[TenTec] PT-340 noise bridge vs. SWR meter

[Dr. Gerald N. Johnson, P.E.]

I believe the article you refer to was published in the July 1977 issue
of ham radio magazine. It used a four wire toroid winding to balance up
stray capacitances and did worry a great deal about lead lengths. I
built one, made it calibrate to precision terminators and used it for a
long time until basement moisture wrecked the pot (and it was an Ohmite
type AB or Allen-Bradley pot).

I have a heathkit noise bridge also, that seems to do nearly as well. I
find that when I adjust the tuner with one of these that is working
properly, that the rig puts out full power and my other bridges (which
on my main tuner is a reject Collins wattmeter, didn't have enough
directivity to suit the designers so the design that made it to
production was different) show a FLAT load. When I'm lazy, I just hook a
TS-130 to the tuner and adjust for maximum power output while there's a
brick on the key. Actually its generally faster to tune with the noise
bridge. I should build a box to switch the noise bridge into the circuit
so I use it more often, sort of a tuner tuner adapter.

73, Jerry, K0CQ

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