Viewing 15 posts - 1 through 15 (of 26 total)
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  • #5300
    Eric Strasen
    Forum Participant

    Just who is responsible for those spray-shield tubes we have cursed from time to time? Was it Rogers in Canada or Grigsby-Grunow in the U.S.? They both made them, and I’m not aware that anyone else did.
    I’ll provide a little GG history. Maybe someone else can chime in for Rogers.
    The Grigsby-Grunow-Hinds company began business in Chicago in 1921, initially making electrical parts for the auto industry. In the mid-1920’s, they began marketing battery eliminators for battery radio sets. Sometime later, they also started making horn speakers. Both were branded “Majestic.”
    The speakers were quite good looking and sounding, but the horns were made of celluloid and very few have survived into the present.
    As demand for battery eliminators nosedived following the switch to AC radios, Grigsby-Grunow (Hinds had departed) decided to enter the radio business and their first sets went on sale in 1928.
    Sometime around April, 1929, they began manufacturing their own tubes, again under the Majestic brand name. Later that year, they bought the failing LaSalle tube making operation — probably because LaSalle had an RCA license to produce tubes and GG didn’t.
    I am a bit cloudy as to when GG started spray-shielding some of their tubes. They were quite proud of these, which were mentioned prominently in their radio advertising. A study of their ads from 1929-1933 could come close to pinpointing a date.
    GG’s shielded tubes differed from Rogers in several aspects. The GG tube shielding did not cover the bakelite base — a ground connection was made internally through the appropriate pin.
    Also, the tops of the tubes were left bare — especially those having grid caps, to prevent accidental grounding I presume.
    GG shielded only currently existing tube types and had easily understood labeling. A standard 58 made by GG was labeled G-58. A shielded 58 was a G-58-S. Rogers created some tubes of their own design, not interchangeable with anything else, and also spray shielded existing tube designs but gave them truly weird designations. Thus, a 6K6G became a shielded 41M and a 6A8G became a 6A7M.
    Finally, about the time octal tubes hit the market Grigsby-Grunow was in bankruptcy. They never made an octal tube.
    The Rogers tubes I have seen (not all that many) were octals.
    I’m guessing Grigsby-Grunow was first, but you be the judge.
    Eric S.

    #5371
    Bob Masse
    Forum Participant

    Rogers had a relationship with Grigsby-Grunow and in 1928 Rogers-Majestic was formed.
    https://www.hammondmuseumofradio.org/rogers.html
    Here is a time line and some info.
    https://www.broadcasting-history.ca/index3.html?url=http%3A//www.broadcasting-history.ca/station_groups/Radio_Television_Station_Groups-Standard_Broadcasting.html
    This article says Rogers was first with the spray shielded tubes. No reference as to where the info was obtained, though.
    https://www.ieee.ca/millennium/alternating_current/ac_halloffame.html
    Here is info on the relationship between Rogers , Kellogg and Mcullough in tube development. Scroll both ways to read story.
    https://books.google.ca/books?id=QNJGAFkdY40C&pg=PA79&lpg=PA79&dq=mccullough+tubes&source=bl&ots=g5t8JrkSLn&sig=2wEFydqQDaoBCUbhXdua4NNDmWs&h

    I can’t find the patent on the spray shielded tube. But from my research I would say that all parties involved worked together, for these accomplishments to take place.
    Bob

    #5372
    Eric Strasen
    Forum Participant

    Bob,
    Thanks for the information! I had no idea Rogers was so heavily involved in radio and tube development, not to mention broadcasting.They even had an experimental FM station (VE9AK) prior to WWII.
    Did Rogers make any spray-shield tubes in the pre-octal base configuration, which would have been before 1935?
    If they did, then I’m sure they invented the process and Grigsby-Grunow just went along for the ride.
    GG was not noted for innovation in the tube making business. In their own plant and the LaSalle facility they later bought, they mostly manufactured tubes designed by others.
    I’m pretty sure the “merger” between Rogers and Grigsby-Grunow, mentioned in a couple articles you cited, was not much more than a cross-licensing agreement, as Rogers did not go down the tubes when GG did in 1933-34.
    One of my U.S. sources — I think it was Antique Radio Classified in a history of Majestic radios — said Rogers made two separate lines of radios in the late 1920’s — one under the Rogers name and one under Majestic (NOT Rogers Majestic). The author said the main difference between the two lines was cabinet design. The innards of both supposedly were Grigsby-Grunow. This sounds unlikely to me.
    Eric S.

    #5380
    Eric Strasen
    Forum Participant

    For anyone interested in radio history — specifically Grigsby-Grunow history — this is a very good article by Paul Turney at https://www.antiqueradio.com/SepOct10_Turney_Grigsby-Grunow_Part1.html.
    It’s the first of a two part series and covers the company history from inception to impending bankruptcy.
    Unfortunately, he does not cover the GG relationship with Rogers, nor does he mention GG’s purchase of the Columbia Phonograph and Record Co. (yes, THAT Columbia) during the firm’s almost manic expansion during the late 1920’s and early 1930’s. It was this spending binge which most likely killed GG.
    Eric S.

    #5381
    Bob Masse
    Forum Participant

    Here is a link to a Rogers 89RS spray shielded tube.
    https://www.radiomuseum.org/tubes/tube_89rs.html

    Here are pictures of my Rogers 6G7S tube which was the direct substitute for the 89rs. Also there are pics of service manual notes for the Rogers R-371 radio chassis. The 6G7S tube was used in production as of Oct, 1, 1934. It is a 7 pin pre-octal tube.
    Bob

    Additional info: Rogers got a US patent for a machine used to spray shield tubes. Here is the link.
    https://www.google.com/patents/US1981149

    • This reply was modified 1 month ago by Bob Masse.
    #5396
    Eric Strasen
    Forum Participant

    Bob,
    A three tube radio, with one tube serving as a half-wave rectifier AND power output tube?? WOW! Or am I reading the schematic wrong? Is there a second chassis somewhere?
    With the original patent dating back to 1932, Rogers undoubtedly gets credit for the spray-shield tube.
    Plus, my electronics engineer friend in Georgia tells me that he serviced some U.S.-made laboratory electronics which used Rogers spray-shield tubes, back in the day.
    In my internet meanderings this a.m., I ran across the second part of the Grigsby-Grunow history, detailing their plunge into bankruptcy.
    It also gets into their cat fight with Lt. Cmdr. McDonald of Zenith (apparently, this was before he had himself promoted to full commander, so as not to be outdone by General Sarnoff of RCA).
    Here’s a link to Part 2 of the GG story. It’s a lot shorter than Part 1.
    https://www.antiqueradio.com/SepOct10_Turney_Grigsby-Grunow_Part2.html.
    And here is a blurry shot of my Majestic G-58-S spray-shield tube. It’s N.O.S., but worthless. The most microphonic tube I’ve ever run across. A gentle breeze will set it all a twitter.
    Eric S.

    • This reply was modified 1 month ago by Eric Strasen.
    #5400
    dwhite
    Keymaster

    Hi Eric/Everyone:

    The links you posted to the GG articles are great and they reminded me we haven’t yet created a page on the website where links to information/articles like this can be posted. So, I am going to get that going asap, and then post all such links as members provide, starting with your two GG articles, Eric. Also, as an interim measure, I am going to post these two in Forum Lounges\General Interest\Of Interest (a topic I started a while ago and which already contains an article on Tesla). If anyone has any links to online articles that might be of interest to vintage radio/electronic aficionados, please post them in that topic, and I will duplicate the links on the webpage as soon as we can get it operational.

    Thanks everyone!

    Don

    #5401
    dwhite
    Keymaster

    I just saw all the links you posted, Bob, so I’ll go through those as well!
    Don

    #5403
    Eric Strasen
    Forum Participant

    The patent info/description Bob provided is worth a look-see.
    Rogers invented machinery for sand-blasting the tubes prior to the coating process. I always wondered how they got the paint to stick to glass, and now I know.
    Grigsby-Grunow’s spray shielding must have been pretty primitive compared with Rogers. Some of my GG Majestic shielded tubes are losing large chunks of the coating.
    Eric S.

    #5408
    Bob Masse
    Forum Participant

    Eric,
    You read the schematic correctly. It is all on one chassis. Here are some pics.

    #5420
    Eric Strasen
    Forum Participant

    Bob,
    Thanks for the pictures.
    About the same time, Grigsby-Grunow was advertising their “duo-valve” spray-shield “Smart Sets”, stating their six tubes were the equivalent of eight.
    No tuned RF stage, however.
    Their Majestics looked great, but were mediocre performers.
    Eric S.

    #5421
    Bob Masse
    Forum Participant

    Yes I find those old Majestics quite artistic. I have never seen one in Canada though. If am radio ever goes out, those very artistic radios would still be very collectible, just to look at.Thanks for all the links and pics.
    Bob

    #5423
    Eric Strasen
    Forum Participant

    Bob,
    Shortly before they affiliated with Rogers, Grigsby-Grunow was talking about opening plants in Europe and Canada, based on their outstanding sales success in the U.S.
    They outsold every other U.S. radio manufacturer in 1929.
    I wouldn’t be surprised if their agreement (or whatever it was) with Rogers was a promise to stay out of Canada.
    All the Majestic “Smart Sets” of 1932-1934, consoles and table radios, used the same basic, mediocre, chassis.
    The consoles had larger speakers, of course, but there wasn’t much in the way of audio circuitry driving them.
    But God, were they good to look at!
    Here in the U.S., you can buy low-power a.m. transmitters and play CD’s and whatnot through your radios. The FCC doesn’t complain unless you go hog-wild with an antenna for the transmitter.
    I have a transmitter kit which I may wire-up sooner than later, as a.m. programming here is wretched.
    Attached is a photo of a 1933 Majestic “Park Avenue” console
    Eric S.

    Attachments:
    #5425
    Bob Masse
    Forum Participant

    Beautiful radio. I’m always impressed with the artistic designs, of just about everything, from the 1920’s through the 1940’s.

    I haven’t tried this yet but, it is possible to make reproduction spray shield tubes. Take a look at all the products here.
    https://www.mgchemicals.com/products/protective-coatings/emi-rfi-shielding/total-ground-carbon-conductive-coating-838/
    I’m thinking a person could air brush, using compatible paint, to the correct color, after applying the coating. It might be worth a try with the really rare tubes.
    Bob

    #5426
    Eric Strasen
    Forum Participant

    Bob,
    This sounds like a viable proposition.
    One would not have to have access to a sand blaster to prep the tube glass, either. I have a small plastic bottle of some fluid I occasionally use to “frost” pilot light bulbs. Not sure what it is (dilute hydrofluoric acid?).
    I certainly can see using this process to convert a 6A8G to a 6A7M for my Rogers Majestic table radio.
    On the subject of good looking cabinets, I’d like to recommend a site devoted to Midwest radios. Lots of interesting cabinetry here, and Mike Simpson appears to have devoted his life to collecting as many Midwests as he can find.
    I corresponded with him when I scored my 1937 Midwest 16 tube console on eBay, and learned he had done the electronic restoration on the chassis! The seller had refinished the cabinet beautifully. This radio is the centerpiece of my own collection.
    https://www.midwestradiomuseum.com.
    Eric S.

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