Wolf
On my N7DDC original ATU-10? PCB I measure: With 5W in from my IC-705 and a dummy load on the output side:-
@5W input???? Vf = 1.94v? Vr = 0.005v
So something seems to be wrong with your PCB in the SWR bridge area.? As Onno says, to clarify my previous post, reverse the input and output coax connections and measure again.
In my case I get??? "Vr"? = 0.02 ??? and "Vf" = 1.92v?? (using the same pads as above for Vf and Vr.)? ie the voltages should be close to the same in reverse configuration.
You could also measure the resistance with power OFF.?? With Neg lead of the DVM to ground and positive lead to Vf and Vr I get 47k ohms.? If you look at the Schematic, you will see that Vf and Vr both have a 47k resistor to ground from those points.
If you reverse the DVM leads the resistance will fall as the diodes will become forward biased.
eg in my PCB, reversing the leads gives a resistance of 33.5k ohms.
This should help to isolate the problem with your PCB.
You should? also measure the resistance of your dummy load to verify it is 50 ohms.
Glenn
