How to repeat FUNKE W19 tests on a Hickok 750
The Funke W19 is one the most used tube testers for those who use European tubes. Reasons are many. The tester is extremely reliable, very precise, works with a stabilized voltage, the card system prevents setting errors. Well there are more reasons for the hardware. Next is, the software is very good. Test results are recogniszed by anyone, and you will almost never find a tube missing.
To repeat a Funke W19 test is easy, but it helps a lot of you know what that is To give you an idea, do the following:
Set the Hickok 750A for testimg a 5U4G rectifier. See if it works nice, and if the rectifier is good. When yes, that means at 100mA DC Plate current it should have 20...40Volt DC on one plate. You can check this from the tube curves of the 5U4G. How to verify this? Set the function switch to "H", but before you do, rotate the knob for voltage regulator tubes all counterclockwise. So set the switch to "H" and nothing should happen. Now, slowly turn the knob for voltage regulator tubes clockwise, while you push the switch beneath it to "Mils" (Than means miliampere). You can continue until the meter reads 100mA. Now let go the switch, and you'll read the voltage belonging to it. So, 20...40Volts and the tube is good.
Once you understood (exactly!) what you have been doing and how that works, you can try the same for the 6SN7. So test a 6SN7 at first the normal Hicock way. When the 6SN7 is good, do the following :
This method is extremely reliable, and there is more behind it as one might expect. The tube is tested at a lower voltage than normal, at higher current than normal, and the grid is at 0V because we are not interested in transconductance. We only want to know what teh cathode can do, under harder than normal conditions. With some practice, you can even derive the settings from a normal datasheet. For that, take the 6SN7 tube curves, look at the 0V curve, and figure out what Funke has been doing. This is for specialists only. When you are new to this, you should use the Funke blue book, and test cards.
So NOW YOU CAN TEST European tubes, and any USA tube that are not on the roll chart. You just need to buy on Ebay, a pdf copy of the Funke W19 cards. Costs you appr 15 Euro. Additional you need the Funke blue book which is an amazing piece of standard work, linking almost every tube on the globe to a test carrd. The book is appr 30...50 Euro. The Funke cards are 100% complete, there is no tube missing.
WHEN YOU HAVE A HICKOK 750A THIS IS REALLY WORTH UNDERSTANDING IT.