[TowerTalk] Fan dipole Re: Looking for a HP 80/40 Duplexer

[Jim Brown]

On 11/18/2025 12:53 PM, Jack Brindle via TowerTalk wrote:
> To add to the info, assuming your 40 dB is correct, that would put a bit over 100 mW (62dBm - 40 dB = 22 dBm) into the receiver. The rx damage point is about 16.7 dBm. I would definitely not trust that setup, and even if there is no damage, the rx would be completely blocked, precluding SO2R. Filters and diplexer are needed...

Yes, but -- there are many ways to skin that cat. Like RX bandpass 
filters. Look at what W6GJB and I managed in his contesting trailer. 
k9yc.com/7QP.pdf

There are multiple components in the system that allow us to run two 
K3/KPA500 stations on harmonically related bands with feedpoints within 
a foot of each other. Leave out any one of them and it doesn't work. The 
components are double stubs on the 80M and 40M antennas to kill 
amplifier harmonics, serious chokes at the feedpoints of each antenna, 
and W3NQN RX bandpass filters.

73, Jim K9YC