I have recently run into something I found rather interesting.
I have a Hustler 4BTV (it was a 5BTV but somewhere in one of my
many moves I seem to have misplaced my 75M resonator :-).
I have always thought it was nice and was happy with the performance.

Then I was out of ham radio for a couple decades. Got interested again
and set up some stuff. One is the 4BTV and the other is a home brew
single band 20M vertical. Didn't do much but listen while working in
the basement until one day I happened upon a decent condition RCA
AR-88-F receiver. Fired it up and it worked really nice. Had it
hooked up to the 20M vertical and was hearing a lot of stuff (including
WWVH which I have never heard before!!) So, I decided to try the 4BTV
and other bands. While still in the area of 15Mhz I switched antennas.
Nothing. Dead silence. Back to the home brew. Wall to wall stations.
Checked the feed line. OK. Hooked up the antenna analyzer. Low SWR
points exactly where I had set them when I set it up. But, on any band
at any frequency the 4BTV is closer to a dummy load than an antenna.
So, the question... Are these trapped verticals really that bad? Is
it possible that ages has made this happen even though changing the
length between traps does change the resonant frequency of the antenna?

At this point I am considering just home brewing some more single bane
verticals for the upper bands. Maybe even 40M although that would be
more difficult. And, looks like I will have to try and revive my HQ-1.
Not a lot of promise there as the wind here where I live is very
destructive.

BUt, I would really like to know why the 4BTV is so bad. It would be
truly disappointing to find out that for all these years it has been
this bad and I just didn't notice as I had nothing to compare it to.

bill
KB3YV