22 PL-259s
Antenna --> lightning arrestor, 4
Lightning arrestor --> coax switch #1, 2
Coax switch #1 --> upstairs HF radio, 2
Coax switch #1 --> antenna tuner, 2
Antenna tuner --> 1 kW dummy load, 2
Antenna tuner --> null bridge, 2
Null bridge --> 100 Watt dummy load, 2
Null bridge --> coax switch #2, 2
Coax switch #2 -- downstairs 100 Watt HF radio, 2
Coax switch #2 --> downstairs QRP HF radio, 2
The null bridge dumps the output of the two downstairs radios into to the 100 Watt dummy load and looks at the impedance presented by the antenna tuner. The tuner is adjusted until the bridge indicates a null (50 Ohms). During tuner adjustment, ~ 1/8 Watt goes to the antenna if the radio is putting out 100 Watts. I've had a few stations come back to me while I was tuning. IIRC, one or more were on the West Coast. Not bad for ~125 milliwatts. There's enough leakage through the null bridge to copy strong stations.
I built the null bridge back when radios did not have internal tuners or SWR indicators. It protected the finals from high SWR, and allowed tune up without creating (much) QRM. It is left in because I do some homebrewing, and it makes presenting 50 Ohms to the HB sets easy.