[ARC5] Solid State Tubes

[Robert Eleazer]

In my first job after college, at Tinker AFB, I had a bit of an encounter with production solid state tubes, called "Fetrons."  Someone suggested that we replace some tubes with Fetrons.  The ones suggested for replacement were 12AT7's and 12AU7's and the like, in a temperature controller that drove a bleed air valve in the B-52D.  I discussed the application with the company and they confirmed that Fetrons were not universal replacements for tubes but had to be engineered for the specific circuit application.  I guess that the fact is that vacuum tubes are physically more fragile than solid state devices but are electrically more rugged.

Also, while I cannot find my copy of the article, I found a note that the April 1977 issue of QST magazine had an article on building solid state replacements for tubes using FETS and MOSFETS.  I built one or two of these and installed them in my National NC-155; they worked but for some reason knocked out the S meter function.  

And I found in my notes that the August 1962 issue of QST has an article on building a very simple 12 VDC  to 110V 60W AC inverter; it uses only a 110/24 VCT transformer, two PNP power transistors and 4 power resistors.  I built one and it  worked fine the first time I fired it up, which impressed me a great deal.

Wayne
WB5WSV