[Antennas] 40_METER_ANT_TRAP

Tue Aug 23 10:04:48 EDT 2005

George K wrote:
>> Has anyone ever grid dipped the KW-40 antenna traps made by the Unadilla Co.?
> Mine dip at 6.1MHZ when on the bench with nothing connected to them.
> They are to be resonate at 7.150 when placed in service but the 6.1MHZ not in service has me confused.
> Can anyone enlighten me?

Maybe this might help. You were probably careful
making the measurement but I would suggest
rechecking the frequency of the dip. Also, if the
traps were laying on a metal desk, that situation
might have shifted the real frequency.
I built my own 40meter traps for an all band
dipole many years ago. I recently had the antenna
down and rechecked the traps. They still dipped
out at 7.2mhz after over 10 years of use. These
are coaxial cable traps that rely on the
inductance and internal capacitance of the coax. 
A trap made from descrete components might have
more of a tendancy to drift with age.
I doubt that the frequency of the traps would
change from being installed versus laying on the
bench.
Regards,
Frank Kamp
K5DKZ