Radio circuit diagram implementable?
Hey guys, I got permission from my school/state to build an FM radio using the 27MHZ frequency and a maximum of 4 watts.
I want to choose simpler circuit diagrams first and then move on to more complex ones.
I found the following two circuit diagrams:
Since the transmitter was originally designed for 90MHz.
My question now is whether I can simply reduce the resonant circuit to 27MHz and then determine the operating point of the transistor and the values of the resistors and capacitors experimentally or whether I should urgently look for another circuit diagram.
(2 votes)
Loading...
There are a few things to say (the first scheme is the recipient, not a transmitter):
Building such yourself is interesting, educational and tempting. But it’s very difficult to have a clean transmitter at the end.
So I would recommend you join a local amateur radio team to get there. Or google still according to further schemes with
27Mhz transmitter.
Good circuits are complicated and expensive in tuning.
Update: I have found a person with sparkling that can help me and of course knows which frequency ranges are allowed and hopefully also how to filter the harmonics
Hard to say… I would first change the oscillating circuit in the upper circuit, increase the 33pF, first leave the coil in such a way, possibly also oscillate.
The frequency swing is likely to decrease as if you can change that, at least I can’t just say that.
It may therefore be more sensible to leave the 33pF capacitor to increase only the coil inductance.
An Oszi would be very helpful here.
Do you think I should buy a 27MHZ quartz?
In addition, there’s hardly anything else with FM.
Simply replace the capacitor with a quartz will not work.
Then I don’t understand your comment with the Oszi. Did you mean an oscilloscope?