Reg Edwards wrote:
If I remember correctly, the relay was located more than
1/4-wavelength along an end-fed wire on the 160m band.

Thanks Reg, that makes sense now. That's quite different
from breaking a 1/2WL loop in the middle using a relay.
The voltages at each end of 1/2WL are 180 degrees out of
phase so the relay has to handle double the voltage existing
at the ends of the wires. A quick estimate of the voltages
at the ends of a 1/2WL dipole being driven by 100 watts is
1000 volts RMS. The relay would have to stand off almost
3kV PTP.
--
73, Cecil http://www.qsl.net/w5dxp