Test Seeburg 2050 tube on Sencore Mighty Mite

The 2050 Gas Thyratron tube is a tube used in many Seeburg jukeboxes.  Even though a 2050 tube is not listed on the setup charts of Sencore Mighty Mite models TC162 and TC28, you can test them.

Settings are 6-A-5, socket #1.

The key to a proper test is that you MUST engage the LIFE TEST during emission testing to reveal a substandard tube that will not reliably handle the current levels needed.

Here is an example of testing a weak 2050 tube in a TC28.  Notice that the first picture, you may think that the tube is good because the emission is strong.  However, the 2nd photo shows that with LIFE TEST engaged, the emission drops to almost nothing.  This is the key to testing ANY tube in a Mighty Mite, but especially for any power tube, thyratron tube, or rectifier tube.

Testing 2050 without engaging LIFE TEST, fails to reveal a substandard tube

Testing 2050 and engaging LIFE TEST, finds the weak 2050 tube

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FM1000 tube testing on BK 707-700

I was asked by a reader named Henry if I knew of B&K 700-707 test settings for FM1000 tube.

FM1000 is a unique Heptode detector oscillator, and as such really does not lend itself to “tube testing.”  It is best tested in-circuit.

That said, you can perform some basic checks on a FM1000 tube for shorts, leakage, and basic emission with your BK 700 or 707.  Using the bottom emission test panel, heater at 6.3v, Sensitivity at around 38, bottom switches set at 1, 8, 12, 2.

I asked Henry try testing an FM1000 tube to verify those settings, and his feedback is that they do work.

Sencore Mighty Mite chart data EAF801

Simon Flint from Australia contacted me today because he noticed that the Sencore Mighty Mite setup data for the diode section in tube EAF801 (which is an RF Pentode with Diode section) did not appear to be testing the diode section properly.  He wanted to know if I could investigate.

I examined the Telefunken datasheet for EAF801 and have determined that the Sencore setup data for this diode section of the tube is wrong.  It places far too much load on the diode, causing the meter to incorrectly read low emission.

The EAF801 diode section is only rated at 0.7ma according to the Telefunken datasheet, therefore the chart setting (D load) will draw far more current than the EAF801 diode can handle.  In fact, extended testing using this incorrect chart data will ruin this diode section.

My analysis suggested that Load G is the correct load for the EAF801 diode section.  Simon tested this load, and has verified that my analysis is correct.  Thanks to Simon for diligently testing the new load setting and verifying that it is now correct.

So for the diode section (only) for EAF801, the load should be G…not E.  Make a notation in your chart to reflect correct load (the 2nd line of the setup data for EAF801).  Purchases of my TubeSound Sencore mighty mite setup book will have this factory mistake corrected if purchased after March 12, 2021, and the correction will “look factory”.

FOR SALE- Philco 20 Deluxe cathedral tube radio

Here is a gorgeous PHILCO model 20 DELUXE tube cathedral radio.

This radio is from my own personal collection.  I have owned it for close to 30 years.

Price is $225 + shipping (or pickup).  Working condition.  Awesome cosmetics in my opinion, a real beauty.  (Output tubes and rectifier tube will be different from the ones you see in the photo.)

Safer double-boxing of this radio will end up making the shipping cost somewhat expensive (due to the weight of the radio and the resulting large size of the outer shipping box.)  If you are a penny-pincher regarding shipping costs, then this item is not up your alley.

Q&A regarding different micromhos scores

Hey Tubesound,

Hoping you can answer a question for me. I have an Amplitrex and a TV-7D/U tube tester.  The Amplitrex tests a 12ax7 as new at 1600GM.  According to your TV7 GM calculator, I believe that should translate to 64 on the TV meter.  However, when I test the same 12ax7 on my TV-7 the meter only hits 42.  Does it sound like my TV7 needs some calibrating or am I missing something? Hope you can help and thanks for the great calculator.

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