Another interesting find

[T-Ruxx]

I found this down at the local Thrift store. It's a Amrex Electrical Inst. Co. Model SW. 504 . I googled it , the outfit is still in business, this unit was on the history page , made in 1950. I guess it's a short wave muscle stimulator . Here's a definition I got off the internet.

shortwave diathermy
Sports medicine Diathermy that delivers shortwave frequency electromagnetic waves; SD is used for chronic inflammation–eg, bursitis, neuritis, osteoarthrosis, rheumatoid arthritis, strains, tendinitis, etc Contraindications ASHD, hemorrhage, metal implants, infections, malignancy, pacemakers, phlebitis, pregnancy, wet dressings

This thing has no plug on the cord, and I have no plans on firing this thing up. It's kind of spooky, like something you'd find in an old haunted mental ward. I could see zombies or dawn of the dead type scenario . All kidding aside, I thought is was cool, and I would gut it out and use it for a head cabinet. It's got some serious tubes in it, the one on the left is broke, the others look fine. It's kind of fun to find these old electronic gagets. later Greg

[M Fowler]

Must be the first EMG/NCV machine neurologists like to hook you up to.

Mark

[M Fowler]

Double post again.

[NowFender]

Maybe a framed b/w photo of Boris Karloff...some Tesla coils fired up on the side! And if they are still in business what do they make now?
spooky.

They make fans and toaster ovens...so they cool people down and cook their food..instead of cooking the people.

[Phil_S]

Way cool! You've got a 6B4G tube, which the RCA manual describes as a Power triode. Regular 6.3v filament supply @ 1A. Va=250, Vg=-45, Ia=60mA, load=2500 ohms, output 3.5W. If it's still good, you've got the makings of a viable SE amp there.

[drhulsey]

Its job was to produce heat in the treated area. Nowadays, the physical therapist just pulls a hot pack out of the warmer. We went from high tech to lo tech

[Wayne]

It's a shame that 813 is busted - 2 in push-pull will deliver 500 W of audio.

Can you hear me now???

W

[Wayne]

What are those two little darlins on the right with the plate caps?

W

[Structo]

Kewl!

I had a portable Zenith radio years ago that had fake alligator covering on it.

It took gobs of batteries as it was a battery powered tube radio.

It had real B+ power.

[T-Ruxx]

Left to right the tubes are as follows. The 813 was a sylvania made in USA, but the top is broke . The middle one is a RCA 6B4G (Phil_S , you win the prize) ,it appears intact. The two on the right are : GE 866A made in USA, and extreme right is an Amperex 866AX made in Holland. They look good too. To a newbie like me it's all Greek, but I'm willing to learn.
I'd like to thank you all, you guys are by far the nicest, friendliest group of builder's I've ran across. Other forum's , I'm either beneath them, or I feel stupid for asking a question. I guess they forget that they all started somewhere. Thanks again ,Greg

[Phil_S]

The data sheet says the 866A is a half wave rectifier. They require a 2.5V supply and draw 5A each! PIV=10,000 and IRect=250mA. So, this is a pretty heavy duty tube. I am guessing two were employed to make a full wave rectifier? IMO, these would not be used today. At best, I think they are conversation pieces. See if you can clean them up and make a sculpture with them.

I'm wondering though, in terms of the transformer that was supplying these tubes, it is possible that you have a 5V 10A winding and the cathode/filaments were in series. You'll need to look inside to get the answer.

Then, there is the 813, which is supposed to be a great old-time power triode, which requires a filament supply of 5V at 10A! (Maybe there are two 5V 10A windings, as rectifier and other tubes should not share the saem supply.) The spec sheet lists typical plate voltage between 1250 and 2000 volts at 180mA plus 20mA for the screens!

I'm thinking the plate supply is way too high to be useful in a modern day guitar amp. But the filament supply(ies) run through a voltage multiplier circuit could easily supply a 20-40W amp with plate voltage in the low to mid 300's .

The 6B4G has a 6.3v filament, so you might just be lucky enough to get enough Amps to supply some modern tubes.

I'm thinking you've got some monster transformer(s) in this item. How about you open it up and show us some pix? Be careful in there, even old caps can hold a lethal charge. You'll want to discharge them properly even though they are probably dead as doornails.