Jim Kelley wrote:
Richard Clark wrote:
On Fri, 25 Jul 2008 11:23:55 -0700 (PDT), "
wrote:

We've been having trouble with bicycle thieves in my neighborhood. I'd
like to set up a "bait-bike" that includes a low-power pulse beacon AM
transmitter inside the frame and ***no visible*** antenna outside the
frame. I'd like to have approximately 1-mile range. I've built a
couple of Ramsey kits, but don't have much expertise.
- I'd appreciate any recommendations for a transmitter circuit.
- Will the frame perform as an adequate antenna?

No.

- How about a dipole made from insulated wire taped to the exterior of
the frame?

Equally unlikely.

If you have built Ramsey kits for AM transmitters, you should be well
aware that they rarely transmit more than a block for the suggested,
large (relatively speaking, of course) antenna. Putting something
smaller, inside the frame is like trying to yell through a straw.

Look for an FM transmitter kit. The antenna can be the frame and a
wire wrapped around what looks like one of those kid's fiberglass
whips for a flag. The whip only has to be a meter long at most.

73's
Richard Clark, KB7QHC

Alternatively, Petco has an electric fence kit that could be attached to
the frame. :-)

ac6xg

Put gentian violet powder on the hand grips, then look for purple hands
on the thieves.