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 Post subject: Some questions about a Philco Model 7051 Tube Tester
PostPosted: Mar Mon 05, 2018 11:23 pm 

Joined: Jul Mon 24, 2017 3:27 pm
Posts: 146
Location: 01450
Just a heads-up: I have never used a tube tester before. So anyway, I bought one of these at a swap meet and have a couple of questions. The only tube I have to try out is one working and one non-working 35W4. The non-working one has an open-circuit between pins 4 and 6, so the filament is burnt out there. Is that something that a tube tester would find?

They both pass the short test and they both apparently pass the quality test. I say 'apparently' because I'm not sure I am reading the instructions right. For the short test the instructions say that the switch positions in lower case should be set before plugging the tube in, and then the ones in upper case should be set inidividually afterwards - returning them to the center position before moving on to the next one. For the quality test, all the switch positions are in upper case. So do I plug the tube in before setting them, or after? I ask, because if I plug it in before setting them, then the needle doesn't move when I set each switch and push the knob over to 'quality'. If I plug the tube in after setting them, then the needle hits the end stop in the 'Good' section when I push the knob over to 'Quality'. Even though I know that one of the tubes has an open circuit.

There is a timing issue here maybe. I have to let the tube filament start to glow before I can get any movement out of the needle, but with all the switches at their neutral position, the filament doesn't glow.


 Post subject: Re: Some questions about a Philco Model 7051 Tube Tester
PostPosted: Mar Tue 06, 2018 3:26 pm 

Joined: Mar Sat 03, 2007 12:53 am
Posts: 688
It is good practice to set switches in a tube tester before you insert the tube to avoid any possibility of burning out the tube. For example applying 35 volts to a 6 volt filament will burn out the filament. It is also good practice to perform a short test prior to performing an emission or a transconductance test to avoid burning out the meter in the tube tester. If the short test fails an emissions or transconductance test should not be performed. The tube needs to be warmed up before an accurate reading can be taken.

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