Topband: BCS Clone 80m trap problem

[Tom Rauch]

> The inductance of the trap coil is ~11.5 uHy and the Qu
was measured
> at ~255.  The coax caps (total) measure ~220 pf.  The trap
started
> to fail at only 800 watts while testing it on 160m (it was
acting
> as an inductance, not a trap, on 160).  Obviously the RF
> voltage across the trap (inductor) has exceded the voltage
rating of
> the coax!   So I'm not so sure where I can go from here.
Any
> suggestions?


Traps made from coax are by far the worse traps I tested for
Q, loss, and power rating.

http://www.w8ji.com/traps.htm

I'd suggest moving your trap above 75M, not below 80M. When
we put the trap below the band we decrease antenna length,
but we also increase loss and voltage across the trap on the
next band down.

With a trap with distributed components the quality must be
measured by measuring ESR (equivalent series resistance) and
reactance on the pass frequency and EPR (equivalent parallel
resistance) and reactance on or near the stop frequency. I
wager the real Q in your trap is 100 or less.

The power rating of a trap used in a dipole is halved when
used in a Marconi vertical and it becomes even worse in an
Inverted L.

73 Tom