STL TX AND RX 330MHZ

[radium98]

Hi
here i post what i have ,an stl transmitter 50mw for band 330mhz , and it is receiver rx that use ca3089 demodulator ,i ask if you could publish a layout for an receiver like this
thanks

[sinus trouble]

I find it highly unlikely that anyone here is going to design them for you!

We can offer some advice though!

As it is important to keep connections short, try to design/orientate with components connected directly together!
Ground connection positions wont be so critical as your PCB will have a large ground plane area!

Try to separate your PLL and RF into two separate sections as jumbling them up together will cause problems!

Also I find free PCB design software can be useful for laying out a project! Far easier than on paper as you can adjust and tweak your design with little effort

Good luck

[Albert H]

We'll happily design the PCBs for you. Our design rate is £1500 / hour, payable in advance. I estimate that a viable, tested layout will probably take three working days at 8 hours per day. That's £36k, please. If we're allowed to retain the Copyright on the PCB designs, we'll discount to £30k.

Properly designing PCBs - particularly RF PCBs - isn't a trivial undertaking. We design with multi-layer boards these days, and have to account for track to ground and track to track capacitive and inductive effects. At UHF, every piece of track, every wire, every component lead and every component itself exhibit some kind of non-obvious RF effect. Things are made slightly easier by the use of lead-less, surface-mounted components, and by their lowered profiles, but it's still not simple.

We've just designed a UHF Radio-Microphone system for a well-known musical equipment manufacturer. The project took three of us over two weeks - full time - to complete. The circuits of the transmitter and receiver were simpler than the ones you've presented above, except that the receiver used diversity reception techniques to eliminate nodal cancellation problems. There are two versions - one with a vocal microphone input (designed to plug on to an SM58 or similar), and one with a guitar-level input. Both are equipped with companding noise reduction and adaptive receive gain, and the practical range of the units is around 400m in free space. The equipment manufacturer was happy to pay £180k for the designs, PCBs and prototypes, since they'll sell a lot of these at £250 - £280 per pair.

Radio pirates really don't seem to appreciate the knowledge that the real engineers have gained. They buy their gear from people who just copy from people like me - we're the ones who actually did the educational time and industrial training - and they complain when OFCOM claim that they're causing interference!

[radium98]

Strange who said that i need a pcb layout ,i have this and i want to share with the forum people.i have done it for tx side .

[sinus trouble]

My apologies for the misunderstanding Mr Radium

Nice work! Very neat!

[teckniqs]

That's your thirty six grand saved.

[Albert H]

My apologies for the misunderstanding Mr Radium

Nice work! Very neat!

It looks pretty, but it's unlikely to work very well at >300MHz. There's no groundplane, so stability will be poor. There are no screens between the functional areas of the circuit board. The digits are certain to get into the modulation, and the PLL won't be stable with RF around the low frequency parts of the circuit.

A worthy attempt, but unlikely to work properly.

[sinus trouble]

That's your thirty six grand saved.

[Albert H]

Sinus - you can laugh all you want, but pretty PCBs often don't make for working gear!

Actually laying out a PCB for RF is tricky - it took me a long time to learn how to do it properly, and that's why I can charge (and get) £1500 / hour for design work. I have five days in Japan next week, finishing the design of a receiver for a well-known manufacturer. (It's nice to fly First Class on JAL). It's a very long way from building throwaway rigs to "lose" up tower blocks!

There's not many real engineers left in this corner of Europe. I've left England now (mostly) and live in the Netherlands, Spain and Croatia for most of the year. All the really good engineers (like me and the guys I trained with) got jobs in the USA or the Far East - for very much more money than they could get in Europe - which is why I spent almost 10 years in the USA and Canada and have been able to (almost) retire early.

It's funny to introduce an unusual component into a rig design, and then watch all the copiers scrabble around, trying to get the "right" parts. For example, back in the late 80s, I got a box of 2N2222C transistors, branded "ST". I had a thousand of these, and used them widely in Band II exciters, since they had lots of gain at 100 MHz, and could deliver almost 250mW. They were great, and I'd bought them from a surplus component supplier for 0.05p each!

A pair of the 2222s would drive a 2SC1971 to around 8 Watts - a useful amount of drive for the bipolar output devices I used in those days. I also got a lot of MRF317s very cheaply. If you ran these at 80 - 90 Watts, they were practically indestructible.

Every copier around the South-East of England tried to get hold of these same components. I even had the layouts copied and my PCBs reproduced. I started to obfuscate my layouts by using three or four layer PCBs and lots of surface-mounted components. There was even one run of PLL exciters that were sealed with epoxy resin!

Ridiculous!

[sinus trouble]

Sorry Mr Albert, no offence intended!

To me, Your knowledge is priceless and you have no gain but to educate others by sharing it!

Sometimes we take it for granted especially when criticism is involved!

I guess we learn more from 'F*ckin up' than praise!

[Albert H]

Just as an example - take a look at the "300W rig" offered in the "For sale" section:

It's actually just the power amplifier -"needs a new exciter". The use of the S18 moulded inductors shows that the constructor (and the original designer) of this board didn't know what they were doing - I've seen the cores fire themselves like bullets out of those coils when they got hot! The output filter isn't going to do much either - the coils should not be able to couple to each other longitudinally - and the filter (if correctly constructed) should be screened from the rest of the PA. Inter-stage screening is also a sensible precaution, but this solder-jockey didn't know that. The harmonic output from that thing will be horrible. Those are just the obvious faults visible at a quick glance!

This kind of inept stupidity got pirate radio a bad name.

Back in the 70s and 80s, we made sure that our rigs were truly clean, and took every precaution to avoid interference. The technology was only known to a few of us, and rigs were relatively expensive. We shopped around for components, and in the days before the interweb, we had huge catalogues from all our suppliers. Some installed rigs lasted for a couple of years (in weekend-only use), because they didn't cause any interference.

[nrgkits.nz]

The only coils that are designed to couple to each other are the ones wound by Paul Hollings

[Albert H]

[radium98]

@albert what i can use as transistor in oscillator a mpsh10 -ksp10 or a c3355 ? or what else if i could find

[nrgkits.nz]

@albert what i can use as transistor in oscillator a mpsh10 -ksp10 or a c3355 ? or what else if i could find

BF981 is what I use

[radium98]

Hi ,thanks for reply but bf981 is not like c3355 in case ,a replacement to me for bf981 in rdw was a tf121.but here i can not replace it different size

[yellowbeard]

Hi ,thanks for reply but bf981 is not like c3355 in case ,a replacement to me for bf981 in rdw was a tf121.but here i can not replace it different size

They have the MPSH10 at enigma shop
https://www.enigma-shop.com/index.php?o ... ow&cid=890

[radium98]

I am so far to guet them.

[radium98]

Is it better to put mpsh10 as driver and the final c3355 or the reverse

[radium98]

Is it better to put mpsh10 as driver and the final c3355 or the reverse