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adjustable 1 watt FM transmitter?

Posted: Mon May 24, 2004 11:40 pm
by bob
Hi
I've built a 1 watt (fixed) FM transmitter that I would like to modify for adjustable power output. (I want to LOWER the RF power output, crazy I know!)
This circuit design utilizes two transistors, the second feeding power to the antenna.
I'm guessing, if I limit the supply voltage to the power transistor, it would reduce the output of the transmitter. Can anyone comment?
I don't want to limit the voltage for the entire circuit because of the PLL circuitry.
Thanks for your help!
Bob

Posted: Mon May 31, 2004 1:07 am
by bob
I designed a solution and it seems to be working well.
I added an adjustable voltage regulator just before the ferrite bead and rf choke on the supply for the last power transitor. Running at a fraction of the power runs alot cooler and uses less power. nice!

Hi Bob,

Posted: Sat Jun 05, 2004 1:09 pm
by rich.freeman
Could you send me details of the circuit you are talking about,
I am interested in making a similar circuit to send stereo analogue sound from mp3 player to car radio? if this is possible.

Thanks in advance.

PERSONALLY I WOULD NOT WASTE

Posted: Sat Jun 05, 2004 5:53 pm
by Black_Hawk
YOUR TIME AND EFFORT..YOUR SCHEMATIC IS FULL OF ERRORS

Respects..Norm B