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Re: [TenTec] Solid state amps

To: tentec@contesting.com
Subject: Re: [TenTec] Solid state amps
From: Bill Fuqua <wlfuqu00@uky.edu>
Reply-to: tentec@contesting.com
Date: Mon, 08 Dec 2003 12:46:54 -0500
List-post: <mailto:tentec@contesting.com>
Interesting item. By coincidence I am working on a power tube tester today. I built one some time ago to check 4CX250B tubes because we go thru a lot of them here. I built a pulse tester that basically applied a large negative cut off voltage to the grid and then switched it to zero for a few microseconds and measured the pulsed plate current. This worked just fine but if the tube arced over I had to replace the hard to find high voltage P channel MOSFETS. So, I have gone to a different grid pulsing technique that uses a more common N channel MOSFET and is transformer coupled to the control grid. It seems to work great even with positive grid pulses over 2 amps. Now I can use it to check high mu triodes as well. I have lots of RF power tubes at home and this way I can test them with out having to have an amplifier. Even though the plate current may be several amps the DC Plate supply only needs to be good for a milliamp. or so.
I simply compare the results with the data sheets to see if the tube is near spec.. This seems to work with in 10 or 15 percent using a new tube.


73
Bill wa4lav


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