Vacuum Tube Testers

PWRRYD

Bill S. (4th try) and I had a discussion about vacuum tube testers at breakfast in Iowa.  Sounds like he scored a very nice Heathkit tester at a local swap meet.  A number of years ago I found a tester on the local craigslist, met the guy and bought it for $30.  It powers up and it appears everything is there, it is just very worn from use.  I'm wondering if it's worth it to have it calibrated ($200).  Do a search on Ebay for TV-7D/U to see what these things are going for.

Bill,

What model Hickok did you say was the Mac Daddy of testers?

Here is a couple pictures of my tester:

4thtry

This is one of the most rugged testers available (the TV-7 series).  My understanding is that these were the testers contracted by the military for use in battle.  They are super rugged.  Fair Radio Sales uses a calibrated TV-7 to test tubes for customers buying used tubes.  The first time I stopped at Fair Radio Sales (Lima, OH), they had a re-built, fully calibrated TV-7 for sale for roughly $600.  I believe, but am not sure, that the TV-7 is a true "trans-conductance" type tube tester; not one of the less expensive emission type testers.

I am by no means an expert on tube testers.  I've basically spent some time on the web the last few years studying different types of testers.   The Hickok 539 series (types A, B, and C) are the most expensive, and the most sought after tube testers available.  If in good shape, they go for roughly $1500 on ebay.   You can send one of these off for calibration for about $200. 

In talking with the technical staff at Fair Radio, they advised me to look out for bad Bias control pots on Hickok testers. On some models, Hickok used a bias pot with a custom taper (not linear or audio), and if this control goes bad, the only way to fix the tester is to buy another tester of the same type and then pull out the bias pot.  So before spending any money to calibrate your tester, you should check all the pots to make sure they are still in good shape.  Also, do a web search for threads on the TV-7 series tester to see if there are any other issues that need to be addressed before calibration.

PWRRYD

I found a website that has step by step instructions on how to calibrate it just like the guys asking $200 do.  Looking at the schematic there are only two internal vacuum tubes and the caps are all film type not electrolytic.  So dirty selector switches and pots seem to be the only concern.

4thtry

Sounds like a great project.  You should have a very nice tester when you get done.  My Heath-kit has calibration instructions in the assembly manuals, plus I found some additional calibration notes on-line.   I plan to DIY my calibration as well.   When we get done, we'll have to bring our testers to one of the DIY events for a show & tell session.  

PWRRYD

That would be an awesome double check for our testers!  

ani_101

What language are the guys talking???

Wolf

"Archaic", likely a language of the formerly 'Lit'.