Raytheon Tubes

Discussion in '"Boat Anchor" & Classic Equipment' started by KF5DDW, Sep 24, 2020.

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  1. KF5DDW

    KF5DDW Ham Member QRZ Page

    I need 3 6jb6 tubes for my Drake TR-4. I found some NOS (not matched) on Ebay but read where one person had issues with Raytheons when finalizing and had to add additional capacitance. What are your thoughts on Raytheon, compared to other well known companies.
  2. WA5VGO

    WA5VGO Ham Member QRZ Page

    I’ve never found any that won’t work. Depending on the brand, it might be necessary to adjust the value of the fixed capacitor that bridges the adjustable neutralizing capacitor.
    WA1GXC likes this.
  3. WA1GXC

    WA1GXC Ham Member QRZ Page

    Theories abound. Some are plausible, but subverted by reality.

    I have 8 Drake transmitting stages, all in good order--Entire T-4X [ ] series thru late production TR-4CW.
    In a perfect world, you'd want 3 matched 6JB6 from Sylvania. Drake supplied and recommended only Sylvania manufacture.

    The reality is that in my cache of 6JB6s acquired over some years, some tubes are pristine and some are mutts- and unless
    you're a real tube afficionado, burned by a bad experience, you won't have a clue as to whose assembly line the tubes rolled-off of. I have
    Raytheon, Sylvania, RCA and GE branded tubes that were in fact produced by their arch-competitors--GE made by RCA and vice-versa, etc.
    A couple of Raytheons and a couple of imposters by GE, RCA. Re-branding was extraordinarily common between cooperating manufacturers
    for their own mutual interest--especially for TV producers' availability.

    If you have a large-enough sample of tubes, you can discern by specifics of the anode assembly, who made what. RCA, GE, etc. have very
    characteristic punch-holes and crimp tab patterns. Almost without exception, except for widely separated years of manufacture, a RCA
    plate always looks like a RCA plate. A GE always has the frosted dot matrix code pattern below the type-number on the glass. No one else
    does that. A real Raytheon (rare) plate looks like Raytheon.

    For your TR-4, you want three from the same manufacturer, for best chance of good neutralization due identical inter-electrode capacitances.
    The gentleman above is right on--you might have to modify the high-voltage trim cap across the neutralizing variable by + / - 3pf. My
    first TR-4C would not neutralize properly with the value in-place with the tubes installed.

    And a little trivia-- the 6JB6 and 6JB6A are electrically identical. Nothing to do with Internet bullsh*t about controlled heater warm-up. Both
    tubes are controlled warm-up. The RCA tube manuals do not note this, but the Sylvania tube books of 1970s specifically state the only difference
    is physical size--the "A" type has the evacuation tip in the middle of the base instead of under the plate cap, allowing the vertical height dimension
    to be slightly lower.

    Read somewhere by someone smart that tubes testing as matched fall-out of matched current characteristic shortly after being placed in service. Forget about it.

    G L
    N2EY, W1TRY, KE4OH and 1 other person like this.
  4. WA1GXC

    WA1GXC Ham Member QRZ Page

    Lowest retail price right now for 6JB6 type only -- from established and reputable N.O.S. sellers is from "Vacuum Tubes Inc."
    in Orlando. $25 new, $15 used. Owner/operator is Jim Cross--Very knowledgeable individual about
    tubes and the industry, reliable and honest merchant..

    Visit his web site for technical info about tube history. Very interesting articles. Pay careful attention to "Hall of Shame"--Tubes
    fraudulently mis-labeled.

    I have no relationship or business interest with the above seller--right now, simply, his is the best market price of which I'm aware.

  5. KF5DDW

    KF5DDW Ham Member QRZ Page

    There is a local guy selling a case full of TV service tubes (200) and said he would sell individual tubes. I've sent him two seperate requests asking if he had any of the 6jb6 tubes with no response. I guess he really doesn't want to sell. I will however give vacuum tubes Inc a a visit, thanks for the heads up.
    Also thanks to wa1gxc on the information he provided, especially about add or reduce capacitance for neutralizing the tubes.
  6. KF5DDW

    KF5DDW Ham Member QRZ Page

    After looking at that site I think I will buy used tubes at first just to see if it works as I have no history on the radio. I bought it from a silent key estate and the 3 6jb6 tubes and one other is missing. If it works I will buy new tubes and keep the others as backup. If it won't work, we'll then I have a winter project to keep me occupied.
    WA1GXC likes this.
  7. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

    Here are my preferences, as per experience, when considering sweep tubes in terms of gain, stability, and longevity:




    WA1GXC likes this.
  8. N9LCD

    N9LCD Ham Member QRZ Page

    Many major radio and television manufacturers contracted for tubes with their "brand" on the envelope so it would look "nice" when you opened the back of the set.

    I was trying to get a set of all Zenith-branded loctal tubes to give a restored TransOceanic that "original" look. That's when I found out that most of Zenith's 1**# loctals were manufactured under contract by Sylvania. I knew Zenith didn't manufacture their tubes but I didn't know who did.

    I wonder who manufactured Motorola branded TV tubes?

    Hallicrafters branded radio tubes?
  9. K1LKP

    K1LKP Platinum Subscriber Platinum Subscriber QRZ Page

  10. WA1GXC

    WA1GXC Ham Member QRZ Page

    It really depends specifically on the date of manufacture, the tube type in question, and who had production capacity. If RCA had a production run of 10,000 B & W TVs about to roll off the assembly line,
    they'd check with their tube division in Camden, NJ. (later Deptford, NJ.) for scheduling and inventory. But there were only, say, quantity 2000 6JB6. What now? They call their high-level pals at Sylvania or GE
    and purchase 10,000 to re-sell with the RCA logo on the bottle. Everyone's happy. And next year, GE will ask for the favor returned. Everyone's money is green and the TVs keep coming.

    I have a bunch of Zenith tubes made by Hitachi-Japan. (Superior quality!) Sylvania made a lot of the Loktals, but not just them. At one time, 'Loktal' was a registered trademark of Sylvania so other manufacturers
    would have to refer to them as "Lock-in Types".

    What might help you is to pull up a list off the WorldWide InterTube of
    "EIA vacuum tube manufacturer code numbers". It also appears on the website of Viva Tubes, Inc. in Easthampton Massachusetts (very honest supplier)
    There will likely be a 3-digit number on your Hallicrafters and Motorola tube bottles, maybe with a hyphen after it and additionally an EIA date code . 74-22 means week 22, 1974.
    Sometimes the data is missing. As always, a matrix of frosted dots by the type number means G.E.
    N9LCD likes this.

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