles then it's not a stretch to move from 1800kHz to 1710kHz and reach peoples average car radio or boombox with the same distance. I proved it to myself last time I was on the air and had people a few hundred miles away listening at night and got logged only running two handfuls of watts.
We have an ex-pirate - Radio Caroline - licenced in the eastern UK with 1 kW on 648 kHz. Their signal isn't too bad, but gets flattened at night by a Spanish station and a Czech station, each running >100 kW. My place in England is just 8 miles from their site, but I really can't listen to them at night because of the interference.
Caroline also has a serious problem with their modulation - it sounds like it's coming through a sock! They're using some horrible Broadcast Warehouse processor, and it sounds dreadful! Later in the summer, I'm going to put on a very powerful signal - from a good site (on polder) - on 666 kHz (clear in northern Europe), and show them what good AM mod should sound like! I've got an old Inovonics 222 which I'll press into service. A lot of Caroline listeners will tune in to us by mistake, and most will stay listening because it'll sound much better!
Back in the days when Caroline had a really good transmitter engineer out on their boat, their Ampliphase rigs used to sound really good. These days, they're sounding dreadful.....
Incidentally - my temporary AM aerial lash-up is a vertical rectangular loop over my garden - 60' across, with 19' verticals. The 19' vertical at the house end is made from UR67, with the inner conductor driven from the rig, so it acts as a long transformer. The balanced feeds from the ATU are RG58, with the screens earthed at the ATU end. The far end vertical is broken at its lower end and a big variable capacitor resonates the loop. The lower horizontal is 8' above the ground, and the upper is horizontal 27' up. 25 Watts carrier, 100 W peak gives me around 80 miles on 1602 kHz in the daytime to a car radio. The idea for the aerial came from a "Practical Wireless" article many years ago called "Looping Over The Lawn", and I was pleasantly surprised by the results. Initially, the "Q" of the loop was a bit high, attenuating the sidebands too much, but the addition of a resistor in parallel with the tuning capacitor mostly sorted that out. I applied a bit of pre-emphasis to the modulation, and it now sounds really good!
Later in the summer, I'm going to put on a very powerful signal - from a good site (on polder) - on 666 kHz (clear in northern Europe), and show them what good AM mod should sound like! I've got an old Inovonics 222 which I'll press into service. A lot of Caroline listeners will tune in to us by mistake, and most will stay listening because it'll sound much better!
Definitely do tell how you setup your audio and if possible some airchecks. I am always curious about the audio side of AM broadcasting since everyone has their own idea as to what sounds good. Up to you of course if you want to spill secrets of your audio chain.
Sad to hear about Radio Caroline. I figured they always had the best engineers being on the hobbyist side like us, but maybe they are just having some issues or temporary equipment. This is outside of my scope since I am in the US but I do enjoy any news I can get about their station and setup since it inspired so many over here too.
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