Dear Walt:
As I remember, and this was a long time ago, the 916's unknown port
was less convenient to use than was the case with the 1606. As several
have pointed out, one needs a competent detector.
For VHF/UHF work, GR had an "admittance" bridge that worked very
well. Used one to tune a 400 MHz feed (of an 85 foot dish) so that the
feed was resonant at two frequency bands 60 MHz apart (30 MHz IF strip).
Thanks for the memories.
A correction to what I wrote: I have a CIA-HF from AEA, not a VIA.