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Was there ever any vacuum tube spectrum analyzer out there?

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neazoi

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Was there ever any vacuum tube spectrum analyzer out there?
The closest thing I have come across is these IF "spectrum monitors", or "scanalyzers", or "panadapters", or "band scopes". They are narrow range spectrum analyzers close to a preset IF frequency. So my question is, was there any spectrum analyzer that used exclusibely tubes, like the old HP or Tek scopes did?
 

I'm sure they existed but I don't know any specific models. A search for "wobbulator" might lead somewhere.

Brian.
 

    neazoi

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I'm sure they existed but I don't know any specific models. A search for "wobbulator" might lead somewhere.

Brian.
I know that there were plugins that could convert a tube scope to a spectrum analyzer, that's all I know.
 

1l20 AND 1l40 plugins for TEK 54X TUBE Mainframe were a hybrid tube/discrete
transistor solution. I thinks thats true also of the 1L10 and 1L30.

1650055553821.png


The HP141T is a CRT and Transistor solution.

1650055726355.png


Regards, Dana.
 

    neazoi

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1l20 AND 1l40 plugins for TEK 54X TUBE Mainframe were a hybrid tube/discrete
transistor solution. I thinks thats true also of the 1L10 and 1L30.

View attachment 175489

The HP141T is a CRT and Transistor solution.

View attachment 175490

Regards, Dana.
Yes, not really pure tube things.
Here is the Heathkit SB-620 which is fully tube-based, but as said, it is only narrow IF, intended for band analyzer in old transceivers, not a real wideband lab spectrum analyzer.
There were also many older military such sets, but no real tub-based spectrum analyzers. I wonder such gear first came out for the first time.
 

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Even the 620 is not "pure", it has diodes in it (solid state) and a varicap as well.

But as close as you can get I would guess.


Regards, Dana.
 

Even the 620 is not "pure", it has diodes in it (solid state) and a varicap as well.

But as close as you can get I would guess.


Regards, Dana.
Obviously I refer to the main circuit, the stages if you want. One or two "helper" diodes (eg in the PSU or varicaps), I do not think qualify the equipment as solid state. Only WWII equipment for example used pure tube PSU rectification.
The first complete SA of TEK I am aware of is the 491 and this is solid state (apart from some planar triodes in the OSC circuits). The older ones seem to be SA plugins for scopes.
 

I have a number of Amateur Radio receivers that use tube rectification built thru the 50's into early 60's.
And some test equipment as well. As well as seleniums in some. Then the hybrid stuff started showing up,
like the 1L10, 1L20, 1L30, 1L40 I have as well as the long history of transceivers with tube finals.

It will be interesting if anyone can reveal if there were in fact total tube wideband analyzer and when it was
manufactured.


Regards, Dana.
 

Polarad SA-84W looks like being mostly tube based. http://www.museum-nt.de/objekte/polarad_sa_84wa.html
At least this "panadaptor" uses tubes Polarad SA-8B http://www.polarad.com/Manuals/Panoramic_SA-8B_Manual.pdf, a spectrum analysis adaptor connected to an existing RF receiver on the IF level, models with 455 kHz and 5.25 MHz input. There are possibly earlier Polarad instruments to be considered.

Pentrix, who developed the Tek 1L10 and was later overtaken by Tektronix is a Polarad spin-off. https://vintagetek.org/tektronix-spectrum-analyzer-business/
 

    neazoi

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Polarad SA-84W looks like being mostly tube based. http://www.museum-nt.de/objekte/polarad_sa_84wa.html
At least this "panadaptor" uses tubes Polarad SA-8B http://www.polarad.com/Manuals/Panoramic_SA-8B_Manual.pdf, a spectrum analysis adaptor connected to an existing RF receiver on the IF level, models with 455 kHz and 5.25 MHz input. There are possibly earlier Polarad instruments to be considered.

Pentrix, who developed the Tek 1L10 and was later overtaken by Tektronix is a Polarad spin-off. https://vintagetek.org/tektronix-spectrum-analyzer-business/
It seems there were quite a few polarad models from that era designed from scratch as SAs. 10MHz to about 40GHz.
I am curious why companies like hp or tek did not get into this field in the tubes era.
 

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Back in the WW2 tube days, the only way to make an electrically sweepable RF oscillator was with a mechanically driven capacitor. I actually possessed one of the infamous wobulators at one stage when I was in my early teens.

As I remember, it was a round metal can with one fixed and one movable capacitor plate. The fixed plate was connected to the metal can, which was of course grounded.
The movable plate was activated by a solenoid and very likely a spring. The evil thing would buzz, and rattle loudly if over driven. It was horribly unstable, or maybe I was doing it all wrong ?

Wobbly old wobulator is very aptly named.

If you have never seen one, you have not missed much.
 

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