Original roll chart. 605A/Tube Testers/© The Hickok Instrument Co. Consolidated Test Data for Hickok Model 533A-600A-605A Tube Testers.
Hickok Meters
On the Hickok roll chart for the GM value there is a number for each tube exept diodes. The Hickok book says this number is the average tube value period. I see people saying this number is the minimum good value, New average tube value. I see saw one person who listed a tube at the roll chart value 3600 as the new tube value of a 6hr6 tube and listed the minimum 2160 as the min for this tube.
I can not find any info of the min value for any tube. Can any one tell me how this 2160 min number is possible.Thanks. I believe that the RTEA or what ever that organization was called.(Radio Television Electronic Association ).that 65% of the new tube reading was minimum for a ' good tube.'
So.3600 minus 35%.is not exactly 2160.but close. Looks to me that is should be about 2340?( This is not exact information.but somewhere in the ballpark.)I've got a Weston tube check.and it lists the GM value at which a tube is considered not good.I've never done the reverse math to see what percentage that is of GM for a new tube. Click to expand.I just read a article Chris Haedt wrote back in 2002 called Testing the 12AU7 on Various tube testers. Its about testing a 12au7 tube on multiple testers and he states the the reject point on a 12au7 tube is 1430 which is 65% of the roll chart value of 2200. So knowing this fact solves all my problems for min tube values of any tube on the chart. Leland47 I just ran with your info and found this article. The tube they tested was NOS from a lab.
It tested around 2400 to 2500 which make me really think the tube chart is a average new tube value. Hi Chaztaylor, I too have to learn a lot about this area.
Hickok Cardmatic Tube Tester
IMO.I don't think there can be a absolute value for a new tube. Those gmhos values are 'Average of new' so there is a range. The other trick with a Hickok 6000 or 600 is that to read the gmhos values you use the three red dots and choose the one appropriate to your range, and not the English value on the roll chart, which is for Good/Bad green/red testing only. For a 12AX7 you'd set it to the red dot for 3000 since the value given is 1250 and read the meter.Also, values vary from brand to brand and tester model within brands too, which is why there are no definite values for new tubes. 65% is a good minimum ballpark; but if you have a marginal tube that tests on the edge of green, you could take a gmhos reading on it and use that as your baseline.