[HQRP] Cables to SWR Meters - caveats !

[K5BDZ@aol.com]

About 10 years ago I did a lot of experimenting with SWR meter RF Sensor  
pick-up circuits.  My favorite of all is the Stockton bridge using two toroids 
(Dave, you're brilliant!)

Regardless of the RF Pickup Sensor design, whether it be single toroid Bruene 
circuit, two toroid Stockton bridge, or other experienment, the below 
problems and solutions were always the same, and the solution given below worked 100% 
of the time to cure the problems noted.

A BIG PROBLEM with inability to null, instability, forward / reverse other 
than 180 degrees diff, etc. and this PROBLEM was always found when connecting 
the RF pick-up Sensor  to the coax and NOT using nearby coax ground but instead 
by utilizing the chassis ground as the RF return between the in / out 
connectors and the RF Sensor bridge circuit.

Therefore I ALWAYS designed the PC boards (or even the perf board layout) to 
include a ground connection running parallel to the "hot coax center conductor 
line" between the connectors and running through the RF Sensor pickup 
circuits.  My GROUND circuit on the RF board was from the XMTR connector , to the 
board, and connected next to and parallel to the XMTR IN "hot circuit" and Out 
the ANT circuit to the antenna connector.

Good luck all... RF Sensor circuits are great, simple, fun, and great money 
savers.  I've picked up some beautiful and sensitive meter systems in nice 
enclosures with bad RF sensors for cheeeep and made various DIFFERENT sensors to 
cover HF, VHF, QRPp, QRP, QRO, and other circuits... all switchable and using 
the same meters.  Oh yes..........mine all track with my Bird if that's any 
interest...
Bill K5BDZ


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