4D32 rig is back!

Discussion in 'Amplitude Modulation' started by N2DTS, Sep 2, 2016.

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  1. K5UJ

    K5UJ Ham Member QRZ Page

    Pure speculation: Commercial manufacturers could get the 6146 easily and cheaply and it required an octal socket instead of the more expensive porcelain socket for the 4D32, and then as now, manufacturers liked saving production costs.

    Home builders probably thought like this: If I'm going to build a rig, I may as well build with a couple of 813s or something else like a 250TH and aim high with 2 KV or more. While the size of the 6146 and 4D32 are appealing for mass production due to the economy of a smaller cabinet and savings resulting from < 1 KV plate v., a ham building only one, may not feel like he has to limit himself that way.


  2. N2DTS

    N2DTS Ham Member QRZ Page

    Must have been price, or maybe it was not stocked like RCA tubes were.
    I think RCA designed the 6146, but then many other companies started making them.
    How does that work, did they have to pay RCA for the rights?

    Many rigs used a pair of 6146's, only a few very early rigs used the 4D32.
    I suppose the 6146 by itself works better at higher frequencies, but when you put two in parallel, I suppose it negates any advantage.
    Maybe the military bought them all up...

    I am not sure where the ratings came from, since you can plate modulate them at 1200 to 1400 volts on the plate without problems, but they are only rated for 600 volts in plate modulation.
    They make a nice match for 811's at 1000 to 1200 volts.
    Maybe I should build up a quad RF deck, 400 watts carrier easy.
  3. N2EY

    N2EY XML Subscriber QRZ Page

    Here's my guess (including stuff mentioned by others):

    The 4D32 was only made by Raytheon, so it didn't get the wide publicity of the 6146, which was developed by RCA and made by many companies. The 4D32 required the special 7 pin instead of the common octal for the 6146.
    When you look at the published ratings of the 4D32, it appears to be about the same or a bit less than a pair of 6146s. Sure, it can take a lot more, but the rigmakers weren't going to exceed the book ratings.

    But here's the Big Thing: Price!

    I checked the 1959 Allied catalog (almost every year is online!).


    It prices the 6146 at $5 each - $10 for a pair of RCA ones. A single 4D32 is priced at $30.95! In that same catalog, the 811A is $6.50 and the 813 is $22.65. That's for new tubes from a major supplier, not surplus.

    73 de Jim, N2EY
  4. N2DTS

    N2DTS Ham Member QRZ Page

    Well that explains it!
    Funny that you can get a new one now for less then the price of a new one back then....
    N2EY likes this.
  5. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

    Below are some Pulse tubes from left to right:

    RK-4D32, WE 5D21, JAN-4D32. What is interesting is the JAN-4D32 is taller than the RK-4D32, but both have the Raytheon branding clearly marked.

    The Western Electric 5D21 has a 26V filament.

    Thanks to Pat, KD5OEI for helping me identify the Western Electric 5D21.

    AC0OB - A Place where Thermionic Emitters Rule!
    Besides, when you're a Ham, you experiment with and improve boat anchors - that's what you do!. [​IMG]


    Attached Files:

    Last edited: Sep 12, 2016
    N6YW likes this.
  6. N2DTS

    N2DTS Ham Member QRZ Page

    I put the 4x150 rf deck back in and hooked up the dx60 screen modulator again (does 200 watts).
    Just felt like doing something.
  7. N2EY

    N2EY XML Subscriber QRZ Page

    Well, an NOS one....

    funny how the prices rise and fall.
  8. N2DTS

    N2DTS Ham Member QRZ Page

    Anyone ever hear of a pair of 4D32's as modulator tubes?
    Its ABOUT the same as two 6146 tubes and they were used as modulators in ab1 and ab2 at a20 watts a pair (always seemed to sound poor when I tried them).
    Two 4D32's should do around 240 watts of audio if its like four 6146's (roughly).
  9. WA3VJB

    WA3VJB Ham Member QRZ Page

    Heya Phil, I think there's some parallax or camera distortion that makes the JAN type toob look taller.

    Look where the pins are on the mat and you can see the discrepency there too.
    I recall that the glass and pins are the same.
    Someone told me the innards are the same, too, and that the JAN certification & labelling happened post-production with hand-selected and tested tubes that beat regular specs.

    AC0OB likes this.
  10. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

    You made me go back and actually measure the tubes. :p The base was actually a sofa seat cushion so you got me to thinking. I know, dangerous but necessary. :D

    There is a difference in total length but it is minute when placed on a flat board.

    The Ratheon on the left measured 5.250" total heigth and the JAN one on the extreme right measures 5.375."

    I measured the other JAN tubes and they were also the same 5.375" tall.

    This minute difference is in the measured pin length.

    But you are right, there is some optical distortion in the image.

    AC0OB - A Place where Thermionic Emitters Rule!
    Besides, when you're a Ham, you experiment with and improve boat anchors - that's what you do!. [​IMG]
    WA3VJB likes this.

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