From the late 70’s to mid 80’s I was a field service tech for a local TV shop. We had contracts with three local motels for service. Quarterly we would perform a check up and tune up on all the TVs and run regular service calls as needed. All three of these motels had the infamous RCA CTC-36 sets. I never could get a decent picture out on one of these but that is another point.

On motel day I would load up one tube caddy with nothing but 6GH8As. Take off the back cover, flick the 6GH8As’, watch for arcs and sparks or symptoms to appear. I would go through typically 20-30 tubes a day. I hated motel day!

Just in general RCA used this tube for many applications in the late 60’s to early 70’s. What was wrong with this tube? The 6U8 was bullet proof but not the 6GH8.

Same here. We would change nearly all of the 6GH8 tubes in that era chassis for heater to cathode shorts. I remember it got worse when the imported 6GH8's appeared. We would order them by the hundred.
I have a McIntosh MI-3 scope with a healthy appetite for them too!

Didn't somebody here have an ad from some kind of electronic supply house that was giving special deals if you bought tubes in bulk to save, and in small print at the bottom of the ad it went something like "this offer applies to all tubes except 6GH8". Ha, they knew everyone would buy those up regardless, so no deals on those probably because GH8's were big money makers for electronic supply houses well into the 80's I bet.

I never compared the characteristics in a tube manual from a gh8 to a u8, but Im sure that would be the easiest way to uncover the major differences why the u8 was much more reliable, but then again, there could be a slight mechanical construction difference not pointed out in the manual that lead to the increased number of shorts between elements. Its always interesting to hear the people who were part of the repair scene back when these sets were still in use, many fond memories of the 6GH8...

http://justsmog.com/Clay/tum.gif

Interesting page! Shows how dramatically the console 50s B&W sets were dropping offline at the end of the 1960s...

Charles

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After I got out of the Army in 1972 I worked for a time for a parts jobber for the local TV repair shops, and we used to order those bleepin' tubes by the thousand every month. Sold every one just in time to receive the next order of Sylvania's.
I also believe that the 6U8 is a great tube, and it was used in many different types of circuits. But the 6GH8 was a money maker for the tube companies, so maybe it was engineered to be just that. :scratch2:
Kevin

6.8 million GH8's used in 1970! :yikes:

Proof positive, that was one crappy tube.

Those production lines must have really been rollin'!

Yes, drh, I have seen that "6GH8's excluded" reference. Somewhere I have a flyer from Zenith where they offered something like a free tube caddy or something, if you bought enough tubes. I suspect there was quite a bit of price competition on the GH8.

Interesting in that farther down that list AA5 radio tubes were still in there pretty strong.

Yeah, I saw 50C5 and kinda scratched my head.

A friend of mine just dropped off two AM radios from the 60s in need of new fliter cap's (hummmm)...An Admiral and a GE...both have similar tube compliments, 50C5, 35W4, 6AV6. Seems like a lot of 60's and even some 70's tabletop radios used some of the older tube types. Probably to keep costs down, and/or to use up remaining stock in warehouses.

A friend of mine just dropped off two AM radios from the 60s in need of new fliter cap's (hummmm)...An Admiral and a GE...both have similar tube compliments, 50C5, 35W4, 6AV6.
Um.. if he dropped off a radio with a 6AV6 in the string, it should be a 12AV6 (or 12AT6).
Bill(oc)

i remember subbing the 6u8 too.
some sets were really fussy and even new 6gh8 from some mfrs esp ge seemed to work poorly even when everything was right.some brand new lots often had a 20% reject rate!these things must have had critical tolerances as i saw so many with shorts.

Im surprized this box of 6GH8's went unopened. I bought this this box of 100 on ebay last year and took a picture when I was the first to break the seal. The box manufactuer has a date stamp of 5-82 on the bottom of the box so these are somewhat "new". With the RCA TV's I've picked up waiting to be serviced, probably half of this box will be gone instantly.

http://lh3.ggpht.com/_ta1B_ryr8bE/TURq3_sX9LI/AAAAAAAACAo/14CuqMvKe7c/s800/DSCF1824.JPG

http://lh5.ggpht.com/_ta1B_ryr8bE/TURq9XkHvDI/AAAAAAAACAs/AP8OFL_MJ7I/s800/DSCF1825.JPG

In the late 70's we did a lot of repairs on older color sets and we always wound up replacing all the 6GH8's in almost every set.
Towards the end )the end of me working there) the owner was ordering them by the dozen.
They were dirt cheap too, I can't remember if it was 5 for $1 or $1 each but it was cheap, of course we could buy rebuilt color CRT's for $30 back then.

Im surprized this box of 6GH8's went unopened. I bought this this box of 100 on ebay last year and took a picture when I was the first to break the seal. The box manufactuer has a date stamp of 5-82 on the bottom of the box so these are somewhat "new". With the RCA TV's I've picked up waiting to be serviced, probably half of this box will be gone instantly.

http://lh3.ggpht.com/_ta1B_ryr8bE/TURq3_sX9LI/AAAAAAAACAo/14CuqMvKe7c/s800/DSCF1824.JPG

http://lh5.ggpht.com/_ta1B_ryr8bE/TURq9XkHvDI/AAAAAAAACAs/AP8OFL_MJ7I/s800/DSCF1825.JPG

Wow, that's a lot of 6GH8's! The type number font looks like Sylvania...I wonder if RCA had quit making tubes for the most part by that time. I know the 6GH8's I've seen that were OEM in RCA sets were actually made by RCA.

Did 5GH8s have a similar problem? Seems like CTC22s and other small RCA color sets were full of them, and were fairly reliable sets.
jr

Huh, just went through my tube inventory, and yeah, from years of picking, I have amassed over 30 6GH8s, which is far and away the most plentiful of any tube I have.

Wow, that's a lot of 6GH8's! The type number font looks like Sylvania...I wonder if RCA had quit making tubes for the most part by that time. I know the 6GH8's I've seen that were OEM in RCA sets were actually made by RCA.

You're correct Chad, these are sylvania made tube as the script has the "USA" under the letter, which easiliy identifies the manufacturer as sylvania. Real RCA made tubes would have had the octagon around the tube number. Not sure when they pulled the plug on tube production though. Seems like more lost history in the electronics industry.

I wonder when consumer grade (radio. TV, phonograph, etc.) tube production ended in the USA? In the mid '90's, I remember buying some USA built PhilipsECG tubes for use in TV's; but, they could have been sitting on the dealer's shelf for years. About a year ago, the old man who owned the local parts house said he still had a ton of new 6GH8A's and wanted to know how many I needed. I didn't say much, as he's one that is a little proud of his stuff. He has since passed away and I think his son is running the business. Now might be a good time to see if those tubes are still around.

I know that some of the last tubes produced in the GE factory in Owensboro, KY. were 6550's I think in around 1992-1994 or so. The company which owns the factory now is called MPD, Inc. making microwave devices but they continued to make glass tubes up until that point. I'm not sure if they made other tubes in the 90's or just the 6550. I worked on a Leslie organ amplifier which was newly made in 1992 and used the MPD 6550 tubes.

They had the "Electronic Tube" script logo just like GE but no GE monogram and the date code was 92. They said something like "Made to GE specs by MPD inc. in Owensboro, KY."

I have seen some PhilipsECG tubes too which likely were from the late 80's, a 6HA5. They said SylvaniaECG with the modern Sylvania logo on the tube for a while and then the very last ones said PhilipsECG but I think they were made in USA in the original Sylvania factory.

Did 5GH8s have a similar problem? Seems like CTC22s and other small RCA color sets were full of them, and were fairly reliable sets.
jr

I had one of the early model CTC22's. It had a great picture on it. I think I replaced the 5GH8's twice in the three years I owned it.

the 5gh8 was just as bad.i remember replacing every last one in some sets just like with the 6gh8.

Hmm I'll chime in here - here's what I've always heard quoted from years of reading about tube audio.

RCA - 1976 stopped making consumer tubes, but kept making certain transmitter and industrial tubes until the early 80s. I have some genuine RCA 807s from 1982.

Sylvania/PhilipsECG - 1988 stopped making tubes. Sylvania made tons of tubes for the US government though the 80s, as well as audio power tubes until things shut down. In the early 90s I bought a number of PhilipsECG audio tubes which were either Chinese or Russian, with early 90s date codes, so the name didn't die with the factory. Don't know when it did.

GE - As above, up till 1992 the GE factory was making at least the 6550. I remember ads in the back of Popular Electronics in the early 90s with bulk quantity pricing on about 10 GE tube types, so it must have been more than just the 6550 until almost the end.

Westinghouse - not sure... but I was buying Westinghouse branded tubes new until the early 90s - all were imports and not really made by Westinghouse

This isn't lost history, there's books written on the subject and it's well documented due to the strong interest in tubes from the audio and antique radio communities. I always enjoy reading about the history of the electronics industry in North America.

To connect this back to the original thread, the only device which I have which uses 6GH8's, is my 1990 Dynaco ST-70 reissue. Dynaco explained they used it because the original's 7199 was too expensive by that point. I've been using it for several years without changing the tubes, but I did have to test a whole pile of used ones before I could find a pair which tested good.

Anybody have a copy of the Application Note for the 6GH8? RCA promoted the 6GH8 to everybody, and the application note (24 pages, according to my Radiotron Designers Manual) probably had a sampling of RCA-designed circuits for use with the 6GH8's - Audio, Video, Chroma, Pulse, you name it. It's the broad application (and RCA's insistance that it be used in every RCA TV) that brought it into the limelight. 6EA8, 6U8, 6BL8, 6KT8 - everybody used some form of the triode-pentode in their sets.

When I was a kid in my Dad's TV shop., I would be amazed when he would fix a set with a 6GH8 problem, by merely swapping the 6GH8 out with another 6GH8 in the set, never having to replace anything. Not working as a Chroma Oscillator? No problem - swap it with the Bandpass Amp tube (another 6GH8) and watch the magic. You could throw a hundred 6GH8's in a circuit and find that only half would work, but all would test fine on any Hickok, Sencore or B&K tube tester out there. I'm sure it boils down to different electrical characteristics that are never tested - stuff like plate capcitance, inter-electrode capacitance, and the like.

It would be interesting to contrast the 6GH8 with "the most used transistor of 1980 - would it be a 2SC1172B, a 2SC945, or some other Japanese wunderkind? :sigh:

Cheers,

20 years ago I met an old, retiring TV repairman. (He had been an Admiral dealer, and was quite a character) Among other things, he sold me a couple caddies full of tubes. Dozens of 6GH8s, and man, did I think I'd got a great deal! But every one of them was used.

Among my current stash of NOS GH8s I try to keep a variety of brands, figuring if one doesn't work another might be closer to what the set wants. I think I have some Hewlett-Packard branded tubes, which are probably RCA or some such, but I figured maybe they demanded the better grades?

I picked up some NOS realistic brand (rat shack) 6GH8's at a ham fest for VERY cheap (IIRC guy just gave em to me), anyway very nice looking tubes, gold pins, but I seem to recall them not working well when I tried them in some of my sets.

I have a huge collection of 65- 72 color sets and hardly ever have problems with 6GH8s. I will say that whenever one is change in the color circuit its a good idea to do a color afc alignment. The tolerance of those tubes is all over the place.

I was 14 in 1970 and knew little to nothing about TV repair. My friend and I used to ride our bicycles back behind TV repair shops and dig through the dumpsters. Over a short period of time I amassed quite a large collection of 6GH8's. They always seemed to test ok in the testers at the drug stores.

I wonder when consumer grade (radio. TV, phonograph, etc.) tube production ended in the USA?

Heard an urban legend to the effect that GE and RCA independently hired the same consultant and asked him if it still made business sense to keep making tubes and tube consumer equipment. He said no to both (neither knew that he was reporting to the other company), and both companies bailed out.

I thought I understood that RCA called it quits on tubes in 1977.