[Hallicrafters] Re: Testing Transmitting Tubes

[Paul Bernhardt]

Kenneth,

This is the way I match tubes.

I adapted a vacuum tube curve tracer to test and match transmitting 
tubes.  The Tektronix 577 curve tracer puts out up to 1400 Volts for the 
Collector/Drain/Plate voltage.  The Gate voltage steps are only 1 Volt.  I 
built a High Voltage Amplifier that multiplies this voltage to give 10 Volt 
steps for the grid.  Also, I added a filament supply that provides 2.5, 5, 
6.3 and 10 Volts at 10 Amps.  With this, I have been able to test 813, 211, 
6L6, 6146, ... tubes.  Tetrodes, and Pentodes are tested by adding a 
separate fixed supply of 150 or 300 VDC for the screen grid.  The sockets 
are used in pairs so that one can switch between the two tubes under test 
to compare characteristic curves.  I demonstrated this high power curve 
tracer at the MRCA meeting one year ago.

Don, can you post this on the other mail lists? I don't subscribe to them.

Sincerely, Paul Bernhardt

At 05:10 PM 9/21/2004, Kenneth Ketner wrote:
>Since I work with sweep tubes in Swan rigs and similar units, I had tried 
>to think up a way to match tubes. I have a Hickok 600A for older tubes and 
>a 6000A for later types.
>
>My solution was to take a piece of 1.5 inch clear plastic tubing cut to 3 
>inches in length, push a round back 100 ma meter into the top of it, with 
>two wires coming out from the meter pins, the meter then non-destructively 
>connected in the plate circuit when the tube is tested.
>
>I working on some Galaxy V rigs, I replaced some finals with tubes matched 
>closely to the current read by this setup (when the TEST button is 
>pushed). The tubes "matched" by this method performed very well in the rig.
>
>I have been too lazy to measure the plate voltage put on the tubes during 
>this test.
>
>Anyway, could this be a useful matching method?
>
>Merz Donald S wrote:
>>A point of clarification, the high-end Hickok tube testers will test many 
>>transmitting tubes. 807, 1625, 811A, 6146, 801A, 809, 826, 829 and many 
>>others. I have a Hickok 752A and use it all the time for these tubes. I 
>>hear that the Hickok 539-series also works.
>>But higher power tubes are more problematic, with plate voltages in the 
>>1000-2500 volt range. For these larger tubes, I just have a sense that 
>>there is a creative and easier solution here that I am missing.
>>73, Don Merz, N3RHT
>>
>>-----Original Message-----
>>From: Merz Donald S Sent: Monday, September 20, 2004 10:20 AM
>>To: 'Amradio (E-mail); 'Baswaplist' (E-mail); 'Glowbugs (E-mail)
>>Subject: Testing Transmitting Tubes
>>
>>Has anyone built a transmitting tube tester? Or seen any plans on the 
>>web? The only thing I have seen on this subject is the issue of GE Ham 
>>News that covers the subject (Vol 6, #3, May/June, 1951). I have some 
>>power supplies I can use to run the static test. But I need to build 
>>something to hold the tube sockets, filament transformers and plate 
>>current meter. I hate to reinvent the wheel and would be happy to follow 
>>a pre-existing design if I could find one...
>>Any ideas?
>>73, Don Merz, N3RHT
>>
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>--
>
>Ken Ketner
>ARS KA5ELD (Extra Class) GQRP # 809
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