Who owns a Johnson Thunderbolt?

Discussion in '"Boat Anchor" & Classic Equipment' started by KE0ZU, Feb 16, 2018.

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  1. KE0ZU

    KE0ZU Ham Member QRZ Page

    I'm curious about how many own these old amplifiers. I suspect they were one of only a small handful of old amps that can operate in WARC bands.
  2. W7UUU

    W7UUU Super Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    This thread is nowhere near as fun without a photo :) [NOT MINE]


    N7ANN likes this.
  3. W2VW

    W2VW Ham Member QRZ Page


    Here's mine. Some idiot must have modified the thing so I may just put it out on the curb.
  4. WA2CWA

    WA2CWA Ham Member QRZ Page

    I have both a Johnson Thunderbolt and a Johnson 6N2 Thunderbolt.
    At one point, I had two Thunderbolts but took one to Dayton and found it a new home.

    My Johnson Courier and Heathkit SB-200 can operate in the WARC bands.
  5. KE0ZU

    KE0ZU Ham Member QRZ Page

    Thanks for the pics guys.

    I bought my thunderbolt last week after doing a "test drive", and will go get it this coming Wednesday. Not a "Desk" but close enough, for now. ;)
    Last edited: Feb 16, 2018
  6. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    Remember, the Thunderbolt is a grid driven amplifier and not a grounded grid amplifier. Even with exciters like the Johnson Ranger, an attenuator was required. There are instructions, in the manual, for building attenuators for exciters like the Ranger and for exciters in the 100-watt category.

    Unfortunately, those attenuators are for exciters with pi-network outputs that can match a fairly high impedance. Modern exciters, with the 50-ohm fixed output circuits, will not work with these attenuators. For modern, 100-watt output exciters, you need an attenuator for between 10 dB and 12 dB to get the driving power below 10-watts.

    I don't own a Thunderbolt. However, I have, over the years, worked on a few for others.

    Pay close attention to the control circuitry that is also outlined in the manual. You have to switch between the operating bias and the blocking bias. This is controlled through a 4-pin jack that is the same as the olde tyme microphone jacks used for commercial FM equipment. A plug, from a Motorola microphone, will work if the screw holding the insulator in place is removed and the pins rotated about 15-degrees. The connector used on other brands of two-way equipment fit the jack without modification.

    Glen, K9STH
    N2EY likes this.
  7. AI0K

    AI0K Ham Member QRZ Page

    Why would you EVER put such a beautiful piece equipment on the curb? Even if someone modified it, it's still a treasure - and should be able to restored.
  8. KB4MNG

    KB4MNG Ham Member QRZ Page

    I operated one for about a year. It was in junk condition but with the help of this forum, got it going. I put in solid state rectifiers which I found out, put stress on the old components and smoked a transformer. I sold it as a project to a local ham.

    It is a very cool amp. I designed a relay system for it so I could use it with my 520 and made many cw contacts with it.

    The main problem I had was the amount of "juice" required. Check your electric meter with the amp on verses off. Mine was wired for 110v.
  9. W7UUU

    W7UUU Super Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Pretty sure he was using his "being silly font" :)

    N7ANN and W2VW like this.
  10. KP4SX

    KP4SX XML Subscriber QRZ Page

    What a beautiful sight!
    W2VW likes this.

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