Discussion in '"Boat Anchor" & Classic Equipment' started by K7WXW, Jun 11, 2019.
The QST article says the FETRON is rated for 100,000 hour life!
are these Fetrons or Tubesters??
PS. if someone happened to forward that QST pdf, I'd be appreciative - "I'm 'good" on QRZ"
"My 32S1 has eight of them, that were there when I bought it, and it works OK. Haven't had a problem with it so..."
Mike, what are those things stuffed into V3 and V4? Fetrons with the lids removed?
I wonder, "use life"?
or "existence life"?
Using the QST article date (given that FETRON was made around that same date),
say February 1973 to roughly February 2019, and not taking leap years into consideration, that would be 402,950 hours for the FETRON.]
Shake it to see if it still works
The Tubesters and the original Western Electic HIN were made with discrete parts.
The Fetrons are hybrid circuits, built flat on the bottom, the cap being for convenience
and similarity to the tube...
I don't know, but based on your description they would be tubsters.
In my first assignment in the USAF we received a suggestion that we replace the 12AT7, 12AU7. etc, in some B-52 bleed air valve controllers with Fetrons. I recalled a magazine article on Fetrons, looked into it and the company confirmed to me that there were no universal replacements for tubes. Each application required some specific engineering be done, but most of the time it did take much.
After I went on to another assignment one of the other engineers took up the challenge of upgrading some Air Force equipment with Fetrons. As I recall the company as not doing too well and was hoping to get a military contact. I don't know what occurred.
I have built some solid state replacement tubes myself, following the instructions in a late 70's issue of QST to build a replacement tube for my National NC-155. The biggest problem was the scarcity of high voltage FETs. Lately I stumbled onto some plans I had downloaded a while back for building solid state replacements for the tubes in the GRC-9 receiver. I built a replacement LO tube and it worked very well, operating on the original 105 VDC B+ used by the set. My next discovery was that all but one or two of the original resistors in the set had gone well past their 10% tolerances, on the high side. Replacing those and locating suitable modern resistors was a fairly lengthy chore. I then built a solid state 1L4 for the 1st IF tube but have not tested it yet due to the need to finish replacing the IF transformers.
By the way, building suitable tube plugs was a significant task in its own right. They are scarce and the 7 pin ones are all but nonexistent. I used my drill press, a circle cutter, and some thin phenolic built up in layers to make the sockets and had to order the proper size solid copper wire for the pins, a size that is not commonly available.
Not the same thing, but I converted my Heathkit IG-102 sig gen to FETs, from an old article in one of the magazines by Julian Rossnick, "The IG-102 goes Transistor!" The tubes were 12AT7s for the RF oscillators, and a 6AN8 tride-pentode as the 455 kHz oscillator and the pentode the output amp. I uses 2N5486 JFETs due to their closer idiss specs. It worked well, and I mounted a 9V battery in a clip on the chassis. Obviously, the FETs were reduced in HV and bias supplies with resistors that I put in with the ones in the rig. Nice portable unit, and I took a lot of scope and spectrum analyzer pictures. A few months later, I undid the conversion.
They used the 1002 (iirc from the earlier post) as a direct plug in replacement for the
6AK5 in the Heath VTVM... and the other for a 12AX7.
Otoh, they offered a whole slew of "6AK5" models!
Some had a diode internally in the cathode, I'm not sure what the idea is/was there,
except maybe for biasing the grid?
Their literature, the stuff I have been able to find is limited in engineering advice
as far as applications. IF there was a whole family of curves and specs for the various
models, that would make it easier to decide how to engineer the circuit modifications.
While there are high voltage Mosfets today, I'm not aware of any JFETs.
If there were some, I'd try my hand at a DIY version...
As far as 7 and 9 pin "plugs", I think they can be had... probably even on epay?
The devices I have are definitely Fetrons. I am trying to decide whether I want to build something interesting with them or find them a new home. Probably the latter given the number of projects I have sitting around here, waiting to be accomplished! That said, I am going to hunt for the QST article...