The FETron

[Opcom]

FETRON - ok where can I find the schematics for these little jewels?

http://www.philipstorr.id.au/radio/eleven/fetron.htm

They are not made any more but maybe they should be. No idea how to design them, esp. to plug in and use the high tube voltages and provide the reasonable frequency response for things like the HP 400 VTVM, audio, and I.F.s

If this could be done in the 1970's, imagine today with much better FETs.

[Pete, WA2CWA]

I have tubes in my VTVM and signal generator that have been in there for over 50 years and still work fine. I see no real advantage other then no filaments to heat up. Plus, I would suspect that fetrons are less tolerant to circuit diddling and the occasional slip of the probe(the inevitable OOPS moment).

Here's some info on their internal design and construction:
www.hrsasa.asn.au/docs/Fetron.pdf

[VE3ELQ]

Looks like an early version of an IGBT.

[W1ITT]

Back in the 1970s there was a fellow by the name of Howard Sartori who made some solid state tube replacements for the Drake R4 and T4x series.  He wrote an article that appeared in QST which, as I dimly recall, explained how to build the little buggers.  There were some hard-to-find high voltage FETs involved. 
A League member should be able to do a search of the magazine archives in this period for his article.  It won't provide you with a brand-name Fetron, but it might well put you on the trail towards cobbling up your own.  With this new-fangled goo-goo searching thing, you might even be able to track down the FETs, or some that would work.

[nq5t]

I'm surprised that FETrons almost never show up.  They were used by the bezillions in the telephone carrier networks in the 1970s. 

Maybe if one just knew which landfill to go dig in ….

[w4bfs]

tubesters

[Pete, WA2CWA]

Back in the 1970s there was a fellow by the name of Howard Sartori who made some solid state tube replacements for the Drake R4 and T4x series.  He wrote an article that appeared in QST which, as I dimly recall, explained how to build the little buggers.  There were some hard-to-find high voltage FETs involved. 
A League member should be able to do a search of the magazine archives in this period for his article.  It won't provide you with a brand-name Fetron, but it might well put you on the trail towards cobbling up your own.  With this new-fangled goo-goo searching thing, you might even be able to track down the FETs, or some that would work.

QST - April - 1977 - page 45
QST - Sept. - 1977 - page 38

[WBear2GCR]

There are several papers that can be found online.

Teledyne made them as Fetrons.
WE invented them, but made "fake" 6AK5s.
teledyne made various versions of the 6AK5s as well as triodes akin to 12AX7s.

These are based on work by Otto Schade. Really cool stuff that is.
They are old school discrete pre-SMD style construction, the top hat does nothing more than heat
dissipation afaik. Inside are two or more "transistors" in a "Schaded" circuit.

The Teledyne paper shows the basic idea, and a phtot of the guts.
I'd post it, but my HD crashed, and geeniass boy here did not have a good backup with the most recent stuff on it, and besided it's not on this laptop anyhow.

They are not exact drop in replacements for the equivalent tube. Close.

Ooops, looks like I found one of the pdfs on this machine... enjoy!
EDIT: file exceeds max size - maybe I can reduce.

Fwiw somebody had about 250 of these up on epay a few months back! Almost went for it, but most were
the 6AK5 type...

...they are not IGBTs at all, but today a HV FET of some sort might serve to build up a similar circuit.

                       _-_-bear

[Pete, WA2CWA]

There are several papers that can be found online.

Teledyne made them as Fetrons.
WE invented them, but made "fake" 6AK5s.
teledyne made various versions of the 6AK5s as well as triodes akin to 12AX7s.

These are based on work by Otto Schade. Really cool stuff that is.
They are old school discrete pre-SMD style construction, the top hat does nothing more than heat
dissipation afaik. Inside are two or more "transistors" in a "Schaded" circuit.

The Teledyne paper shows the basic idea, and a phtot of the guts.
I'd post it, but my HD crashed, and geeniass boy here did not have a good backup with the most recent stuff on it, and besided it's not on this laptop anyhow.

They are not exact drop in replacements for the equivalent tube. Close.

Ooops, looks like I found one of the pdfs on this machine... enjoy!
EDIT: file exceeds max size - maybe I can reduce.

Fwiw somebody had about 250 of these up on epay a few months back! Almost went for it, but most were
the 6AK5 type...

...they are not IGBTs at all, but today a HV FET of some sort might serve to build up a similar circuit.

                       _-_-bear

The link in my post above is the Teledyne paper showing the innards. No reason to post it twice.

I thought Otto Schade did study work leading up to the Nuvistor.

The WECo version, called Hybrid Integrated Networks (HIN), was conceived by Bell Labs/WE Engineers. However, actual manufacture of the HIN's was done by several outside manufacturers. I believe Teledyne was one of those manufacturers. WECo HIN's were branded with ID's like KS-21077, KS-21078, and several others.

[WBear2GCR]

Yes, Pete, I thin k that is the same paper/pdf.
Unfortunately today this evening Time Worthless Cable did not want it to load. So I could not verify.

If you look at Shade's work on composite vacuum tubes and the schematic for the Fetron, the relationship seems pretty straightforward. That was a really sharp cookie! I did not know he was involved with the Nuvistor... another very cool innovation.