Greetings, Is there any way to check for tube shorts with a multimeter measuring pin to pin? Or does there have to be a current flow as in a tube tester. All I want to do is verify that the tester (philco 7050)is indeed working.
Thank you,
Vinny

Sometimes yes, Sometimes no, depends on a few things. If the tube has a heater to cathode short, it may not show up until the tube gets to temperature. If it's a good solid short, then an ohm meter will show it too. On some testers a tube that is gassy will show up as a short also. You can always check with an ohm meter though, elements that should not be touching anything else inside.

Hi Vinny,
I have done it. With H-K shorts, however, it is difficult.
One class of shorts, cold heater shorts can be measured with an ohm meter. They are rare, but I have a 12AT7 here that has one. It caused a radio to explode (35C5 and 6BJ6 shattered). Good thing they are rare.
I have a 19T8 which had a short between its cathodes. When running I can measure around 1 meg between the cathodes.
If you want to get a good idea of where an H-K short is and where it is located, this can be done. Run the tube off of DC at it normal voltage. Connect a current meter from cathode to ground and take a reading. Then connect the current meter from cathode to filament positive.
I am assuming here that the H-K short isn't so severe as to damage the current meter. Usually they are not.
Using ohms law you can get an idea of how severe the short is, and where it is located on the filament.
I had a 6F6 in my Zenith 5S127 with an H-K short. The cathode is grounded, and the short was near the side of the filament that is grounded. Because of this the tube is not a problem. It worked OK and didn't overload the power supply. It was like that for quite a while. Several months ago I tested the tube again and the short is gone.

Best Regards,

Bill Grimm

About an hour ago I tested a philco model 45. It had a 80GT tube in it. It powered up, hummed then blew the fuse. I tested the 80GT, initally no shorts, after 1 minute shorts between plate and filliment. I let it cool down and the short went away. interesting tube though it has the envelope of an eye tube, and plates that look like a 6ca4, and I can see a cathode around the filiment. There is a hole melted through the cathode. The radio had a bad power transformer when I got it,luckily it dosent need another one after today.

:Hi Vinny,
: I have done it. With H-K shorts, however, it is difficult.
: One class of shorts, cold heater shorts can be measured with an ohm meter. They are rare, but I have a 12AT7 here that has one. It caused a radio to explode (35C5 and 6BJ6 shattered). Good thing they are rare.
: I have a 19T8 which had a short between its cathodes. When running I can measure around 1 meg between the cathodes.
: If you want to get a good idea of where an H-K short is and where it is located, this can be done. Run the tube off of DC at it normal voltage. Connect a current meter from cathode to ground and take a reading. Then connect the current meter from cathode to filament positive.
: I am assuming here that the H-K short isn't so severe as to damage the current meter. Usually they are not.
: Using ohms law you can get an idea of how severe the short is, and where it is located on the filament.
: I had a 6F6 in my Zenith 5S127 with an H-K short. The cathode is grounded, and the short was near the side of the filament that is grounded. Because of this the tube is not a problem. It worked OK and didn't overload the power supply. It was like that for quite a while. Several months ago I tested the tube again and the short is gone.
:
:Best Regards,
:
:Bill Grimm
:

Hi Vinny

You could check for direct shorts with a meter but most shorts/high leakage only show after a tube warms. It's not worth checking for shorts with a meter. Too msny combinations and almost no tubes will fail this test.

Norm

:About an hour ago I tested a philco model 45. It had a 80GT tube in it. It powered up, hummed then blew the fuse. I tested the 80GT, initally no shorts, after 1 minute shorts between plate and filliment. I let it cool down and the short went away. interesting tube though it has the envelope of an eye tube, and plates that look like a 6ca4, and I can see a cathode around the filiment. There is a hole melted through the cathode. The radio had a bad power transformer when I got it,luckily it dosent need another one after today.
:
:
:
::Hi Vinny,
:: I have done it. With H-K shorts, however, it is difficult.
:: One class of shorts, cold heater shorts can be measured with an ohm meter. They are rare, but I have a 12AT7 here that has one. It caused a radio to explode (35C5 and 6BJ6 shattered). Good thing they are rare.
:: I have a 19T8 which had a short between its cathodes. When running I can measure around 1 meg between the cathodes.
:: If you want to get a good idea of where an H-K short is and where it is located, this can be done. Run the tube off of DC at it normal voltage. Connect a current meter from cathode to ground and take a reading. Then connect the current meter from cathode to filament positive.
:: I am assuming here that the H-K short isn't so severe as to damage the current meter. Usually they are not.
:: Using ohms law you can get an idea of how severe the short is, and where it is located on the filament.
:: I had a 6F6 in my Zenith 5S127 with an H-K short. The cathode is grounded, and the short was near the side of the filament that is grounded. Because of this the tube is not a problem. It worked OK and didn't overload the power supply. It was like that for quite a while. Several months ago I tested the tube again and the short is gone.
::
::Best Regards,
::
::Bill Grimm
::
:

Warren, Bill G, Ian, and Norm,
Thank you so much, your knowledge and ability to convey it is priceless. Another great lesson learned.
Vinny A.