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 Post subject: Hickok Tube Testers and the SS 83 Rectifier Conversion
PostPosted: Sep Sat 11, 2021 5:25 pm 
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Joined: Oct Thu 29, 2020 10:17 pm
Posts: 173
Location: Centennial, Colorado
I started a new series on this controversial topic, since there is more to consider than just what is generally discussed. Potential buyers of most Hickok tube testers should consider reading this post.

Generally the discussion revolves around the cost, availability and reliability verses the benefits of converting. As has been stated here many times the cost and availability of the type 83 tubes is not really a factor at this time and the reliability is very good.

So why would anyone even consider converting to solid state?
There are several reasons that should be considered before scoffing at the idea.
Heat is being captured within the case, which for some models it cooks the meter and that is reduced or eliminated with SS.
Unbalanced rectifier elements over the full range of current requirements is eliminated with a SS conversion.
Reliability is very good, but even better with well designed SS.

In my opinion a good 83 SS replacement should use 2 1N4007 rectifiers in series along with a 10 Volt 5 watt resistor for each side of the dual rectifier. I would also rule out the fuse due to reliability if the the current rating is close enough to protect the main meter. I use the same configuration for the 5Y3GT conversion except the zener is replace with a 680 ohm 1 watt or better. In most cases I use filament load resistors of 4 ohms a total of 8 ohms reducing current to 650mA for each tube.

One very important factor that is often overlooked is the stress on the power transformer. The 83 filament draws 3 amps at 5 volts, which translates to150 mA or more depending on the model in the primary not counting transformer loss Many of these transformers are already struggling now that they have aged. Personally I have converted the 5Y3GT at the same time, which has a filament draw of 2 amps at 5 volts.

If the fuse lamp glows at all while testing a 6L6 tube I can assure you the transformer is already suffering. Even a KT88/6550 should not do much more than a dim glow. Keep in mind that the type 81 fuse lamp used has just a fraction of an ohm resistance when cold. Its in series with the transformer primary of a much higher impedance, hence all the voltage is across the transformer. It operates much like the dim bulb some use for powering up an old radio. However if the transformer current is too high due to load and transformer losses the 81 lamp will start to glow as its resistance increases. It’s a great early warning sign that something is wrong with either the tube being tested, operator error or the tester itself has issues and one of these may very well be the transformer.

For those looking to buy a Hickok tube tester make sure you see a power tube being tested. As I wrote this I looked on ebay where a 752 and a 580A were shown testing tubes. Both clearly have transformer issues and since the 580A is already solid state its truly a parts unit looking for transformer or transformers. It would be questionable if a solid state conversion would help the 752 that much and it may have already been converted. So those that might be tempted to make a purchase step back and realize what your getting into.

Bill


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 Post subject: Re: Hickok Tube Testers and the SS 83 Rectifier Conversion
PostPosted: Sep Mon 13, 2021 8:30 am 
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Joined: Dec Sat 28, 2019 4:18 pm
Posts: 1091
Location: Corinth, TX
Bill, I have a 752A up and running, an old, working I-177B, and a couple of beat up (mostly needing cabinet work) 600As to be worked on.

I am leaning toward the SS conversions, mostly for the reasons you mentioned.

John


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 Post subject: Re: Hickok Tube Testers and the SS 83 Rectifier Conversion
PostPosted: Sep Mon 13, 2021 1:30 pm 
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Joined: Aug Mon 04, 2014 9:42 pm
Posts: 154
Isn't 580A supposed to have the fuse lite dimly illuminated during normal operation? Mine does, and I saw this thread from a while ago:
viewtopic.php?f=8&t=426


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 Post subject: Re: Hickok Tube Testers and the SS 83 Rectifier Conversion
PostPosted: Sep Mon 13, 2021 2:11 pm 
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Joined: Mar Sat 14, 2009 5:56 pm
Posts: 4626
Location: VA 22602
I’ve considered the change from time to time but my major concern is how the solid state conversion may affect calibration. I do know my I-177b’s, 550X and 800A testers have very hot panels after a long session of testing. Each tester was hand calibrated by Hickok employee’s to be pretty close to exact specs prior to release. How consistent are the operating voltages using the suggested dropping resistors across the range of Hickok testers or is the resulting voltage not that relevant? I have four units in service and two in my repair queue.
A note on the type 81 lamp as a fuse. The domestic sourced 81’s are the most reliable. The newer Chinese production lamps will normally have a low glow just with the tester on with no load. I have tried some and have not had a failure of the lamp when testing high current rectifiers but I just found the steady glow annoying. In most cases I noted brass bases on domestic and silver bases on the Chinese product but I cannot say that is an absolute means to identify which is which.

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 Post subject: Re: Hickok Tube Testers and the SS 83 Rectifier Conversion
PostPosted: Sep Mon 13, 2021 5:03 pm 
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Joined: Jan Mon 18, 2010 2:13 am
Posts: 22714
Location: Dayton Ohio
I bought a SS 83 substitute on ebay a couple years ago and installed it in my TV-7.

I tried testing a few tubes with the original 83 and then with the SS version and saw no real difference.
Granted, I'm not sure what is inside the thing. I've seen a couple variations on the circuit.

-Steve

EDIT: I believe I got this one.
https://www.ebay.com/itm/402049984695

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Last edited by azenithnut on Sep Mon 13, 2021 11:15 pm, edited 1 time in total.

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 Post subject: Re: Hickok Tube Testers and the SS 83 Rectifier Conversion
PostPosted: Sep Mon 13, 2021 8:08 pm 
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Joined: Aug Wed 31, 2011 11:23 pm
Posts: 547
Location: Tucson, AZ
The 580 series Hickok testers have a fairly high inrush current when turned on and the power light is usually dimly lit. Some of this may also be because the transformers have some leakage as they age.

As far as the SS replacements, the initial variants did not do so well because they did not provide a fixed voltage drop, the main problem was the inability to get the set voltage correct because the plate voltages were too high. The reverse zener provides a fixed drop, I tested quite a few Hickok's when I came up with that design and there was almost no difference in the Gm test results vs. a new balanced 83 tube. I recall a there was a series of You Tube videos with the I-177 and a few others on how the initial SS replacements did not work (and were expensive) and w/zener's there was no difference in his results. I have tested TV-7's, 539, 800 series and did not see any appreciable differences in Gm. About the only difference was a slightly higher plate voltage (2-3V) with power tubes. People make such a big fuss over calibration and accuracy of these testers which I find ironic when tubes can test all over the place and still be good, and even multiple well calibrated tube Hickok tube testers of the same model have probably a 10-20% variance when testing multiple tubes. They were never meant to be laboratory standards. The 539B/C, 580 may have been a bit better, but all have some significant deficiencies and only look at one fixed operating point to fudge the Gm. The cost of the SS 83 is $1-2 in parts plus an old base. Pretty much nothing to go wrong or change over time, I guess I just do not follow why this continues to come up. If you understand the operating voltages, and they are pretty much the same, then the calibration shouldn't change.
https://antiqueradios.com/forums/viewto ... 8&t=288283


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 Post subject: Re: Hickok Tube Testers and the SS 83 Rectifier Conversion
PostPosted: Sep Mon 13, 2021 9:54 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 11114
Location: Sunbury, Ohio 43074
It keeps coming up because some people, usually but not always newcomers and/or audiophiles, want to have precision tube testers so they can sell or buy tubes matched to .00034% on Ebay to the audio crowd of course ;-) Please don't tell them that GM tube testers only test a tube at one point on its operating curve.

Also, please don't tell them that tubes, and tube testers, aren't precision devices. You'll ruin their whole day. Check it IN CIRCUIT you say? Hmph! Where's the sales profit in that!!!

I almost cry when I tell them that what they really need is a curve tracer. But egads, what will a tube tested on a curve tracer actually sound like? I bet it will sound .... curved ;-)

Ok, now with that out of the way, there is, I suppose, some possible benefit to be gained by the SS conversion in running the tester a bit cooler. I solved that one with a 1" fan running slow, and an intake port, both in the case....just to move a bit of air through it. The cooler operating may or may not extend the transformer life, but imho that's about it. With a mercury vapor tube you cannot run it too cool of course ...

So, I keep the tubes. For now, anyway. I don't run tube testers 24 hrs/day anyway :-D

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 Post subject: Re: Hickok Tube Testers and the SS 83 Rectifier Conversion
PostPosted: Sep Wed 15, 2021 3:49 am 
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Joined: Dec Sat 28, 2019 4:18 pm
Posts: 1091
Location: Corinth, TX
Barry H Bennett wrote:
I don't run tube testers 24 hrs/day anyway

True. Most of us don't.

John


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 Post subject: Re: Hickok Tube Testers and the SS 83 Rectifier Conversion
PostPosted: Sep Wed 15, 2021 5:46 am 
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Joined: Mar Sun 20, 2016 11:04 pm
Posts: 1117
Location: Mesa, AZ 85206
After having so many discussions on this, I have come to the realization that if I need an 83 tube for another application (like a jukebox amp), I will substitute a SS....I have yet to see a meaningful effect on my use of tube testers in the substitution....by my use, I mean sorting tubes for jukebox amps...hardly audiophile...

Others here have said 83s are plentiful and inexpensive....maybe in the mid west and on the east coast...not here in the southwest...

Steve


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 Post subject: Re: Hickok Tube Testers and the SS 83 Rectifier Conversion
PostPosted: Sep Thu 16, 2021 8:40 pm 
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Joined: Aug Wed 31, 2011 11:23 pm
Posts: 547
Location: Tucson, AZ
Might be plentiful if you have been collecting through the years, but most of the NOS 83 tubes on eBay/tube sellers will run you $45-100+ with shipping. Of course one should last decades, maybe. I think I have 4 or more NOS stashed away from years past, might be time to sell.


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 Post subject: Re: Hickok Tube Testers and the SS 83 Rectifier Conversion
PostPosted: Sep Thu 16, 2021 9:34 pm 
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Joined: Jun Sat 09, 2007 8:14 am
Posts: 5112
Location: Melbourne, Florida
mksj wrote:
Might be plentiful if you have been collecting through the years, but most of the NOS 83 tubes on eBay/tube sellers will run you $45-100+ with shipping. Of course one should last decades, maybe. I think I have 4 or more NOS stashed away from years past, might be time to sell.


Find A Tube $18
Radio Electric Supply $27

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 Post subject: Re: Hickok Tube Testers and the SS 83 Rectifier Conversion
PostPosted: Sep Thu 16, 2021 9:37 pm 
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Joined: Jun Fri 19, 2009 6:34 pm
Posts: 11023
Location: Long Island NY
Findatube.com has new 83s listed for $18, used tested good for $11. At that price it's not worth the time to track down and order the parts, then build a solid state replacement. As for the additional heat, I see that as a fringe benefit. Drives the moisture out of the transformers and cases.

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 Post subject: Re: Hickok Tube Testers and the SS 83 Rectifier Conversion
PostPosted: Sep Sat 18, 2021 5:46 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1530
Location: Auburn, AL
mksj wrote:
The 580 series Hickok testers have a fairly high inrush current when turned on and the power light is usually dimly lit. Some of this may also be because the transformers have some leakage as they age.

As far as the SS replacements, the initial variants did not do so well because they did not provide a fixed voltage drop, the main problem was the inability to get the set voltage correct because the plate voltages were too high. The reverse zener provides a fixed drop, I tested quite a few Hickok's when I came up with that design and there was almost no difference in the Gm test results vs. a new balanced 83 tube. I recall a there was a series of You Tube videos with the I-177 and a few others on how the initial SS replacements did not work (and were expensive) and w/zener's there was no difference in his results. I have tested TV-7's, 539, 800 series and did not see any appreciable differences in Gm. About the only difference was a slightly higher plate voltage (2-3V) with power tubes. People make such a big fuss over calibration and accuracy of these testers which I find ironic when tubes can test all over the place and still be good, and even multiple well calibrated tube Hickok tube testers of the same model have probably a 10-20% variance when testing multiple tubes. They were never meant to be laboratory standards. The 539B/C, 580 may have been a bit better, but all have some significant deficiencies and only look at one fixed operating point to fudge the Gm. The cost of the SS 83 is $1-2 in parts plus an old base. Pretty much nothing to go wrong or change over time, I guess I just do not follow why this continues to come up. If you understand the operating voltages, and they are pretty much the same, then the calibration shouldn't change.
viewtopic.php?f=8&t=288283


If you adjust the voltage during calibration of the tester, it doesn’t matter the voltage drop. Not nearly as much as most want to beleive. They didn’t use zeners when they built tube testers with solid state diodes at the factory. There are a few models from various manufacturers that used pretty much the same components and same calibration and same roll chart data with an 83 tube and then with a couple of ordinary silicon diodes. I tested power tubes and a variety of small signal tubes using solid state 83 substitute and the original 83 tube, and never saw meaningful differences with tv-7 and I-177b. The basic design of the circuit is relatively tolerant of voltage differences between the various devices. Balance between the two halves of the 83 is probably more important than a couple of volts here or there in the plate and screen circuits. The tolerances given in the calibration instructions are much bigger than one would expect from anything considered a “precision” instrument. But despite that, they’re still useful tools.

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