zorgrian

modified 3 years ago

The Grenade Pirate Radio Transmitter

326

07:00:31

⭐️⭐️New⭐️⭐️
⭐️ BJT VERSION⭐️

This is ideal as input to the Chinese 45 Watt amplifiers available on eBay. These amps only require mV input. 

This circuit has not been tested with these amps. Nor has it been tested at all. 

published 7 years ago

zorgrian

7 years ago

Please dont use this above 7mhz. Just below is fine for pirate AM

zorgrian

7 years ago

Unless you are a licensed Ham.

Robert_Kidd

7 years ago

MHz?

hurz

7 years ago

No, log(e)(x)=0.434x LOL

stanislav_maslovski

6 years ago

Not bad!

hurz

6 years ago

for my taste a little to much ringing, so it needs some finetune to give more power into the output filter, cuz now you can see after a while the power drops more and more

zorgrian

6 years ago

@hurz, yes you're right. A proper filter would be better. However, this thing is designed to feed into a 45 Watt amplifier. After the amplifier, there should be another filter

zorgrian

6 years ago

Oh.. OK.. So i didn't read your comment properly. So you're saying the filter is cutting energy at desired frequency? Or that there is a mismatch between the output and the filter????

hurz

6 years ago

no no, just watch the output signal a little more then a few secondes. Wait and see how it is going away from your reference shape and getting smaller and smaller. This is problematic for the low power modulated parts of the sinewave. the signal drops jnto a very low constant signal which makes the overall result very nonlinear.

zorgrian

6 years ago

Ok so how do i cure this? This was supposed to be simple lol! Any help much appreciated.

kiani

6 years ago

I think with 200kHz there is a beat frequency, a subtracting one,, which rings for a while.. Try 300KHz,, and check.

kiani

6 years ago

I haven't checked having the T after the pie. Yet.

zorgrian

6 years ago

I built this thing messy style on plane copper clad PCB material. Obviously i didn't inject 200 kHz. Instead i plugged in an mp3 player. After the modulator/ Excitor, i also put a 3dB pad so the tank is operating with a 50ohm load and because, the 45 watt Chinese kit amplifiers really don't need much input to work. For the RF square wave input i use an Si5351 module $3! This is controlled by an attiny 85 (programming done on arduino ide! The result is awesome! However, i am still interested in what is wrong with my simulation.

kiani

6 years ago

Also EC does not like more than one source in board... The sampler gets headaches..

hurz

6 years ago

disable the modulation with 200kHz amplitude down to zero volt and run the simulation. You will see it does start with a carrier of 270mV peak but then over a long time it does drop to 73mV and even below but it takes ver long to see that. The mixer must be lower in resistance, so more current power you get out. Now its quite limited.

hurz

6 years ago

Hey @zorgian, i have tuned a little the mixer. I made it more powerful to not drop the voltage as i observe in your circuit. This version here drops to 460mV after hours of simulation 😂 i changed the coupling cap to be able to go down in frequency close to 20Hz. http://everycircuit.com/circuit/6137454348992512

zorgrian

6 years ago

@hurz, thanks! It looks great now... Hurz the wonderfixer!

zorgrian

6 years ago

I will try this in a messy style build. It has to be better in the real world, yet the sound i get from the old circuit is OK. Maybe your modifications will produce less IMD from the mixer. The idea was to make this mixer with no transformer, which i dont normally do, but i was surprised by the results. Now it should be even better. Thanks again!

kiani

6 years ago

If i had the gear i 'd do it with FET s,,, and reduce switching losses..it would be a jewl Thief modulator no or little power waste..

zorgrian

6 years ago

Its got MOSFETs

zorgrian

6 years ago

Part of @hurz modds are in there, however i missed out the 1 ohm R before the tank. This probably is there to reduce the ringing or, lets say deQ the thing

zorgrian

6 years ago

Please ⭐️note⭐️ it now has the all important ⭐️ factor, without which we are all utterly lost

zorgrian

6 years ago

It does suffer the same problems as the BJT original despite more juice going through. MOSFET version is non good. No gain (pun intended)

hurz

6 years ago

i think you need more in your headline and it will be much more powerful 😂

kiani

6 years ago

The square wave is on 40% on 60% off. Loosing energy maybe there.. Is it intended 40 60 ratio!? Maybe you didn't notice...

zorgrian

6 years ago

I myself, personally, would not use MOSFETs for this circuit. No! Why do i say this??? Because, it is a long tail pair BJT based design. There is nothing to be gained by use of MOSFETs. Not here! Elsewhere yes yes yes! ⭐️

kiani

6 years ago

I am a bjt person too. Fet maybe usefull in VLSI. Even there it is like tailoring playing arround eith w and L.

hurz

6 years ago

MOSFET in this low rf frequency range are useable, but also not my prefered choice. Check this http://everycircuit.com/circuit/5044726286516224

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