Archimedes wrote:
When I increase the antenna length to say 30cms, from the recommeded
6inchs or 15cms, the circuit does not work.
The device is a super-regenerative receiver. The antenna
is part of the oscillator circuit. If you change the
length of the antenna, you change the resonant frequency
and/or possibly cause the oscillator to stop oscillating.
Either of those results will cause the receiver not to
work right.
--
73, Cecil
http://www.w5dxp.com