Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Jul Tue 23, 2019 10:09 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 40 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: 83 Rectifier
PostPosted: Jul Mon 04, 2011 4:44 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 3270
Location: Seattle WA US
I've just encountered my first type 83 mercury vapor rectifier. One question: there are a bunch of gray flakes rattling around inside the envelope. Is this usual, or acceptable, in one of these tubes - or should I just discard it without giving it a chance to damage either the power supply that its a part of, or my tube tester ?

<edit... on closer inspection, the gray flakes seem to have peeled off of the plates !!>

Thanks,
Chuck K7MCG


Last edited by K7MCG on Jul Mon 04, 2011 5:58 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Mon 04, 2011 8:54 am 
Member

Joined: Apr Tue 19, 2011 6:24 am
Posts: 455
Location: Wayne, NJ 07470
Chuck,

Perhaps your 83 was shaken in storage or transport over the years. Mercury vapor tubes often wind up with splattered mercury in all the wong places, and it needs to be vaporized and recondensed to the bottom of the tube prior to application of any high voltage. If not, you may get catastrophic arc-overs or shorts, etc.

Your tube might still be good if the flakes you noted are condensed mercury that settled on the plates. Very often such debris is grayish and irregular and looks dirty. It may be anywhere within the envelope or on the elements. If the flakes are whitish and of generally regular width (~1/16th inch or so), , they may be particles that flaked from the filament ribbons. Those would be pieces of the emissive coating needed to provide proper operation. ( Just a few small ones may not cause harm in your application, but you won't know until you test the tube for proper emission.)

However, don't do that right away.

Best way to resolve the matter may be to put the tube in a tester and light the filament at 5.0 V. Don't apply any other voltages ( i.e., DON'T press any test /merit buttons, etc.) All you should do is heat the filament at the rated voltage.

While the filament is first warming up if you are fast enough, you may or may not be able to observe the color of each ribbon by lookng from above, and down inside the plates. If the coating is flaked off in spots, you may be able to observe a slight difference in the regions where it is gone, but that is sometimes tricky. (To slow it down a bit, you can set Ef at 3.3 volts or whatever your tester can provide without harm , and you might be better able to visualize it, because at 5 .0V, the filamentary ribbons heat quickly to a dull orange, around 800C or so. - At lower temperatures, the mottled appearance of damaged areas is easier to observe. Just don't go to 6.3volts as you won't gain anything and may burn the tube out if it is already old and tired...)

Regardless, the next step is to heat the tube at 5.0V, not more. Don't tap the tube; this process is thermal and will either work well or not remove the crud you described.

Allow at least 30 minutes for the tube to get good and hot, as that should be sufficient to vaporize and redistribute any loose mercury in the bottle, regardless of whether it is on the glass or on metal parts. If you want to really heat the tube up, you can wrap it in tinfoil, and let it bake for a while. It will be dissipating 15 watts, and will get hot enough to burn you. if you have a small tin can ( soup can without the label ) that will suffice. Be sure to keep the tinfoil away from the base.

After that time, turn the tester OFF and let the tube cool in its socket until it is at room temperature.. DO NOT unseat it. Remove the tinfoil or can if you used it.

Visually examine the tube under bright light. Look for the gray crud that you fist encountered. If you are fortunate, it will be gone, and you will find bright mercury droplets around the bottom of the tube, below the stem press. You may even find a tiny puddle of fresh looking mercury, depending on the maker and the age of the tube. If there is still some crud in the bottom of the tube, go ahead and test it, but be cautious; likely it will work properly if the tube passes the shorts tests.

If all looks good, then turn on the tester, let the tube heat for at least 3 minutes, and test away normally. Mercury vapor rectifiers should be allowed to pre-heat, so that there is sufficient vapor pressure inside to assure proper ionization.

THERE SHOULD BE A NICE BLUE GLOW INSIDE THE PLATE STRUCTURES UNDER NORMAL OPERATION WITH B+ APPLIED.

That is the visible emission from the ionized mercury. Be cautious, as there is plenty of UV radiation as well; the glass doesn't block it all, and you can hurt your eyes by staring at unfiltered mercury emissions. Sunglasses should help, if you want to make a hobby of looking at mercury rectifiers for any real length of time, especially big ones such as are used in transmitters, etc. ( e.g. 866s, 872s, 575s, etc.)

If the tube tests good, then carefully remove it from the tester and keeping it upright ( don't slosh the mercury around) , install it in your set and have fun.

If you are servicing the set, you may need to turn it upside down to work on it. That makes Mr. 83 unhappy, and so you might want to use an 83-V ( vacuum version, no mercury) forthat inverted application ( an 83-V is an earlier version of the 5VG - you can make an adapter a/r Both the 83-V and 5V4 have heater cathodes and draw only 2 amps vs. 3 amps of the old 83 mercury tube. Note the 83-V's cathode is connected to pin 4...) Using a 5Z3 as a substitute won't be quite right as it has a far greater internal voltage drop than does the 83/83-V), and the lower B+ DC might not help in your troubleshooting. Think about what you are looking for and use the appropriate rectifier during testing. The 5Z3 will be a bit easier on the filter capacitors, but the resultant lower DC voltages may screw things up a batch.) As always, bring it up witha Variac.

Since your radio came equipped with an 83, that's what it needs to be faithfully restored. Of course, an 83-V will cut your power xfmr a 5 watt reduction in load ( 2A vs. 3 A). Only you know what you'll want to do. Have fun!


John


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Mon 04, 2011 9:54 pm 
Member

Joined: Nov Sat 27, 2010 6:15 pm
Posts: 5449
Most all Hickok tube testers have 83 rectifiers, and they all have them mounted horizontally whereas the tube manufacturers all specified they be mounted vertially, and certainly not upside down. Now how these damn things rattled around in trucks, got lugged around and whatever, and still worked is beyond me. When I got my 533 it looked like it had been to hell and back. I have a spare 83 and 5Y3 (uses both,) but have not had to replace either of them in tha last decade.

So, it is normal to see splatters of silver colored mercury around the bulb, especially if it has been shipped somewhere. Gravity will prevail and the mercury will eventually settle towards the bottom of the tube, so keep it upright. You could tap it a few times lightly, say with a chopstick, and that will speed things up a little.

Now, no guarantee. If the vacuum has been breached in less than an obvious trauma, you may not know. If I was suspicious, would probably hook up a 5 volt transformer to a tube socket and see how it warms up. Nice normal glow, OK, otherwise NFG. If good, I would proceed to the tube tester.

If you do have to replace this, please dispose of the dud responsibly. I think we have a simultaneoous responses in progress, so I will send what I have now.


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Mon 04, 2011 10:17 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 30698
Location: Pocasset, Cape Cod, MA
Hickok got away with horizontal operation because there is no plate voltage applied until the test button is pushed. So the tube has time to warm up.


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Mon 04, 2011 10:31 pm 
Member

Joined: Nov Sat 27, 2010 6:15 pm
Posts: 5449
I see your barbeque isn't ready either. So on a cold start would there be a duel between the 83's if the 'test' button was pushed? I really don't want to do this, but, you are the master.


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Tue 05, 2011 10:55 pm 
Member

Joined: Jun Tue 02, 2009 3:38 am
Posts: 1271
Location: Albuquerque, NM
Here is a pair of 816s rectifying away for a 6V6 mono amp I've got to give you an idea of what color to look for.

Image

The back one has flakes off the anode like it sounds you're speaking of. I haven't had any issues running it yet... hopefully I'm not speaking up too soon here! lol but I did put a 1/4 amp fuse in series with the anodes so if it does short one day it'll take the fuse instead of my transformer. It's almost like they coated the anode with a silver paint and it just hasn't done well through use.

_________________
-Kyle


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Tue 05, 2011 11:09 pm 
Member

Joined: Aug Tue 24, 2010 8:56 pm
Posts: 5653
Location: Northeast Florida
A mercury vapor rectifier in a tube tester?

Why?

_________________
William


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Tue 05, 2011 11:17 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 13817
Location: S. Dartmouth MA 02748-1225 USA
tubes4life wrote:
A mercury vapor rectifier in a tube tester?

Why?

Low voltage drop, higher current capability, series regulation...

_________________
Smith's Ale Gives Strength, Smith Bros. Brewers, New Bedford MA


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Wed 06, 2011 12:02 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 12549
Location: Mpls, Minnesota
Many of these 83's have the flakes you are talking about and they work fine.

Dave


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Wed 06, 2011 12:21 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 30698
Location: Pocasset, Cape Cod, MA
Specifically, a constant voltage drop (13V) for any current. You can compensate for that in the calibration. If the drop varied, you couldn't; power tubes would always read low.

An 83 has a pretty easy life in a tube tester. Anode voltage is only 150V. Even if you pushed the Gm button immediately, the tube under test won't have warmed up, so there's no plate current.

If it weren't for Hickok, the 83 would have been history by 1934, just like the 82.


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Wed 06, 2011 12:35 am 
Member

Joined: Aug Tue 24, 2010 8:56 pm
Posts: 5653
Location: Northeast Florida
Ok, thanks.

_________________
William


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Wed 06, 2011 7:59 am 
Member

Joined: Apr Tue 19, 2011 6:24 am
Posts: 455
Location: Wayne, NJ 07470
All the above are really good inputs. Chuck asked what he ought do with a dirty 83 tube in uncertain condition and didn't describe his application; the info I provided might be considered overly thorough and conservative by many in ARF. Potential risk to antique power transformers drove my reply. Besides, conditioning mercury vapor tubes can be fun, though commonsense might get some 83-Vs substituted instead.

In general, I somewhat begrudge the use of small mercury-vapor tubes such as KR-1, 1, 82, 83, etc. and only use them in the interest of accurate restoration when appropriate. The potential health hazards, RFI/hash, and possibility of arc-backs and transformer damage are concerns of little consequence to the original designers who used M-V tubes. By the mid-1930s those less exciting, non-mercury replacements, such as 1-Vs and 83-Vs came about for good reason. Still, M-V tubes can be things of beauty and wonder…


K7MCG’s major concern was unidentified crud inside his tube, which could potentially cause a short or an arc-back ( PIV is jeopardized by reduced F to P spacing if there iscrud inside the plate). Cooking ("conditioning") an M-V rectifier to vaporize and re-condense mercury after rough handling or prolonged storage is good practice, and was nicely discussed in RCA's small transmitting tube manuals. A friend, a tube engineer at RCA’s Harrison plant, explained it to me over five decades ago. He was pretty adamant about getting the mercury down where it belonged and showed me how to do it and also pointed it out in RCA's manuals.


What K7MCG's own set needs remains unknown here. If it’s a big set or an audio amp, he might condition that M-V tube in the interest of safety, or try an 83-V / 5V4 instead. Smoke-testing a big old transformer may not be the goal.

I'm familiar with Hickok's sideways mounting of 83s, have one here and always disliked that design feature. Regardless of the unstressed application, I've always wondered at how they got away with it, and what failure modes and effects analyses they did, if any. As Alan Douglas points out, Hickok’s application was relatively safe; that’s due to their undemanding, momentary conditions of use unlikely to be encountered elsewhere.
Perhaps Mr. Douglas might comment on service problems ascribed to the sideways 83s in Hickok testers.


Codefox’s suggestion of bopping the tube with a chopstick may or may not work. I’ve had M-V tubes with misplaced mercury crud virtually welded to the mounts, and only prolonged heating got rid of it.
Tapping the tube may encourage the alkalai coating materials to separate and flake from the filament ribbons and harm a marginal tube.

His good comment re responsible disposal of M-V rectifiers is especially welcome. Some towns take CFLs and other fluorescent lamps for recycling, and it might be possible to get rid of M-V tubes that way. Alternately, treating them as HAZMAT waste poses larger problems in some jurisdictions. Perhaps sending them (anonymously) to one persnicketty town near Rochester, NY might be a solution.


Tube manuals, such as the 1943 Sylvania Radio Tube Technical Manual, RCA's several Receiving Tube Manuals detailing the 83 for new design (e.g. RC-11 through RC-16, maybe later.), and RCA's later Transmitting Tubes Technical Manuals (e.g. TT-5, etc.) all specify that type 83 be installed with the base DOWN.

Interestingly, the venerable 83 is one of the very few tube types to be consistently specified in detail in Receiving Tube and in Transmitting Tube manuals through the 1940s. It filled a niche and must have been a money-maker.

Here’s an excerpt from RCA's 1962 TT-5 manual, page 71:

Mercury-Vapor Rectifiers
A mercury-vapor rectifier tube must be handled with special care to prevent dispersion of the liquid mercury from its normal position at the bottom of the bulb. Spattering of the mercury over other portions of the bulb or on the anode or on the filament must be avoided because it may lead to internal shorts or arc when the tube is placed in operation. A mercury-vapor tube should always be transported, stored, and operated in a vertical position with the filament end down, and should never be rocked or allowed to snap into place in its socket or mounting, and should be protected against excessive equipment vibration.

If spattering occurs, the dispersed mercury must be reconcentrated before the tubes are placed in service by means of special preheating and conditioning treatments. …”

( Following that, RCA provides instructions for conditioning including gradually increasing applied B+ voltage to the previously-cooked M-V tube(s). I suspect that their professional thinking was likely aimed at rectifiers far larger than the humble 83. Still…


Chuck, please let us know how it went, how good a tan you got if you ventured to play with your 83, or if you used something else in your target set.

73,
John





ps - OK, I admit to sometimes removing the silicon and reinstalling 872As back into an old 2500V supply and lighting them off as a reminder of high-school days when the earth was still cooling. It was nice to watch the modulation of their arcs by the load current. All my 866 sockets werefilled by 3B24s or 3B28s decades ago., and the few survivors left here now have very boring and much safer solid-state devices. /j


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Wed 06, 2011 6:21 pm 
Member

Joined: Nov Sat 27, 2010 6:15 pm
Posts: 5449
Wow, great information. I suppose that the rectal mercury thermomoter broke whilst measuring my thermal condition as a tot, which explains my fondness for Danbury, CT.

But just to repeat, there's nothing funny about mercury switches (like in ancient thermostats,) very old batteries from hearing aids, cameras, etc..., and of course mercury vapor tubes. The s**T doesn't die.

Let's do our part for the kids.


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Thu 07, 2011 12:01 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 3270
Location: Seattle WA US
Updating.... I gave the 83 a good long bake with a foil jacket, then tested it. One side tests OK, the other side tests weak, with the blue glow inside the plate flickering a bit. No apparent change in the loose junk inside the envelope.

This 83 was used in a heavy, high quality regulated power supply, with all Peerless transformers, and 3 6AR6 series regulator tubes. Power transformer 800vct @200madc. Good boatanchor. The 83 was apparently chosen for its low voltage drop - as the active regulator following would make the good regulation properties of the 83 unneeded. I'll look for an 83V for use while recapping and checking out the supply, and go back to an 83 if I find I need more output voltage than the supply can deliver with the vacuum rectifier.

Thanks for all the info & advice.

Chuck K7MCG

<edit: I just realized that the low, stable forward voltage drop of the 83 is a lot like that of a pair of 1N4007 plus a 12 volt 5Watt zener......tubelovers please forgive my language.>


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Fri 08, 2011 6:39 am 
Member

Joined: Apr Tue 19, 2011 6:24 am
Posts: 455
Location: Wayne, NJ 07470
<edit: I just realized that the low, stable forward voltage drop of the 83 is a lot like that of a pair of 1N4007 plus a 12 volt 5Watt zener......tubelovers please forgive my language.>


Great comment! Absolutely so. About fifteen years ago I built such a substitute "83" using two 1N4006s per AC leg and a 1N2811A in series with the rectified DC. That added up to ~15.2volts of Vf equivalent drop, as each 1N4006 has ~1.1Vf drop or so, rather than the usual 600mv . The ancient 1N2811A is a 13V +5% 50 watt Zener in a TO-3 case. I have some doubts that most 5W Zeners can handle the peak currents involved, and may later re-run the numbers for thiis ARF topic if time permits.
(If I recollect, Ifmax into a 20uF cap was well over an amp peak, as I measured it with a Tek current probe, but after fifteen years and the loss of my notes....)

The thing worked fine, but of course, there was NO rectifier warmup time. ARF readers attempting something similar may need that protect other tubes that may be in the same equipment. As this was for a homebrew hamfest B+ only supply, it didn't matter. I never did use an Amperite 30 second time-delay relay as originally planned to hold off B+, having acquired some decent Kepco HB series adjustable lab supplies, and gave the old unit away. I should have kept the "SS-83" for my tube tester, duuuhhh. Maybe I'll build a newer version someday.

Why the monster Zener? To reliably tolerate the substantial inrush current of the input filter capacitor; also I had some 1N2811A's at hand. I'd put it on an aluminum plate that mounted via ceramic standoffs to a 4 prong male Amphenol saddle mount plug , and covered the device with a plastic TO-3 cover that I'd spray- painted red.


Even then I didn't love 83s...


John


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Sat 09, 2011 3:31 am 
Member

Joined: Nov Sat 27, 2010 6:15 pm
Posts: 5449
After all is said and done, a fw rectifier that is weak on one side puts a real strain on the transformer, and is a time bomb at best

I think most of us could design a regulated solid state replacement for under 3 bucks.

But that is boring.


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Sat 09, 2011 8:26 am 
Member

Joined: Oct Sun 11, 2009 10:06 am
Posts: 1441
Location: British Columbia
easyrider8 wrote:
Many of these 83's have the flakes you are talking about and they work fine.

Dave


Yep. 866 rectifiers have the same sort of thing happen. The material on the plate structure flakes off and lands in the base (and sticks to the sides) of the bulb. No problems.


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Sat 09, 2011 2:14 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 30698
Location: Pocasset, Cape Cod, MA
The 13V forward drop of an 83 is a bug, not a feature, and there's no reason to emulate it.


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Sat 09, 2011 4:33 pm 
Member

Joined: Apr Fri 23, 2010 4:02 am
Posts: 1444
Why do the plates flake off?

Is it a reaction to the Hg or is it the type of material??


Top
 Profile  
 
 Post subject: Re: 83 Rectifier
PostPosted: Jul Sat 09, 2011 11:03 pm 
Member

Joined: May Sat 14, 2011 5:42 am
Posts: 3497
Location: Ft Worth TX
I couldn't withhold the nostalgia. I used to watch MV rectifiers rock N roll to the music in a Gates 5kW transmitter at KBOX in Dallas.

Some enterprising soul invented and sold SS socket-substitutes for MVs in 1950s RCA television transmitters. No fun to watch though.

_________________
Tuyo is Spanish for 'your'; why isn't yoyo Spanish for 'mine'?
Escuchen Tube = bilingual malapropism


Top
 Profile  
 
Post New Topic Post Reply  [ 40 posts ]  Go to page 1, 2  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 3 guests



Search for:
Jump to:  


























Privacy Policy :: Powered by phpBB