Although it sounds like some Star Trek McGuffin, a Q-Meter is a piece of test gear that measures the Q factor of a tuned circuit. [Thomas] got a Boonton meter from 1962 that wasn’t in very good shape, but it was a fun teardown, as you can see in the video below. The meter had signs of a prior modification or repair, but still a nice peek into some vintage gear.
The meter could measure up to 260 MHz (or megacycles in 1962 parlance) and had some unusual features, including an oddly wired AC transformer and a “voltage stabilizer” to ensure a constant AC voltage at the input. We have to admit, we miss the days when our test equipment had gears inside. Then again, we don’t miss the tubes and the high-voltage stuff. Because of the high frequency, the unit even has an oddball acorn tube that you rarely see.
You may notice the meter has a mirror in a strip on the face. This is a common feature of high-precision analog meter movements. The idea is that you move your head until the needle hides its own reflection in the mirror to avoid parallax errors in your reading.
This isn’t the first Q meter we’ve seen; in fact, one was pretty similar but a bit older. While you can get a lot of new gear cheap these days, there’s still something to be said for vintage test equipment.
I love vintage test gear, and used to have a modest collection of it in my shack. I was particularly fond of the old Hewlett-Packard stuff. My favorite piece was my HP 5245L frequency counter that I picked up for $15 at a swap meet. It had a nixie tube display and was accurate to within +/- 1 Hz at 10 MHz, despite its age.
They just don’t make stuff like that anymore (which is both good and bad).
Thanks for the trip down memory lane!
Ah, an “acorn tube” triode 955 – this was one of the first real HF tubes in the 1930s.
I have a Boonton 80, which I restored to function. It also contains an acorn tube, along with a pair of now-unobtainium (but thankfully intact) glass bolometer capsules. The capsules are set up in a bridge arrangement to regulate output gain and thereby maintain calibration… no doubt bleeding-edge tech when this instrument was first conceived.
I found a 1949 price listing for the Boonton 80, $590. Wow. I bounced that against an online calculator that claims that instrument would have cost $7,700 in today’s dollars.
Oh, it also has a feature common among instruments of that era… it’s so heavy that if you chain your mobile home to it, the mobile home will never blow away in a tornado.
Clickbait thumbnail with hyper face expression. No thanks.
You’re missing out then, Thomas makes some really good videos.
“hyper face expression?” It’s just a guy smiling slightly.
Mirror strips were a common feature of measuring instruments, it does not mean high precision. I guess it might have meant that once but if so it was a cheap thing for a manufacturer to add to make their instruments look better than they are.
If they didn’t have a mirror you a priori knew it was junk.