it used one of those big pll’s maybe an mc145152p2, I know years ago there were smart kits and they weren't very good, the 1w and 4w didn't work at all, the interview with the engineer made me think of the type of kits you could get in magazines, db bulluck? don't exactly remember the name, was another they had, a power oscillator, 3w transmitter you could get, you would get 2 big thick mains leads wires in the kit cut to 50cms each you were meant to use as an antenna, the two transistors worked as the oscillator and rf amplifier at the sametime it almost certainly never worked at all or would be outside the fm band, mostly they would sell dj equipment, I guess noone out there got these things to work or they never got used in a real pirate station, the engineers could of used the parts, maybe Pyers.

https://www.smartkit.gr/pll-fm-synthesizer-m.html

Your link doesn't work! I think that I know the kit you mean...It used one of the big Motorola PLL chips and a prescaler to get the oscillator frequency divided down to a frequency that the Motorola CMOS IC would be able to handle.

The IC was a very good device (for its time) and had a reliable lock detector output. However, it used up a huge amount of board space, and when it was current, it cost a fortune!

The "Smart" stuff was - frankly - rubbish. It was poorly designed, and they bought the cheapest components they could find (in most cases). They tried to copy some of the "Josty" and "Amtron" kits, which suggests that they were not actually engineers, and the "Smart" versions were always inferior!

The only kits that were any real use were the NRG ones - discontinued now because of the demise of Stephen Moss, and the FRB ones from California. Stephen Dunifer's boards are of good quality, the designs are first rate, and the components supplied are of good quality. The kits presuppose that you're able to solder competently, can read and understand circuit layout diagrams, have the basic tools and test equipment you'll need, and an understanding of the principles involved.

Building a transmitter isn't trivial, and if you don't understand fully what you're doing, your chances of success are small. You need basic test equipment, tools, somewhere to work with plenty of light (and ventilation - solder fumes can be detrimental to health), and some understanding of the underlying theory and principles.

Unfortunately, the Pirate Radio game has an inordinate number of solder-jockeys who claim to be engineers, but have no proper understanding of electronics and usually lack the real skills to do a good job. It's like getting your mate who polishes his car every weekend to try to diagnose a fuel injection fault on a V8 engine. It's seldom going to go right!

If you want to learn how to design and construct competent equipment, you need to start small, with a couple of really basic electronic projects, and do copious amounts of reading too. You'll also need a rudimentary grasp of mathematics, and an ability to do at least basic algebra. You'll have to get hold of the right tools and instruments, You're going to need (amongst other things) a reasonable quality multimeter, an RF bridge, a dummy load, a bench power supply, a frequency counter and - at least - a calibrated absorbtion wavemeter. These will get you started. You'll have the means to see if your creation is on the right frequency and if it's producing outputs that it shouldn't.

When we were kids, we made little two-transistor, voltage-tuned rigs that were built into the centre box of a VHF receiving aerial. They were powered up their coax, and the modulation was added to the supply voltage, deviating the frequency of the rig. If constructed carefully, using the right components, they were ridiculously stable despite their simplicity. We'd install them on the rooftop TV mast on our houses, and it was possible to be heard over several kilometers! They were great fun, and the way that a lot of us got into illicit broadcasting!
I'll see if I can find the details to make one.....

I've used the MC145152, plessey sp8793 prescaler and a tl071 in the past, they worked well not only on the fm 88 -108mhz but for link transmitters on band 1 & 3.

As albert says they were expensive at the time from memory both ic's were around 15 quid each, i have a stack of new old stock motorola MC145152 & plessey sp8793 that are unlikey to ever get used as there's alot of cheaper options these days.

I think this is the old rooftop classic what Albert is talking about.

I build couple as kid, and it works.

That's pretty similar to the ones we used to make! Mine didn't have any trimmer capacitors in them - I used fixed silvered-mica capacitors instead (for stability), and they were tuned by screwing brass screws in and out of the coils. You could get them to tune over about 1½ MHz by varying the supply voltage, so they were "remote tuned". My power supply for them used a 723 regulator IC and a small plastic power transistor (BD131, I think). The power supply / modulator was built into a small diecast box, and operating the thing was quite amusing:

About 15 minutes before the start of programmes I'd tune my receiver to a gap around 106 MHz, then fire the rig up, and turn up the voltage until I heard it! The frequency would drift a little as the transistors heated, so a small tweak to the supply voltage was always necessary after a few minutes (before programmes started). The "modulator" was a little 8 Watt transistor audio amplifier that I built from a magazine article, which was also housed in a diecast box. It had a preamplifier stage that added pre-emphasis, too. Later, I added a simple limiter to prevent over-deviation.

Considering the simplicity of the system, it worked really well. Over a 4-hour broadcast, the frequency might move around 5 kHz, which was remarkable! My little station got reception reports from as far away as 45km. From the supply voltage and the current drawn, I would estimate that the output power was around 1500 mW at most.

We did drive them straight from cheap bench power supply, just adjusting voltage to stay on frequency, audio was just stolen from old casette player speaker.

Rain, birds etc landing on antenna made it to dive under whole FM band, on winter it might start on air band, and when it did heat up, slowly drift back to FM band.

Someone did sell these as kit, I dont remember who. It was so expensive that we just build our own.

i have 1 , i can take picture to them later , for nostalgic purposes Only. My first transmitter was a smart kit and was expensive for 15W bly88c , at first start i blow the driver stage 2n3924 and the bly , cause i reversed the ps , have a good sound , and i make it drift about 0.25 (25khz) vfo , with a good ventilation and just sized metal box and good meanwell 12V/5 A power supply , but was awfull , to tune stage , and you have to take care of the 7 trimmer vishay philips , after time i discovered that they copy their kits . i also copied from the greek itself the stereo coder and the 3W vco and i have assembled the pll , having U893 replaced by U664 prescaler division factor 64 , my aerial was a ground plane , that i paid a fortune for it , in that decade 25 years ago .Love that nostalgie.

I remember that a bloke that I used to know had one of those BLY88 "15 Watt" rigs, and asked If I could make it work properly for him.

After examining it for about 2 minutes, I decided that there was no way to make it work properly, so I stripped the board for the parts, and built him a nice little rig out of the parts, and added quite a few too. I gave it a PLL (just my usual 5 IC diode programmed job running at ½f), and a four stage exciter (using 2N2369 transistors - BSX20 equivalents). The PA ended up being an under-run 2N4427 into a 2N6080 then into the BLY88, since the 2N3924 didn't have enough "go" to drive the BLY88 properly.

When completed and tuned, it did a little over 18 Watts with a fully charge car battery. I gave it a reasonably generous heatsink, and the exciter was in a little tinplate box to screen it from the rest. The whole thing was fitted into a folded aluminium box (an H. L. Smiths special!).

He ran that rig on Sundays for a couple of years from field sites in Surrey, and it got into South-West London really well, using a 3-element Yagi. He had four stacked auto-reverse car cassette decks to play out the programmes, and he used to use C90 cassettes for a six-hour broadcast. There was a big relay (a car headlamp relay) that was used to turn everything off when the last tape finished.

Love this .@Albert , a quick question , as you may know well the nrg kits era , afterthe experience of you , do you remember well and can gave a bit of technical storie , of about if the stereo two channel compressor limiter was a good to so loud audio that really amplifiy quiet and decrese high level , with no or near no overshoot modulation deviation of 80Khz .

lol I was just trying to work out why the antenna in 1 watt fm zender picture isn’t connected to ground, someone likes buzzing an awful lot