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In Reply to: Re: Really really dumb question about testing the 83 in my tube tester posted by Chris Haedt on November 04, 2002 at 14:28:16:
A properly made SS replacement will NOT have resistors in series with the 83. Quite frankly, if the one you made had them, you did it wrong. And of course the series resistance will change readings with current draw.A properly made SS device works VERY WELL.
Plus the 83 tube is not plentiful anymore. Maybe at one time, but not now. I have 45 of them, and that may be the largest stash anywhere. Our friends at Antique Electronic Supply now show "Call" in the price column for 83s. That's not 'cause they're overstocked.
Follow Ups:
The 83 replacement I tried, was as suggested by Alan Douglas in his book on tube testers. The device consisted of two 1N4007 diodes and two 10 ohm 2 watt resistors. I tried it in a number of testers and got variable results. Another problem with one tester, was that without the load of the 83 filament on the transformer, the line adjust circuit no longer worked properly. Would have had to add a big power resistor to the line adjust stat to set the tester to line. Based on these two issues, I just recommend that people stick with the 83 tube, and so does Wendell Hall. When I buy 83's, I buy them used and got the last ones for under $10 each. Used tubes are fine for this application--they are cheaper and likely to offer stable operation.
Chris,The 10 ohm resistors make an "artificial center tap" replacing the connection that used to be made by the 83 filament. They definitely are not in series with the 83s voltage output.
I have had a few cases where without the resistors (just subbing diodes) the line adjust was off scale. But not one single case of a problem when the resistors are in place. Could there have been a wiring error in the SS piece?
I've used SS "83s" in my TV-7s for many years, they work great, the testers stay cooler, and they provide enough "oomph" that I can (with care) even test a 6336.
I've calibrated 'em many times as well, and they always calibrate perfectly.
FWIW.
Chris -I've replaced 83's in many TV7's and 539b/c's and all have worked nicely in my experience. It's the 5Y3 that really can't be solid-state. Just curious which tester's gave you problems?
As a side note, please dispose of any dud 83's properly (look for a place that accepts fluorescent lamps).
I tried the adapter that Alan described in a 600A and detailed the results in the article on the subject at www.hickoktubetesters.com Yes--the resistors form a center tap. I know the adapter was correct and it did work--it just did not work the same as an 83 tube did, and this difference was not the same for all tubes. Now, if you don't care that the results you obtain may vary by 10% sometimes from what an 83 would provide--then use the adapter. I cannot remember what model Hickok would not set to line with the adapter--might have been a 6000. There was variation in the line adjust pots used by Hickok--so some models have greater range of adjustment than others--and my high AC line voltage (125 volts) is not what everyone may have.The bottom line on this is that you can get a used 83 for $10 and that this tube will let the tester operate the way it was designed to work. My data suggest that solid state adapters do not work the same as an 83 tube does, and the roll chart data is based on an 83 tube in the tester. So--to sub for a $10 part you are introducing additional error into an area that is none to precise to begin with. Based on this--I do not think this is a practical improvement. Send me a solid state adapter that provides the same results as an 83 in the tester and I will change my mind--I am open to suggestions here.
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