Radio Transmitters-Power

[Domayele]

Is There Any Electronic(s) Engineer(s) Here?

Through years of hardwork & trials I have successfully designed/Invented the Radio Transmitter circuit shown below.

BUt this transmitter can cover a range of 100-150meters(with an antenna of hight 3-5meters) only, and a frequency range of 90-103MHz(by adjusting the rheostat or the number / size of the copper wire inductor).

I therefore need help on how to Increase the Power of this Transmitter by at least 10 times such that it can cover >1Km(1000meters).

Thank you.

DiAGRAM TO BE ATTACHED:Usage (Not linked)

[YT2095]

Hmmm.. alot of the parts you`re using in there are redundant! and some actualy work against you

 

r1 r2 r3 c1 c2 are just filters /impedance matchers at best!

VR1 only changes freq by a damping effect (bad electronics!) scrap vr1 and make C4 a variable capacitor. and c3 shoud go across R4

 

C6 is totaly not required, take it hard to ground, it`s best way, the antenna cap you`ll need but go 0.01mfd max.

 

 

what tranny are ya using? I like 2n2222, but BC108`s are good if your pushed for parts.

[qazibasit]

I am getting the whole circuit but i am confused of how to make an antenna (of what material) and instead of the rheostat can i use a tuning capacitor. And what about the L1 the coil what type of coil i have to use with how many turns.

[YT2095]

I am getting the whole circuit but i am confused of how to make an antenna (of what material) and instead of the rheostat can i use a tuning capacitor. And what about the L1 the coil what type of coil i have to use with how many turns.

plain copper wire, cut to the correct SWR length will do just fine

 

yes, using a variable cap would be significantly better than a resistor, as outlined in my last post.

 

as for turnings, that all depends on wire gauge, diameter, material, and rellated capacitance, 5 to 7 turnings of enameled solid core copper wire will bo roughly correct on a .5cm dia former for the 90 to 103 Mhz range, this can of course be adjusted by the vari-cap or spacing out or compressing the coil windings

 

[edit] it`s also a good idea to use a Zenner regulator onboard too, as voltage fluctuation will effect frequency

[Domayele]

Thank you YT2095 !

I did just as you instructed in your first reply and the quality of the sound of the circuit has improved drastically as well as the easiness of tuning.

However the power has only improved just a little over 10meters :making the transmitters maximum distance of coverage 160m approximately.

Any help again ?.

Its Clement saying hi from Ghana.

[YT2095]

what transistor are you using? I reccomend a 2N2222 or a BC108 (if you`re really stuck). the 2N2222`s my personal fave, and I`ve acheived just over 1km (1000 meters) using one

 

one of the things you`ll have to do, is calculate the correct antenna length for the frequency you`re using, you may accomplish this by dividing 300 by your frequency, that will give you your wavelength, then divide that number by 4 (for a quarter wave antenna) then times it by 100 to give you the antenna length you meed in centimeters, then get a peice of wire and cut it to that length, that will not only improve your range, but also reduce feedback to your RF transistor, thus reducing heat

 

[edit] if you get this calc correct, your answer for the frequencies you`re using should be about 75cms for a 1/4 wave antenna