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Author Topic: The Johnson Thunderbolt II amplifier, did it ever exist?  (Read 4695 times)
N6YW
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Posts: 42




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« on: April 21, 2013, 09:28:27 PM »

Greetings to the forum.

I am about to take ownership of a Johnson Viking Avenger HF transceiver. In the manual, it shows the associated optional accessories and one of them is a vastly cosmetically updated version of the Thunderbolt amplifier that matches the look and
aesthetics of the Avenger called the Thunderbolt II. Along with the Avenger which is extremely rare, I would hazard a guess
that it never actually went into production due to the fact that EF Johnson scuttled the Avenger project before it ever hit the market. Judging by the styling of the updated Thunderbolt II, I am willing to bet that they scuttled this idea too, or did they?
Has anyone ever seen such a model? If you're curious, you can log onto mods.dk and download the Avenger manual which is a trip unto itself, and see the amplifier in a rendered form, along with a matching external speaker which is surely quite rare if not impossible to find. If indeed the Thunderbolt II amplifier made it to pre production form, it's likely a couple of examples exist somewhere. Could you imagine my thrill of finding one to match up with the Avenger? It's likely impossible but you never know.
Any comments?
73 de Billy N6YW
« Last Edit: April 21, 2013, 09:42:14 PM by N6YW » Logged
K8AC
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« Reply #1 on: April 22, 2013, 09:25:31 AM »

Can't help with the Thunderbolt II info, but thanks for posting this question.  I looked for an Avenger for many years, but never ran across one.  I downloaded the manual from mods.dk and found the Thunderbolt II photo and info - very interesting.  The Avenger manual reminds me of a Heathkit manual from the same period - full of explanations on how the circuits function and troubleshooting info (it was assumed that you were going to try and fix it yourself!).  I was a bit surprised on the Avenger to see that they really didn't accommodate CW operation very well - no narrow filter option and the CW offset was apparently fixed at 1 KHz.  I believe some of the Collins S-Line gear used a similar CW offset, making transceive operation on CW somewhat cumbersome.  Anyway, best of luck in locating a Thunderbolt II.  That and the Avenger would indeed be a one-of-a-kind station.

73, Floyd - K8AC
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N6YW
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Posts: 42




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« Reply #2 on: April 22, 2013, 09:47:31 AM »

Floyd
Thanks for the reply.
In all of my years of collecting and restoring radios, I have never run across any mention of the Thunderbolt II. I own an original series Thunderbolt in nice working condition and hopefully will have the Avenger running and paired with it. I am fortunate enough to have the original manual and some spare boards including 2 power supplies. Anyway, a bit off topic.
What I find to be interesting about the advertisement in the manual is that it suggests that EF Johnson was gearing up internally for production. They had a scheme worked out, even if it was an artistic rendering and it was committed to print.
To me, this sort of points to doing things backwards, unless the suits upstairs called off the project before it could become
a reality. I would love to uncover the history of that project.
Billy N6YW
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WA2CWA
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« Reply #3 on: April 24, 2013, 12:40:36 AM »

I have an original E. J. Johnson brochure (Form No. 900-Z-078) that showcases the Avenger, Thunderbolt II, and several accessories. I even have the 8S size schematic (Drawing Number D-025-0848-001) print of the the Thunderbolt II dated 4-5-71. I believe I read and/or someone told me that the Thunderbolt II appeared as a Henry Tempo (something) amplifier for a short period of time. Given that Johnson were pretty much out of the ham radio transmitter business by the late 60's/early 70's, it's possible that maybe the amplifier was going to be manufactured by Henry and sold under the Johnson name. With the Avenger project dead, there was no reason to further market and produce a Thunderbolt II under the Johnson name.

Pete, wa2cwa
 
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N3QE
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« Reply #4 on: April 24, 2013, 01:32:05 AM »

I believe I read and/or someone told me that the Thunderbolt II appeared as a Henry Tempo (something) amplifier for a short period of time.

Henry Tempo 2000? It's a low-res picture... but it looks like it has some of the same Avenger-like styling:
http://www.eham.net/reviews/detail/8977

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N6YW
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Posts: 42




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« Reply #5 on: April 24, 2013, 10:47:09 AM »

I have an original E. J. Johnson brochure (Form No. 900-Z-078) that showcases the Avenger, Thunderbolt II, and several accessories. I even have the 8S size schematic (Drawing Number D-025-0848-001) print of the the Thunderbolt II dated 4-5-71. I believe I read and/or someone told me that the Thunderbolt II appeared as a Henry Tempo (something) amplifier for a short period of time. Given that Johnson were pretty much out of the ham radio transmitter business by the late 60's/early 70's, it's possible that maybe the amplifier was going to be manufactured by Henry and sold under the Johnson name. With the Avenger project dead, there was no reason to further market and produce a Thunderbolt II under the Johnson name.

Pete, wa2cwa
 
Pete
Nice to see you here, we met on the AM Fone site.
This totally makes sense and it seems to be exactly what happened. I should be able to find one of the Tempo amplifiers easily. I wonder if Uniden did the actual manufacturing for Henry like the Tempo transceivers.
Thanks for the postings gentlemen. This history is fun for sure.
73 de Billy N6YW
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