When I first started using the Heath tester I always reset the line twice; once in the leakage test position, and again in the tube test position (which has plate current flowing). The Heath manual does not say to reset the line a second time, and neither does the manual for the Weston 981. So--I stopped resetting the line in the tube test position.<P>In checking a machine that tested a 6CA7 low, I found that the filament voltage was well under 6-volts. This was corrected to 6.1-volts when the line was reset in the tube test position, and the tube tested normally. Seems now to make more sense to reset the line a second time--despite the fact that the manuals do not specify this. Comments? Hard to imagine that both the Weston and Heath manuals failed to mention the second line reset. <P>------------------<BR>

Hi Chris,<P>The only calibrated function in the tester is the qualitative test, i.e. with plate current flowing, so that's where I adjust the line. I don't worry about the setting for other tests. Just one carbon-based lifeform's opinion <IMG SRC="http://antiqueradios.com/forums/smile.gif"><P>------------------<BR>73 de Leigh W3NLB | | Leigh@AtwaterKent.Info<BR><A HREF="http://www.AtwaterKent.info" TARGET=_blank>http://www.AtwaterKent.info</A> | | <A HREF="http://www.Synchrophase.info" TARGET=_blank>http://www.Synchrophase.info</A>

Alan Douglas'book;"Tube Testers and Classic Electronic Test Gear" has a section on page 10 covering resetting the line adjustment.<BR>Alan warns that Hickok never recommended resetting under load as you may get misleading results. The GM readings given on the Hickok roll chart apparently take into consideration the drop in heater, plate,screen and other element voltages.<BR> His book is a "must have" if you are going to work on test gear, especially tube testers.<P>Ron<P>------------------<BR>

Alan's book is excellent. You don't reset the line with most Hickok testers--you *do* reset the line with the 539 series. 539's have separate line and a bias meters so that the voltages can be adjusted with plate current flowing. The Heath is an entirely different design, and has little in common with Hickok testers.<P>------------------<BR>

Hi Chris,<P>I just realized I omitted the tester model from my previous post. It's a Hickok 539C.<P>------------------<BR>73 de Leigh W3NLB | | Leigh@AtwaterKent.Info<BR><A HREF="http://www.AtwaterKent.info" TARGET=_blank>http://www.AtwaterKent.info</A> | | <A HREF="http://www.Synchrophase.info" TARGET=_blank>http://www.Synchrophase.info</A>

If actual filament voltage at any of the tube sockets is not the determining factor as to whether resetting is needed,what then,*is* the determining factor?<BR>Malcolm<P>------------------<BR>

The determining factor is usually the instruction manual for the gear you are using. Seems like the one for the TT1 has to be wrong. This is one of those times when it would be great to be able to talk to the people who designed the stuff.<P>I had occasion to measure the plate current when testing a 6550 on the TT1. Wow--it tests the tube at 80+ mA. Not too many other testers like that--no wonder the transformer sags! <P>------------------<BR>