Help identify old instrument. - Page 1
Forum section: electronics / beginners

author: jorgeh
author_rank: Regular Contributor
timestamp: July 08, 2022, 10:16:18 pm
content: Hi.I have this device that im not finding any information about. it looks like some kind of powersupply but then again it has several sockets for old glastubes.any idea from the pictures what it could be.on the front says the left know Netzangleich it would be something like power line matching compensator.Ausgangspannung is Output Voltage.any hint will be apreciated.

author: nightfire
author_rank: Frequent Contributor
timestamp: July 08, 2022, 10:42:13 pm
content: FRom the looks of it, I would assume that is some kind of old tube Power supply for high voltages.At the lower left side, the input cables are cut off, power switch is broken, but there are some lights for operation.The handles would suggest Rackmount use, which would indicate industrial or military use.Mounts are probably for tubes, as they were prevalent before the age of transistors, also in one picture one sign is "Heizung"=Heating.The left dial is probably used to adjust the stuff to the (not very stable) mains voltage, like some transformers used in east germany to keep the voltage for the TV stable...http://www.jogis-roehrenbude.de/Roehren-Geschichtliches/Roehren-Netzteile/Roe-Netzteile.htmgives some background about those Power Supplies.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: July 08, 2022, 11:59:05 pm
content: I don't know but:The big red inductor and the stacked high volt ceramic capacitors look like a RF power amp. Tube RF amps commonly have a Pi network with a big inductor and variable capsThe variable caps are not here but the switch does switch in "variable capacitance"The knob on the right looks like a band switch. Connected to the stack of HV caps. But is says Output Voltage Right???Possibly a low frequency AM Amplifier? up to 1060 Hz??The big 4 pin socket would be for a rectifier tube probably a dual diode, the other valves would be amplifiers in parallel, could be pentodes.But the "output" connector does not seem to be anything I have seen. It does have a central pin.Perhaps look and see what the central pin and the other 6 pins are connected to, if it is RF Out then perhaps the 6 outer pins are Ground???Perhaps someone will know what kind of connector it is.

author: mclute0
author_rank: Regular Contributor
timestamp: July 09, 2022, 07:40:47 am
content: I would guess an early ECT machine, very low mA at high voltage....

author: gbaddeley
author_rank: Regular Contributor
timestamp: July 09, 2022, 09:26:15 am
content: Looks like a HV DC power supply. Selectable set of regulated output voltages.Transformer primary mains tap selection switch on left. eg. 210, 215, 220, 225 volts etc to allow for local mains variations and fine tune the output voltage.4 pin rectifier tube is missing. Probably half wave.A stack of 7 pin voltage reference tubes are missing. No heater, gas discharge types.Fairly low max output current. 15 mA, going by the meter scale.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: July 09, 2022, 10:29:39 am
content: Rectifier is probably a type 80 tube See this for schematic:https://www.radiomuseum.org/tubes/tube_80.htmlProbably center tap full wave rectification.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: July 09, 2022, 10:54:07 am
content: Does "Netz" mean "Grid" in this case?

author: nightfire
author_rank: Frequent Contributor
timestamp: July 09, 2022, 12:29:40 pm
content: Quote from: Wallace Gasiewicz on July 09, 2022, 10:54:07 amYes, mains input.

author: gbaddeley
author_rank: Regular Contributor
timestamp: July 09, 2022, 12:39:47 pm
content: Quote from: Wallace Gasiewicz on July 09, 2022, 10:29:39 amI don’t think an 80 would handle 1060 V output. At such a low current, I don’t think a centre tapped secondary would be justified. It would be useful to see the schematic of this thing. @OP, feel like tracing it out?

author: jorgeh
author_rank: Regular Contributor
timestamp: July 09, 2022, 02:34:48 pm
content: Hi thanx for so many responses. It was among other HV power supplies. but it got me confused so many sockets. I have some Power supplies with tubes but they have only one. no this many.unfortunately it came without the tubes this one.sure I have it at work I will take more pictures.

author: TimFox
author_rank: Super Contributor
timestamp: July 09, 2022, 03:29:32 pm
content: Quote from: Wallace Gasiewicz on July 09, 2022, 10:29:39 amThe same 4-pin socket for an 80 vacuum dual rectifier is also used for higher-current devices:5Z3 (similar to 5U4 octal) and 83-V (vacuum rectifiers)83 (Hg-vapor rectifier)866 (Hg-vapor single-diode rectifier)Is there any indication on the chassis for what tubes plug into the large number of 9-pin sockets?

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: July 09, 2022, 05:46:29 pm
content: Those are7 pin sockets and consistent with the reference tubesgbaddeleyposted.https://www.radiomuseum.org/tubes/tube_85a2.htmlJust one example.Perhaps the big inductor and the stack of caps is for counteracting any possible oscillations???

author: jorgeh
author_rank: Regular Contributor
timestamp: July 09, 2022, 06:42:11 pm
content: it kinda goes with the other devices i got. it looks like a bunch of equipment for a physics lab. among there are some HV DC PSUs. also old, but not that old.

author: jorgeh
author_rank: Regular Contributor
timestamp: July 09, 2022, 06:45:19 pm
content: this PSU aswell.

author: TimFox
author_rank: Super Contributor
timestamp: July 09, 2022, 10:55:14 pm
content: Quote from: Wallace Gasiewicz on July 09, 2022, 05:46:29 pmNote that the 85A2 and similar gas tubes are not used for "voltage regulation", as in the OC3 and OA2 types (which are characterized over a reasonable range of current, such as 5 to 30 mA), but are used as "voltage references" at a fixed value of current (similar to the use of temperature-compensated Zeners such as the 1N829 series).

author: gbaddeley
author_rank: Regular Contributor
timestamp: July 10, 2022, 04:00:27 am
content: Yes, it looks like shunt regulation, rather than series, otherwise there would be a HV series pass tube and driver / error amp tube.Caps and inductor will be CLC ripple filtering.Good to see some tube knowledge coming out, though in Oz we call them Valves. 😬

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: July 10, 2022, 01:59:25 pm
content: Do you think the LC circuits are there just for filtering?? Was that common? That was one of my thoughts.Are the LC circuits there to prevent oscillations?Or is it possible the LC circuits there to make an AC output as in a relaxation oscillator???Old time relaxation oscillators used things like neon tubes.

author: TimFox
author_rank: Super Contributor
timestamp: July 10, 2022, 04:24:08 pm
content: Quote from: gbaddeley on July 10, 2022, 04:00:27 amAssuming the 7-pin sockets are for "VR tubes", the more likely series is the "0x2" series (zero, not oh).0A2 = 150 V @ 5-30 mA0B2 = 105 V0C2 = 75 VNote that one can wire a group of 0A2s in series for a higher voltage, but you may need to add appropriate resistors to ensure that they all "fire".To start an 0A2 requires an initial voltage of 185 V to fire, at which point it may pull up to 75 mA until the external current limiting allows it into its operating range of 150 V at less than 30 mA.Over the operating current range (5 to 30 mA), the voltage across an 0A2 should vary by less than 6 V. The voltage is also somewhat sensitive to ambient light.The 7-pin series has redundant cathode and anode terminals (to interlock against a missing tube which would apply too much voltage to the load).The similar octal "0x3" series (e.g., 0D3 = 150 V at 5-40 mA) contains an isolated jumper wire between two pins, which is a more straightforward interlock connection.If you exceed the rated 0.1 uF parallel capacitance, these devices may well form a relaxation oscillator.The RCA data sheet has an interesting typo, where that capacitance is given as 0.1 uuF, which would be difficult to maintain.https://frank.pocnet.net/sheets/049/0/0A2.pdf

author: gbaddeley
author_rank: Regular Contributor
timestamp: July 11, 2022, 10:55:17 am
content: It’s unusual that a RCA data sheet would have a typo. Bottom of page 2 gives the correct limit, 0.1 uF. Are there Euro equivalents? This PS is a dead duck without the correct tubes.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: July 11, 2022, 11:26:12 am
content: The RCA sheet does list two different values. .1 uF and .1 uuF.A .1pF (.1uuF) value would be easy to create with just the wiring on these tube sockets.They would oscillate in almost any application.Here are some "Equivalent" tubeshttps://www.radiomuseum.org/tubes/tube_0a2.html

author: TimFox
author_rank: Super Contributor
timestamp: July 11, 2022, 02:00:38 pm
content: I have measured normal tube sockets and they are always > 0.5 pF pin-to-pin.I have seen low-frequency (< 10 Hz) relaxation oscillations with > 0.1 uF across the VR tube, but they are stable with < 0.1 uF.

author: jorgeh
author_rank: Regular Contributor
timestamp: July 13, 2022, 04:23:18 pm
content: Hi sorry for the long delay.here is a picture of the bottom.sorry that I didnt draw it, but there wasnt any paths to be copied.but my question was already answered it was a valve PSU.

author: TimFox
author_rank: Super Contributor
timestamp: July 13, 2022, 04:31:54 pm
content: The alleged VR tubes (7-pin sockets) seem to be connected in series, with 1 megohm equalizing resistors across each, and several lower-voltage taps brought out separately.

author: jorgeh
author_rank: Regular Contributor
timestamp: July 14, 2022, 08:13:16 am
content: May I ask, what would be a fair price for it? I mean to sell it.Im asking as a reference. this one im gonna give it away 4 free. but for future vintage equipment that lands on my lap I would like to know for an incomplete device, what would be the percentage to ask? compared to a broken or working version?

author: gbaddeley
author_rank: Regular Contributor
timestamp: July 14, 2022, 01:07:12 pm
content: It’s difficult to give prices. Gear is only worth what someone interested is willing to pay for it. A collector would want something 99% complete or in working order or easy to fix, and very clean looking and of historic value. Even for parts, the PS is worth very little.