pucho812

Re: Simple Tube Tester?
« Reply #20 on: February 13, 2018, 12:28:40 PM »
if you choose to buy a used tube tester then make sure it comes with the book for the tester. my two tube testers would be useless without their respective book telling me what settings  get adjusted for which tube and which socket to use. 
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.


bibi

Re: Simple Tube Tester?
« Reply #21 on: February 14, 2018, 03:36:23 AM »
I've been considering this one on Ebay--  there are also English instructions that are clearly written if you ask for them.  I like the fact that I don't need to hook up a computer although I do believe there is a tracer function add on for those that need one. 

https://www.ebay.de/itm/VACUUM-TUBE-TESTER-FULL-KIT-WITH-LCD-DISPLAY-KIT-LAMPEMETRE-DIGITAL-COMPLET/262023069804?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

Any thoughts? 

rackmonkey

Re: Simple Tube Tester?
« Reply #22 on: February 14, 2018, 12:31:05 PM »
I've looked at this before. Looks interesting. But MattC said in an earlier post said he asked the vendor/maker of the Utracer (a seemingly similar device) about fault testing, and the guy said that it's not suitable for that. No capability to look for shorts, gas, etc. Just a tool for measuring cathode strength and gM/tracing. I used Google Translate to get the description of this one in the eBay listing, and it looks like it's probably in the same  boat.

But if that's what you're looking for (matching tubes, testing known good tubes) then it may be just the ticket.

Google translation:

Complete kit of high performance digital tube tester, wired, set, ready to use.

This kit consists of a main board shown in picture 2 and a set
peripheral elements pre - wired with the power sources shown in photo 3.

Features and performance are vastly superior to the overall
traditional tube testers and measure a very wide range of tubes.

The first picture shows the assembled unit, picture 3 shows the set of connectors
with pre-wired control elements + power supplies.

Full documentation on request by giving me a valid e-mail address.

Summary of features:

Module dimensions: 146 mm x 133 mm maximum height 28mm + backlit LCD display
25 x 70 mm.

Single power supply: 110/230 V or 12V battery via a converter
optional.

Power Consumption: 25W (35W max.) On mains and about 2A on 12V battery

Voltage, Plate: adjustable from 0 to 450 V

Screen voltage: adjustable from 15 V to 350 V

Grid voltage 1: 0 to - 100 V (by potentiometer 10 turns)

Current range: 0 to 300 mA in 2 automatic sub-ranges: 0 to 34.0 mA
(0.1mA resolution) then 34 to 300mA (1mA resolution)

Short circuit protection: total
(NOTE: this is not the same as short identification. BT)

Overall accuracy: +/- 5% +/- 1 digit

Note: These values ​​are real, the use of a microprocessor allows an ultra-fast measurement mode
which minimizes the power required. Few traditional tube testers are
capable of such measures because they require heavy and bulky power supplies -
the famous Metrix 310, for example, is limited to 100 mA of current plate.

The operation of the device is very simple: it is sufficient to adjust, via 3
potentiometers, anode voltage, screen voltage (for tetrodes, penthodes, etc ...)
and the bias voltage gates to the desired values ​​and, simultaneously, the corresponding plate current is displayed on the LCD screen.

The measurements are carried out at the rate of 2 per second, which enables continuous reading.
parameters and results.
Whether you think you can or you think you can't, you're probably right.

Re: Simple Tube Tester?
« Reply #23 on: February 14, 2018, 03:31:07 PM »
Brimar Bob was making one for commercial release don't know if it's done yet?

http://brimaruk.com/valve-testers/

jim-analog

Re: Simple Tube Tester?
« Reply #24 on: October 07, 2018, 07:13:24 PM »


 Greetings,

 Just noticed this thread. We've been using this tester for over 10 years:

 http://www.tubesontheweb.com/

 It's based on a US Military type Hicock Cardmatic, but uses a special interface box to connect to virtually any primitive DOS PC and no longer requires use of the card set.  It is VERY configurable via software (multiple types/versions of tests, for example triode or pentode connection of EF86, can be set up for a given tube and easily included into the standard menu) and hardware connections. There is an insert point to measure actual plate current with an external meter when other tests are running.

 When we bought ours, there wasn't nearly the options available currently.  However the only tester that seems to include all the features of this AND the graph ability is the more expensive Amplitrex unit.


 The main drawback is that do perform any multi point graphs, the data shown on the analog meter must  be manually entered back into the computer (there is no A:D chain). Otherwise, it's been a very good unit. The OS has been continually updated by the builder and he's been very responsive to inquiries regarding any problems or to help configure special tests. Virtually all socket types are either included or available (from the early 4 pin triode types to nuvistors,  compactrons and loctal.  This unit replaced a Hickok 539C that we'd been using for quite a long time prior that really needed a complete rebuild/rehab.

 BTW for more limited, but in depth testing,  we also have a customized version of the VTV (Eric Barbor designed) small signal tester.  The customization includes a selectable external input for stimulus, multiple outputs, etc.. This tester is only for use with the most common dual triodes (though a fabricated adapter would allow triode connected small signal pentode comparison at very limited DC conditions). We have this unit connected between an HP 8903B and HP spectrum analyzer to attempt to characterize harmonic distortion at various drive levels, etc. under fixed DC conditions for guitar amp work.

 Regards, Jim

trobbins

Re: Simple Tube Tester?
« Reply #25 on: October 08, 2018, 04:41:00 AM »
And to round out the conversation - I'd strongly suggest a variac and your amplifier and a meter, as your 'valve tester'.

You get the exact bias operating test conditions, and the variac makes sure you don't damage anything.

Remove any amp feedback and you have a stage gain test at the exact operating conditions you want to check with.

Along with simple options of a soundcard and some software you also do valve distortion benchmarking, and perform your own microphony test.

Re: Simple Tube Tester?
« Reply #26 on: February 22, 2019, 04:05:41 PM »
I said I might as well revive this topic ,
I see quite a few microcontrolled valve testers around , but just like Trobbins said above ,they dont test actual in circuit conditions like found in real amps , I like the simplicity of the bias adapter method , for volts and current ,but a means of applying test signals to the grids(ac&dc) would also be great , an abillity like mentioned above to measure harmonic content of the output would only require load resistor /REW at the back end . Reading of the volts, currents need not be automated into the pc ,a simple pen and paper would suffice , the data could be punched in later and graphed up .

What I'm thinking is a  box ,hammond die cast type , a built in variable source of negative grid supply ,possibly battery opperated  , current and voltage output to any old digital meters you have lying around , switchable inputs to grid for test signals .either sound card generated or from a conventional bench sig gen/ arb etc .One switch to select the tube 1,2,3,4 for which current and voltage will be measured , then another to switch the electrode your measuring . a pot for varying the grid bias , and maybe shorted input jacks with dc blocking caps to the grids of the tubes . I cant see any real reason it needs to be any more complicated that this .

All the other modern testers Ive seen are single tube at a time apart from the maxitester2 , and they all have internal supplies designed in . There are some nice features on some of the kit testers , little enhancments ,electrode short and gas fault indicators  ,simple to do  and very very effective for weeding out duds . Im sure many of the vintage testers had similar simple fault finding indicators so you can choose not test a particular specimen any further and risking damage to your apparatus .

I see one or two have made their own test jigs here ,any inspiration greatly appreciated .

Re: Simple Tube Tester?
« Reply #27 on: February 22, 2019, 07:07:10 PM »
I was just thinking about a grid supply , batteries say a 9 volt would require maintenance,wouldnt last very long  and involve some fairly ugly switching hash to generate the 50 or more volts required .
What if you picked up 6.3volts ac from one of the heater sockets on the amp ,then back in your test jig box install a small low volt transformer in reverse to step up the volts before the usual recification,smoothing and dc voltage adjust to grid neg voltages
Certainly would make it a breeze install , no external mains or battery power source needed ,totally powered from the amp your testing , and you know your bias voltage is always present as soon as the Lt on your amp is energised .

A small 6 volt transformer using a single 110v tap primary might be in the right ball park for the job allowing for some losses ,only requires small current anyway , a balance  and current adjust control like in the reference below looks like a nice addition ,only requires  an extra pot ,now we can effectively zero out imbalance between push pull pairs , at one point on the scale at least , a null test by driving both grids in phase could also be interesting for test purposes .

https://www.vtadiy.com/book/chapter-5-power-supply-unit/5-3-power-supply-for-the-fixed-grid-bias/

I have a bunch of NOS russian ceramic multi wafer rotaries lying around for decades , should be just about right for the job.
I think 1 or 10 ohm resistor are usual as cathode current shunt  ,maybe increaseing the wattage and heatsinking of these resistors could be a good plan ,then there should be no need to worry if the amp is driven while on test or not , I see the Weber bias rite uses copper tubing , I might try a small metal clad resistor heat sinked to a lenght copper pipe to make the adapters .

Makes sense to provide a sheilded cable for the  driver stage  output and grid inputs from and to  the amp socket adapters 
 When output stage  test signals arent  required i could  have it so driver output  is routed back to  power tube grid via shorting jacks, only bias control remains in the test jig .

Wow that all seems to good to be true , everything I need in  a simple passive switch box, external metering and signal source means it fits in just fine  with any bench setup ,no micro processors  to go wrong , only electronics involved is the transformer bridge and bias  circuit which can be passively smoothed .

Below find added a general idea of how it might look ,
Im a bit unsure about all the interactions in the cables ,or how best to minimise them , cathode current is of course measured as a voltage, 1mv corresponding to 1ma with one ohm resistor , would stopper resistors do as a current shunts to measure grid and screen current also ?
If everything could be read in voltage mode on an auto multimeter it would make it quick and easy to opperate ,the meter would autorange to the most appropriate range for the voltage drop/currents your measuring and give a meaningfull reading in mV for mA on screen  or cathode  current ranges. What would be the most appropriate resistor to set the scale for grid current measurement on the multimeter?
« Last Edit: February 23, 2019, 12:55:29 AM by Tubetec »

Re: Simple Tube Tester?
« Reply #28 on: February 25, 2019, 09:19:07 AM »
I found this bias circuit ,almost exaclty as I had described , only I might as well go full wave bridge config , so 50 hz is less of an issue . Easy to add some rc sections to it also ,might give a 12 volt transformer in reverse a shot off a 6.3vac winding and see what I get out ,exact voltages dont matter .



Re: Simple Tube Tester?
« Reply #30 on: February 27, 2019, 02:01:00 AM »
Thanks for the links Lukas, looks good .