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Duo Vac, New Chinese tube tester?

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BillWojo

Member
Joined 2014
#1
With all the crap going on in the vacuum tube world I thought I'd look into the possibility of starting to test several large boxes of tubes I've collected over the years. I've been intrigued by the latest type of tube testers like the MaxiMatcher that used short pulses at operating voltages that are supposed to give better results than the older style testers. I mean, they sound good and several folks that I know swear by them.
Ok, so I decide to search Ebay for tube testers just to see if anything new has cropped up, suspecting that the Chinese might have copied the design by now. Well, this looks pretty similar, looks like they pulse the tube with high voltage as well and give you a digital readout. All for $320.00!
Does anyone have any experience with one of these?
https://www.ebay.com/itm/1538982236...k06K85RrFv6cohdj|clp:2334524|tkp:BFBMhuLk2vJf

BillWojo
 
#3
It looks like a nicely packaged uTracer clone, but without the big advantage of the uTracer - the curve tracing software (at least i could not see a reference to accompanying software). And uTracer is 30% cheaper, although you do have to fettly your own enclosure, but because of the software it can be minimalistic.
IMG_1837.JPG
 
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#7
Tubekarus75 said:
I am also interested in this tracer/tester system. can you show me some pics of your tester please? what type of tubes are you testing? how does your tube socket holder on your utracer look like? br juergen
Click to expand...
My copy of the uTracer has a separate box for the tube socket. In addition the wiring is done
in a d-sub connector, made for each type of tube. Thus no mistakes cat be done if observing the
label on the connector.

uTracer
 
#12
I do not like pulse testers: With a pulse tester the anode and grids do not get hot as when in a real circuit. In order to test properly you want the tube to be at real operating temperature with expected anode dissipation and I prefer about 5 minutes warm up.
 
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#14
OldHector said:
By pulse tester, you mean the circuit for managing different heater voltages? I have a uTracer, and with that it is easy to use an external AC or DC supply for the heaters.
Click to expand...
I think EL506 is alluding to the fact that in a tester like the uTracer, the voltages applied to the anode, grid, etc. are pulsed, and most of the time there is no voltage on the electrodes. Consequently the current flow in the anode is pulsed too, and so the average power dissipation in the tube is a small fraction of what it would be if the tube were being run continuously at the voltages and currents being plotted by the tester.
 
#15
cnpope said:
I think EL506 is alluding to the fact that in a tester like the uTracer, the voltages applied to the anode, grid, etc. are pulsed, and most of the time there is no voltage on the electrodes. Consequently the current flow in the anode is pulsed too, and so the average power dissipation in the tube is a small fraction of what it would be if the tube were being run continuously at the voltages and currents being plotted by the tester.
Click to expand...
I agree. In addition it enables the possibility to draw curves way beyond the Pmax area and
the positive grid area.
 
#16
cnpope said:
I think EL506 is alluding to the fact that in a tester like the uTracer, the voltages applied to the anode, grid, etc. are pulsed, and most of the time there is no voltage on the electrodes. Consequently the current flow in the anode is pulsed too, and so the average power dissipation in the tube is a small fraction of what it would be if the tube were being run continuously at the voltages and currents being plotted by the tester.
Click to expand...
And as such the measurements are next to useless for matching, characteristics change when the tube is fully heated up. The best way to match a tube is to test them at the voltage and dissipation levels that they would have in the actual circuit. And then do not forget to test at a slightly higher and lower filament voltage either to see if they still match.
 
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