I picked up what turned out to be an unknown valve tester for next to nothing recently. I originally thought it was a Weston 777 Tubechecker but the meter is obviously a replacement and it's not a Weston Tubechecker. The only identification is D^D 965 on the transformer and the underside of the front panel. I understand it's only a very basic emission tester but that suits me fine. I've no idea of it's age but my guess is 1950's.

It did come with a beautifully hand drawn circuit and a note book with a reasonably comprehensive list of valve settings but no instructions. I've spent the past week figuring this thing out and think I've got most of it sorted. I don't just want to be able to use this thing but to understand exactly what it's doing so I'll know how to set it for unknown valve types.

Line compensator with switch E in line position adjusts for mains variations.

Switch A is the heater voltage.

Switch B heater pin. The notes don't always show the lowest numbered heater pin, sometimes giving the higher numbered pin. Not sure if there's a reason for this or not.

Switch C is the element to test. This took a while to figure out, it appears that for diodes the plate is selected and for triodes and pentodes the grid is selected. Why the grid for these two and not the plate?

Switch D is the range, I assume for an unknown valve I'd use a known good valve and increase this to a reference point on the scale for comparison.

Switch E

Pos 1 - Line Adjust
Pos 2 - Shorts. I think to use this setting the heater pin would be selected first and then test the elements one by one using switch C and the test button?
Pos 3 - Test 1. It seems nearly all valves use this position, the only exceptions I can find are 6AQ5 and 6BQ5.
Pos 4 - Test 2. The only valves in the settings using Test 2 are 6AQ5 and 6BQ5 though there's probably others not in the note book. The only difference I can find is that 6AQ5 has two connections to the grid pins 1 and 7 and 6BQ5 has nothing on pin 1. Test 2 seems to isolate pin 1?
Pos 5 - Test 3. I really don't know what this is here for except possibly a heater test.

Switch E appears to be shown in Pos 2 - Shorts if I'm reading the circuit right.

After doing the usual safety checks and fitting an earthed 3 core flex cable, I've tested a few (expendable) valves and it seems to work okay. If anyone's familiar with this sort of tester I'd really appreciate if they could confirm what I've worked out.

Cheers,

Warren

All I know is that the D^D is an Australian Military marking from the 1940's-50's, as it's been found on some Australian insulators used in military applications around 1947/48.

Chris

Hi Chris, I'd wondered whether it might have been a "project piece" for a trainee technician in the Army, hence the markings. It's very well constructed with beautifully laced wiring.

The front panel layout looks like my Paton valve tester and is about the same size and construction too.

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

I reckon this valve tester might be a University Graham. It looks similar to the model TVT, except, yours doesn't have the pin selector levers. The later Paton "Palec" ET4A also had the pin selector levers. So yours may be a simpler version like the earlier Palecs and the Hickok that was discussed here a couple of months ago.

As for testing "exotic" valves, an adaptor socket can easily be made.

University Graham Instuments Pty. Ltd. were situated at 106 Belmore Rd, Riverwood, NSW. They were a competitor with Patons (90-94 Victoria St. Ashfield) for servicemens test equipment.

I have an instruction manual and valve list for the TVT, which also includes a circuit diagram. There may be some similarities with your tester. Unfortunately, this manual hasn't been scanned and at this stage I don't have the means to do so. When I am up and running again, and if you are interested, I can send you a copy.

Meanwhile, I'll trawl through my Radio & Television Hobbies and see if I can find a ad.

Cheers.

I recall that D^D was a shorthand in Oz for Department of Defence. Can't recall exactly but I think it was commonly found on stuff in war surplus shops.

...with the ^ being an arrow similar to the ones on old gaol and lunatic asylum uniforms. This is stamped on the bases of numerous valves I have as spares.

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

Found it!

It is called the "University Supertester". This is a combined valve and circuit tester. Looks like yours has been "chopped" as it is missing the circuit tester part. Sorry, no pictures today. But you can find it on page 57, Radio & Hobbies of September 1946.

Cheers.

I've looked at 100's of photos, websites and manuals over the last week. Those two, the Paton ET3 and the University TVT are the closest I found. Switch E is always the problem, they have a different function. I think I did find a download of the TVT manual, I'll have take another look at it and see if any if the valve settings are similar. I think my switch C is a simple one in all in substitute for the levers.

Cheers,

Warren

^ Just saw your post Monochrome625, thanks for that. I'll see what I can find. Chopped eh? I'm going to have a closer look right now!

Thanks everyone. I found a Supertester on EBay for $600, a few subtle differences but that's without a doubt the one! It makes the $30 I paid for mine seem quite reasonable. I don't mind not having the multimeter section one little bit. Kevin Chant even has the manuals though after a quick look I'm still not so sure about the E switch. I'll download his circuit and compare.

I've just been having a look and if this one's chopped they've done a damn good job of it, I can't pick it. I wonder if they made a compact version.

Cheers,

Warren

I wonder if they made a compact version.

That's what I'm thinking. Perhaps yours ain't the "Super" version.

The E switch is for-

Line: for adjusting the line compensator (centering the meter needle).

Shorts: set for testing inter-element & heater cathode shorts.

Merit 1, 2 & 3: usually set for the type of valve to be tested, when giving a emission test. I'm not sure about the University, but the usual convention for the Palec ET4A is: 1 for diodes & rectifiers, 2 for battery valves and 3 for triodes & pentodes.

As to the question whether or not the tester has been "chopped", I still can't find a valve tester only version, unless a special one was made for the forces.
Is the case of the tester original or does it look like it was home-built? Maybe on the Supertester the front panel comes in 2 sections- one for the valve, the other for the circuit tester. Check carefully around the bottom edge of the front panel.

The other thing I've noticed is that the 2 miniature 7 & 9 pins sockets on your tester are not original. There was originally a "P" base socket where the 7 pin one is and a "Locktal" socket where your 9 pin is.

Cheers.

The case isn't a knocked together job but is different to the one on Ebay. It's got very fine finger joints down each corner with a tiny dowel to lock them in, it looks professionally made. It's longer than shown in the photo with a storage section below the tester panel but the divider between this section and the guts of the tester doesn't look original. The whole box doesn't look quite right to be original to this tester. It's possible the panel's been cut but it's an extraordinary job if it was. I think it's an enamelled panel but no signs of chipping along the bottom edge. It does look ever so slightly different to the other three sides If it's cut, I'm impressed!

As you say, the E switch is usually for Batt, Normal and Rectifier/Diode. I haven't looked closely at the circuits but I think the difference is the voltage they apply for testing.

The E switch on this one is completely different according to the circuit (above) and seems to treat all valves the same except for the pin connections.

Test 1 shorts all the pins together except the test element and the selected heater pin.
.
Test 2 shorts all the pins together except the test element and the selected heater pin and isolates pin 1. From what I can gather there are a few valves around that have an internal connection from pin 1 to another pin such as the 6AQ5. I don't know how many other valves are like this or if there are others with internal connections to pins other than 1. If some do use other pins it's a serious problem because from looking at the circuit it dawned on me that testing one of these valves without isolating the pin would present a dead short to the tester - probably not good for the meter or the valve. It looks like the TST didn't have this setting and having it on this one could be the forerunner of the eventual levers for isolating any pin. Something I'll need to be very careful of in the future. From experimenting I've also discovered for normal valves I can test whatever element is on pin 1 by switching from Test 1 to Test 2 and watching to see if the meter drops.

Test 3 seems to be useless and doesn't connect anything to anything. I suppose you could turn the heater on and off by selecting the other heater pin if you felt the need to do that.

A couple of things stand out that make me question whether it's an original University or something made up using University bits. The circuit is different to other University testers although very similar to the much later TVT. All the wiring as well as the lacing is done in PVC/plastic. It's got those D^D markings on it, it's got an STC 1/24A (half wave rectifier diode?) as well as another 1/12A diode (not shown) although I can't find any info on these diodes or their age. At least that's what I think they are...

All's not lost, with some great help I've discovered usable valve settings and I think I now know how to drive it without doing too much damage.

Cheers,

Warren

The D^D and other indications are a pretty strong clue that this would have been a variant of the commercial version, supplied on contract to a particular specification for the military. There used to be a Department of Supply that issued tenders for such things, and they had a habit of not buying things off the shelf. The sturdy cabinet-work is also probably a special spec.

If you were really keen, you might be able to track down either a tender advertisement or a disposal sales catalogue via the National Library or state libraries. Department of Supply were in Melbourne until at least the mid-60s.

Maven