[madghost]

I obtained a Heathkit tube tester model IT-17. I wanted to test my Philco 41-290 tubes but the tube chart on the tube tester does not include the ones Philco uses (it has only a few of the item 7 series tubes). I tried to find a tube conversion chart that would allow me to substitue the item number for the actual tube. In other words, if I find a substitute tube number for a 7C6 on the chart, can I use the tube nomenclature of a sub to test my 7C6? Also, I have been trying to find a satisfactory tube conversion/substitution chart on the Internet, but so far no real luck in getting a complete and full listing. Any help in either of these two items would help greatly.
Thanks much!

[Doug Houston]

It may be possible to find a conversion chart for your Heath tester. They were made for newer tubes and, as with many testers, there may not be a chart that takes you back that far.

The best thing is to get a better (more expensive) tester that takes in the older tubes. All this, if you're really serious about radio work. I use a Hickok 539C tester, and it has a special book that goes back to "obsolete types" into the era of the 20s and 30s. With all of the tube types that came along, it's amazing that any tester can cover as much as many of them do.