[R-390] Tube testers

[Bernard nicholson]

Guys tube testers are for wimps  the best tube tester is the circuit that the tube is working in , you can check the voltage drops across plate&screen& cathode resistors and with a modicum of mental arithmetic [remember that?] you can easily see what is happening in a circuit, in a well designed radio tubes don't work very hard at all !  The original signal Corps Specs for the RCA  AR88  calls for the set to perform to its specification with ANY or  ALL tubes at 30% emission   This is the reality ! this is the reason that tubes are rejected on the tester but the set is still working OK,  I was trained in communications in Carrier Telephony  , we used to keep detailed maintenance logs of every piece of equipment And performance checks were done regularly this gear used literally thousands of tubes  and many tubes were only changed after many years when the specs were no longer achieved, Back in these times  people who resorted to tube testers were called Valve or Tube Jockeys,  They were looked down upon and were figures of fun .   Tube testers were used in Australia as a marketing tool , you could take all the tubes from your radio or TV and test them in the shop where they could sell you some more, Very convenient !   Surely if we have Pretensions to own and Maintain an Esoteric R390A  one can learn about mutual conductance and amplification factor Ect   then all you need is a voltmeter Regards to everyone  and keep the posts coming .