How do you go about making a pll transmitter

[radionortheast]

Albert says its easy, seems to me it is quite hard to do, something that is quite easy to get confused by, no clear direction or method. I had quick look again, seems there are two pcbs available, one an nrg pll, the other less components and pic. I suppose what you’d want is something that has good immunity to rf, doesn’t buzz, that would go to a few watts, without complicating this too much, fairly east to tune, both of the pcbs have pros and cons which make it hard to decide.

There are circuits out there for PLL’s on the web, maybe no pcbs, maybe old, unlikely to work without a pcb, if there was the layout for a pll, that would do this, how you would go about getting a pcb printed, I suppose it would have to be in a special file type, go to a company, seems to me there is a lot ambiguity to it, something I don’t like, as I like to know exactly what to do, seems to involve a lot of unknowns, sends my head into a spin, maybe someone could explain that how they do that.

The pcb that users the pic could likely be got working easly with fewer components, rf immunity is unknown (I had a bad experience with another tx that wouldn’t stop buzzing) The nrg pll, it has alot of components, so more to go wrong but half frequency oscilator so high rf immunity. (alberts funny half frequency doubler) I was reading threads seems it needs the exact parts, seemed like radium had some problem but it ended up been a diode, wonder if anyone tested the one that users the pic.

[Albert H]

They way we used to build rigs was "dead-bug" style, over a sheet of copperclad PCB material. Traditionally, you'd superglue "lands" of PCB material for connection points. As long as you gave some thought to the layout, and kept the lead lengths short, and understood supply rail filtering and screened sections from each other, you could throw together a rig in an hour or two.

I remember building a really quick 80 Watt rig in a couple of Eddystone diecast boxes, with the exciter and link receiver in one, and the PA in the other. They were thermally isolated from each other by a piece of polystyrene ceiling tile, and held together with four nylon nuts and bolts. The two boxes had nut-fixing feedthrough capacitors for their power connections, and were linked by a piece of coax.

The input from the link receive aerial was a Belling-Lee socket (the usual TV aerial socket), and the RF out was through an "N"-Type. The power supply was lashed together and housed in a plastic Ice-Cream tub! The who;e rig was built and tuned up in about 2 hours, to get a recently raided station back on the air quickly.

Later on, we used PCBs. The first ones were home-etched, using the pre-sensitised UV resist double-sided PCB material we used to get from Farnell. The board layout for the track side was put on to acetate sheets, using crepe tapes or "Letraset" PCB layout rub-down transfers. I had a big UV lightbox for the purpose, and once the layout was on the acetate, it took no time at all to make PCBs by exposing the blank board to the UV, developing the board in photographic developer, and then etching the board in either ferric chloride or sodium persulphate. Drilling all the holes used to be a bit time-consuming, and counter-sinking non-earthed connections was a bit of a pain, but the board quality was superb. I made acetates for Band II exciters and PAs, link receivers, link transmitters, and for some mediumwave gear, too.

Later on, I found a friendly PCB manufacturing company in West London who would turn out really good PCBs at a reasonable price (as long as you didn't want them overnight!). They used my acetates, and duplicated the layouts so that they could get 12 boards out of a single exposure and etch. They would then guillotine the boards and provide a dozen at a time of each board, drilled, tinned, and ready to go.

The PLL I preferred in those days was a simple CMOS affair, using a cheap 4 MHz crystal for the reference. It would work at any frequency up to about 70 MHz, so my rigs usually had a VFO at half-frequency, steered by the PLL. The circuit of the PLL was really simple, just five cheap ICs, a 74HC4060 for the reference oscillator and divider, a 74HC4024 as a divide by 8 "prescaler", a 74HC4040 which was diode-programmed to choose frequency, and a 74HC74 and 74HC00 for the phase comparator (which gave a really reliable "locked / un-locked" output. It could be reduced to 4 ICs if I used the 4046 phase comparator, but its lock detect wasn't entirely reliable. Later on, Philips brought out the 7046, which was an enhanced version which had a reliable lock detector, but they were much more expensive.

I used the same PLL circuit for link transmitters, but had extra stages of frequency multiplication to get it up to Band III. The link receivers usually used cheap 49 MHz radio-control crystals multiplied up to give receive frequencies around 210 MHz.

My exciters usually ran from 12 or 15V (regulated), and the PAs were nominally 28V supply jobs (though I usually used around 31 or 32V), and I used to use a stud-mounted aircraft transistor from Birkett's in Lincoln the venerable 585BLY, driven by a 2N3375. This combination would easily do 90 Watts or more. I bought boxfuls of them, and made literally hundreds of rigs over the years. I experimented with parallelled transistors for more power, and - because they were so cheap - really didn't mind if the experiments resulted in the destruction of a few of the transistors.

Those little rigs ended up all over the world, and there are still quite a few of them in daily use!

[jvok]

I've built a few of the Zozo 1w pll boards over the last few years, fairly easy to build, only one coil to wind and always worked well. I've had one on air for the last couple of months running 1w into a GP antenna in the loft and it hasn't missed a beat. Also built one into a 100w rig with an mrf101 amp for a station I engineered for, they had it on air for a while until the Ofcunts got it

Only issue is the PIC sometimes doesn't boot properly and stops the PLL from locking, easy mod to fix with a diode and a cap which I posted in the thread

viewtopic.php?t=2897

The mod: viewtopic.php?t=2897&start=100#p36425

[radionortheast]

I was just thinking of this last night, you could twist/solder the leads of components together make something that way but you have ics or ic sockets, would make it more difficult, they don’t have long leads doh. I suppose the ground lead of the ic could be maybe pointed down soldered to a copper clad board it could be glued down with the rest of the leads sticking out, giving you something solid to solder against.
Maybe theres some way of drawing/glueing your own tracks, with stripboard, would get confusing you’ve got both the top and underside, if the components were in free space, just thinking of twisting leads/soldering them, or maybe soldered on top of something would be easier to know what was going on, perhaps less chance of error. Often the fact you have a top and bottom makes it hard to diagnose a fault, the more components are there, the harder it is.

Thanks I think I may of seen the zozo, I will look into that, sounds like it works fairly well, I think I may have a go at that one, since it has been recommened. The nrg pll was very good, is quite complicated, the amount of components involved, suppose the way to get it working would be to build the oscillator, check that it is working, before trying to build the rest of it. I don’t think they are generic parts, in the oscillator, having to source the components for it, likely to have source from dogdy companies it could be quite hard, obviously it was much easier with kits all the parts were provided. I think the ic’s are all ones that can be got, from the sound of later versions had a particular ic, were people could get the wrong ic were it wouldn’t go up to the frequency needed? atemps were made to use less ic’s but the ic wouldn’t work in the ic socket had too many legs.
The only problem with the nrg pll is the tunning, tuning can be tricky, best to keep it on the same frequency, using something like a metal tool, you will get a lock but taking the tool away will likely make it unlock so a plastic tool has to be used, I always used to tune away silghtly when doing it, listen for it quieting, then take the tool away it would lock. Trimmers also have a lifespan I suppose, the plastic wearing over time, they can become hard to ajust, sounds like it was too complicated to get rid of the trimmer.

[EFR]

I have done deadbug style protos, just solder ICs upside down, ground pins to copper and remember that they are upside down.

Then rest of the pins are up.

[radionortheast]

yeah I don’t know if the zozo might be too hard, as I see a toko inductor type thing, there is some mention of beable to use an air spaced coil. Also there is a transformer to wound, I don’t know if this just do with the rf amplifier stage or is part of the oscillator, can't find a circuit diagram, also the use of old programmes used to program the chip, the way to program it seems abit vague.

[jvok]

I have a whole box of the metal can tokos used in the zozo if you want some. Also might still have some of the plastic ones used in the matching circuit, would have to check.

The transformer is the input matching for the power stage, wideband matches the power stage to the driver stage. Its really easy to wind, just twist 2 lengths of magnet wire together (I think 18swg but not sure) then wind 4 turns on the core. You can get the T37-17 (blue/yellow) cores from Enigma https://enigma-shop.com/products/t37-17-ferrite-ring

You'll need a pickit3 to program the PIC before you fit it to the board. You can get pickit3 clone pretty cheap on amazon

[radionortheast]

Thanks, I found the components list, I must of downloaded some of the files to do with the zozo a year ago, it has instructions how to wind the transformer. I took one look at the toko, though this is something from an old am/fm radio, didn’t like it, 2t5 toko inductor did confuse me abit i’m glad its availble from engima,pickit3 will be got through amazon, suppose it can be programed like an Arduino.

I saw an interesting video using an arduino to control saa1057, i have arduino seems about the same as wiring those si things. This is the closest to a lay person been able to make a pll, the easiest way, if you could use an uno instead of a pic, I suppose why wouldn't you. What we're interested in is the cleanness of the signal if a little computer can do the grunt work then why not, something that turns on locks on frequency just works is what we want, easier to select the frequency as its written into the script, the computer does the binary, a lock frequency table is not needed.



looks like script there, library, if anyone might want to have a go
https://github.com/junon10/saa1057

maybe someone should put this forward to the makers of the zozo, it would make it easier for someone to make a clean pll, with the si things you can set up a frequency display, though that would make things abit more complex, I imagine it could be done.