[Hammarlund] electric fence noise

[Patrick A. Thompson Sr.]

I've had a nearby electric fence to contend with for many years.

When receiving with my IC-746 (modern solid-state) the POP is annoying but
the noise blanker helps and strong signals are never a problem. A IC-706 is
the same and a Drake TR-4 is okay as is a SW-350.

I'm connecting to the same 75 meter loop antenna with each receiver usually
through a T-match tuner.

With my HQ-180 or HQ-170 the POP is very strong with the S-meter nearly
pegging and the AGC recovery way too slow on anything but fast AGC.
However, the audio when the fence is off is outstanding and the AGC seems to
function as intended.

What this means is that when the fence is on the HQ-180/HQ-170 are unusable
but other radios don't have a problem.

What's going on here? Why is the fence discharge only an annoyance on some
radios and a major problem on others?

Any clues?

Pat
wa4tuk