I have a very nice ham SWR meter that was bought in '74 timeframe in the
electronics district in Tokyo. It is an inline Osker Block unit (never
heard of 'em). I would like to use it, and think I can. But, need an
understanding of how it works first, and this is what I'm seeking help on.

It appears it is designed for 75m-2m ops.

The unit is well built, and is a metal box approx 3" square on the ends, and
8" across the front. It has coax fittings on each end. There is a
75ohm/50ohm selector switch by one of the coax fittings. There are separate
power and SWR panel meters in the box.

There is a calibration chart that is obviously used in conjunction with a
small control device which is knob adjustable. It may be a var cap, or a
variable resistor (pot). The calibration card has two control setting
scenarios: one for 50 ohms, and one for 75 ohms.

The calibration card has different control settings for different power
levels at the same freq.

I ASSUME the cal card setpoints are supposed to give me approx 0 meter
reading if the xmtr signal is seeing close to 1:1 SWR. Is this likely
correct?

And yes, I could easily rig things, using a coax switch, to where I could
take comparative readings between the Osker and my normal SWR meter, and do
a cut and try thing. However, it would be an inconvenience to have to do
this. And, I figure there are people in this group who probably have the
info I'm looking for at hand.