The Ware for January 2021 is shown below.
My call for guest wares was answered, and Don Straney has graciously donated a photoset of various wares that I’ll be pulling from over the coming months.
I thought we’d get warmed up with one of the more vintage, easier-to-guess items from the collection, shown above, and then move to some more challenging items over the coming months!
The switched inductors and adjustable capacitors immediately make me think of an “antenna tuner” (manually adjusted impedance matching network). I don’t know how the board on the right fits in — the relay suggests transmit/receive switching, but I can’t quite think of a function for the rest of it, other than that it _could_ be a receiver, what with all the transistors, adjustable inductors, and a shielded section. Seems like an odd placement, though.
This doesn’t seem to be the entire device — there’s some components out of frame to the left and down, but all of the interconnections are obscured in the bottom right. The capacitor and inductor shafts look like they’re going to shaft couplers, not knobs, so there’s more going on downward. It might be that this tuner is mounted in the same chassis as a transceiver it connects to.
The airy and yet not quite homebrew-looking construction (while being new enough to use PCBs) suggests to me this is some kind of low-production-volume gear.
The inductors are very low power, so I would rule out an antenna tuner. This looks like a VFO with a pretty wide tuning range. The PCB says ‘mixer/IF filter’ to me. But, you’re right on the packaging. This is way too sparse to be a cost reduced high volume device. It really looks like it’s in the box that used to be taken up by tubes in the original version, but time moved on and transistors removed the need for so much space.
The quality of construction rules out amateur radio in my opinion. It’s just way too nice for that. :) I would guess some kind of lab equipment. The construction if that level of quality and commercial radio equipment wouldn’t need that wide of a tuning range.
Funny that you should mention amateur radio, when I saw it it just screamed ARRL Handbook, but from about the 1980s rather than anything current, the hardcover phone-directory-sized volume that you could spend months reading through. If I still had access to any from then I’d be flicking through those looking for something like a preamp covering the HF bands.
The six inductors make me think it is amateur radio gear for the classic HF bands–160, 80, 40, 20, 15, and 10 meters. Well, 160 m is MF, but whatever.
There aren’t any power transistors for producing audio, so it isn’t a complete receiver. It is also a bit too simple for that, comparing it to internal photos of a Yaesu FRG-7. But there is an oscillator, inside a shield. The BNC connector is also a little unusual for amateur radio stuff.
It would be before the WARC bands, roughly 1979 or earlier.
Probably not an external VFO, because that would cover a fixed range in a double conversion superhet. Might be for a single conversion superhet (conversion for a crystal controlled rig?).
It could be a preselector/amplifier. The relay would take it out of the circuit during transmit.
I am thinking it is a 1970’s function generator. The inductors selected by the rotary switch control the frequency range, and the huge variable capacitor selects the frequency. The relay might be for switching between sine and square wave output.
I am going to change my guess from function generator to RF signal generator. It is not a super expensive one like HP. Maybe an EICO or B&K
A good argument in favor of it being an RF generator is the potentiometer on the front panel that is mounted very close to the shaft. You might see something like that used for leveling in a function generator.
Suspect it’s not a an Eico or B&K, they didn’t usually spring for silver-plated tuning capacitors, ceramic wafer switches, and nice epoxy-glass PCBs. I’m thinking somewhere north of Beckman but south of HP.
Maybe a wavemeter. I understand that for many years all UK amateurs were required to have one in their shacks.
The relay on there is made by a company in NYC and it’s not a particularly special part. I wouldn’t think that would find its way into a nice piece of commercial equpment for the UK market. Also, the build quality is *way* too nice for the average ham. :)
The band switch has 3 ranges. Two of the variable cap gangs have 3 inductors each, some with extra fixed caps. The 3rd cap gang has a little inductor in the PCB. It doesn’t seem to be a radio receiver. Maybe its an RF oscillator with a modulator.
Where do you get 3 ranges? There appear to be 6.
It sure looks like some sort of wavemeter — or maybe a noise bridge, but there’s no R element unless it’s the potentiometer we can barely see on the front panel behind the shaft couplers. Weird circuit, with 8 transistors and almost as many diodes. Are the coax cables inputs or outputs?
Some kind of tunable Q multiplier…?
I think I can make out an AB on the rotary part near the bottom, that most likely is an Allen Bradly part which makes it likely to be a pot. Does that help?
Right, that’s the pot I meant. It’s suspiciously close to the bologna slicer, making me think they’re meant to be adjusted together.
They might even be coupled together with gearing on the other side of the panel, but that wouldn’t shed any light on the question other than to rule out a pair of R-jX knobs.
I’ll take that back. It’s 6 ranges. It looks like one end of the inductors is not grounded, so it could be a tunable PI filter. C – L – C, with matched input & output impedances (C are the same).
The mains cable is very dodgy; twisted, siliconed, cable tied ??
There is a shield cage at the top which looks like it has been removed from covering the circuit.
Well, to me this is very unproductive, the transmission and recption of electromagnetic waves are all recorded by Sigint, you can try an old tatic, that is voice distortion on software machine (offline), than transmit, than decode in other offline device, but they scan a a lot of ranges, and detect variations on signals, and have more powerfull machines to test decoding, I would prefer online transmision on EM. So my time, I spend in trying to store photons and how to build an eletrons storage device. If you wanna try confidential communications, your in trouble, they must be personally, second is writing (not postal), third that encryption off-on-off. Leave paranoia, live in nature, to the norsk. Tks!
What do you guys think of a Grid-Dip-Oscillator/a Grid-Dipper? What cought my attention here was really just the six coils. I have seen a lot of these devices with six different coils, mostly replacable. Here you could switch them. And much power would not be needed for the function. It seems a bit too large though, dimension wise. But maybe it is integrated into somethin else, a larger rack maybe.
For a GDO, the coils would need to be externally accessible. Also true for a classical absorption wavemeter.
It could be a tuned amplifier, possibly from a null detector. Its not the GR-1232A, its something much later, perhaps ca. late 1960’s into 1970’s. The chassis finish (slight gold color), inset hex nuts and chunky stainless philips-head screws look familiar. HP? Fluke?