Vacuum tube to solid state
 

Is it at all possible to come up with a solid state replacement for a vacuum tube because one day tubes may be gone and with the solid state components out there these days why not.

Very easy if the tube is or is used as a diode. I had a 30s admiral that used a type 76 triode as a detector diode and someone in the 50s wired in an early 1N34 or 1N60 as a replacement.

I know people have made SS replacements for the 1L6 and the 6U5 (the 6U5 replacement is pure blasphemy in my book).

For linear amplifiers, transistors generally want lower impedance than tubes (less voltage, more current: smaller resistors, lower b+, bigger capacitors, smaller inductors.) Plus, a single transistor is unlikely to have the same characteristics as a single tube. Some combination of a FET with a bipolar transistor might be designed to come sort of close. However, the differences would be especially critical for circuits that depend on non-linear tube characteristics, like IF amplifiers with AGC or the color AFC control tube in your tube color TV.

Well I know about the rectifier that can be made but didn’t think it was that detailed for a tube to be converted so I hope tubes will be around for awhile.

Early solid state applications in TV was sound stages then RF and IF, lower voltages.

One problem solid state TV avoided was use of germanium transistors. My WID Motorola sets use silicon transistors.

Aging and long-hours audio equipment using T0-3 package germanium output transistors will get loud enough but sound poor with hissing highs as if not tuned in.

Probably possible if enough money could be thrown at it to develop specific tube function circuits, but it could never happen in a practical sense, because obviously the whole community of nostalgic tube lovers wouldn't want anything to do with it.

Hi Timmy,

When desirable tubes become rare enough, solid state replacements do begin to appear on the market, in this link you will find solid state replacements for several of the one volt tubes used in portable radios like the Zenith T/O. It started with the somewhat valuable 1L6 and 50A1, and now even more common types like the 1U4, 1U5, 3V4, and others are available.

Not my website, I have no affiliation with these tubes for sale whatsoever, I enclose this link only to show Timmy that what he is asking is already a reality in the old radio world......

https://picclick.com/Complete-Set-So...891821945.html

Except for the 1L6 and 50A1, the rest of those tubes are not expensive. All NOS below:

50A1 $29.00
1L6 $29.00
1U4 $4.50
1U5 $5.00
3V4 $6.00

All from Bob Dobush, Find-A-Tube.

Exactly.......;)

To me, it seems clear for some time now the supply of TV tube enthusiasts is dying out way faster than the supply of TV tubes. Prices of tubes used mainly in TVs continue to fall, and for good reason. There are thousands and thousands and thousands of TV tubes out there, new in box, that will never be used.

The same cannot be said for audio tubes, of course.

Even for CRTs, except for a few types, there are enough good ones out there to keep sets alive for TV collectors. I don’t mean 15GP22, but the supply of 10BP4 will last forever.

All that being said, solid state replacements for non-display tubes are generally possible to engineer.

Every bucket of tubes in my house seems to have one of those stupid 1B3s in it. I must have a million of them. Do they even go bad?

I sorted all my used pull 1B3s (and all other HV and focus rectifiers into 1/6 of a tube caddy....It seems like every time I find a bad one in a set (seems like 10-20% of sets) that I have to pull 3 from the caddy to get a good one.

Here and there when I can't find the type I need I just stick 2-6 R5000F 5KV PIV 200mA diodes in series solder an octal pin to one end and a tube plate cap to the other end and stick that in the TV...Seems to work about as well as a tube in many applications....In some cases (cough color TV focus rects cough) better.

R5000F is an old part #, not made anymore :/
now it's R5000F-T :yes:

Do they really hold up as a HV rect in a color set?

I'm happy I can remember the crux of the part number...Was finding them by refining the PIV specifications on mouser the first 2-3 times I bought them, but was able to remember enough of the number to search it this time.

They work great as focus rectifiers.

Several in series parallel did work in my 21CT55, and 4 in series worked for a Portacolor I didn't have a tube for earlier this year. The 21CT55 is a little hard on them and it took a few tries to create the right series parallel that would last more than a month in the doubler section. I think I ultimately went partially back to tubes in that set to balance HV level and output current.