The Return of the Vacuum Tube?

Discussion in 'Amplitude Modulation' started by W8KHK, Jul 25, 2019.

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  1. W8KHK

    W8KHK Ham Member QRZ Page

    N6YW likes this.
  2. AC0OB

    AC0OB Subscriber QRZ Page

    ...The obvious conclusion, previous fears aside, was that even the Soviet Union’s most cutting-edge technology lagged laughably behind the West’s...

    The obvious conclusion was their electronics could survive and tolerate radiation and EMP effects better than our all-solid-state equipment.

    We had to make our electronics on Insulating Substrates, use SOS technology (more complex and costly), and shield the heck out of the electronics bay (which added weight) in order to mitigate radiation and other EMP effects.

  3. W8KHK

    W8KHK Ham Member QRZ Page

    Well, that was the 70s.... Maybe they were not that far behind us. I worked Comm-Nav, Radar, IFF, and Weapons Release Computer on the McDonnell Douglas F4C Phantom II up until late 1970. The radar system was loaded with mostly tubes, and I am not talking about just the magnetron or klystrons. Except for the microwave mixer diodes, the receiver, synchronizer, antenna positioning, and modulator as well as the displays, were ALL hollow-state. Can you believe 6AS7s (6080s) driving magnetic amplifiers to actuate the hydraulic valves in the antenna actuators! And 6336s (the 6080s big brother) as high-voltage power supply regulators.

    The only area where a large number of discrete transistors were employed was the image display generator on the port side behind the RIO seat. It was affectionately known as the "Germanium Display Controller". It had a much higher failure rate than any of the tube-laden functions!

    The entire computer system that controlled lock and guidance for the Sparrow Air-to-Air missiles was loaded with dual pencil-triodes, 6111 and 6112 in abundance, the tiny sibling of the 12AX7 and 12AT7. Not a transistor to be found! The F4D, and later the F4E, eliminated many of the bottles, and therefore were much more prone to the EMP effects.
  4. AC0OB

    AC0OB Subscriber QRZ Page

    I worked at McDonnell Douglas Astronautics (MDAC) [Cruise Missile development] and then at McDonnell Douglas Microelectronics (MDEC) [NSA and Darpa sats., AV8B, and B-52 avionics upgrades] from '78 to '87.5 and the Ruskies were still using tubes but we had switched to nuclear hardened custom SOS IC's.

    My Dad worked for MDC from '57 to '75 and was involved in the design of the F2H Banshee, F4 Phantom series, and the Mercury spacecraft.

    Last edited: Jul 27, 2019
  5. W8KHK

    W8KHK Ham Member QRZ Page

    Ahh yes, SOS, not sure if there is more than one acronym, but at HP that was Silicon on Sapphire, and it paved the way for Hp to move from TTL standard logic to three custom chips in their HP-3000 Series 33 minicomputer. High speed and low power consumption incomparable to anything else available at the time. The B-52 has lived a very long and productive life, and is still less maintenance cost per flight hour than many of the other options available. You have had a rich and interesting career.

    I would be interested in what systems your dad worked on regarding the Phantom series. If on the APQ-109 and later derivatives, he must have also had a major positive impact on development. Very little of the radar system in the F4-C was retained on the D and later versions. I spent so much time on that vacuum tube computer I can still recall many of the circuits used!
  6. WZ5Q

    WZ5Q Ham Member QRZ Page

    My Grandfather worked for them in California as a chief engineer way back from the 50's until retiring in the 70's. IIRC, it was Douglas Aircraft Space Systems back then till the merger, then it became McDonnell Douglas Astronautics Company (MDAC).
  7. AC0OB

    AC0OB Subscriber QRZ Page

    Yes, Silicon on Sapphire in both analog and digital domains but mostly digital; CMOS on SOS had kind of a neat ring to it.

    The farthest man-made object from the earth, the Voyager 1 spacecraft, has an RCA-built SOS microprocessor aboard it. It was launched in 1977 and left our solar system in 2003. As of January 2006 it was 14 billion kilometers from earth and still functioning.

    from a very interesting article on the history of SOS:

    and the actual implementation:

    My dad was not involved in any electronics or avionics designs. He would have designed the mechanical spaces for the avionics of the F2H and F4's. The last project he worked on was the F-15.

  8. W8KHK

    W8KHK Ham Member QRZ Page

    Phil, Hats Off to your Dad. In all the work I did on the Phantom, I was thankful how accessible all the system components were arranged, easy to install and cable. The only challenging task was display alignment. It was usually completed more easily and switfly with two people, one to observe the display, and the other to tweak the multitude of pots on the display controller behind the RIO seat. All in all, the work on the flightline was enjoyable. The entire forward section of the radar was mounted on a ball-bearing track, which would easily extend over three feet when the radome was opened, making everything easily serviceable.

    Thanks for the links on the SOS ....
  9. W9BRD

    W9BRD Ham Member QRZ Page

    One of the tubes in my junkbox for QRP-amplifier play is the mid-1950s-vintage 9-pin miniature 6216 beam power tube, per its specs designed and high-vibration tested/certified for use in military jets. One of its spec subsets shows its use as an "electronic filter reactor"--the pass tube in a regulated power supply. Do any of you folks know how it was actually applied in mil service?
  10. AC0OB

    AC0OB Subscriber QRZ Page

    I would have to assume that it took the place of a physically large inductor.

    I.e, it simulated the action of an inductor much as we can simulate an inductor with an opamp.

    See sec. 4.4 of this link:


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