I'm considering using 3s4 tubes as uv199 substitutes and have a few questions. Are there better choices? How what is the best way to wire the adapter to make this pentode work as a triode? Thanks.

Hi Wayne

There are other choices but 3S4 is as good as any. Other tubes with 3 volt filaments are 3Q4, 3V4, 3Q5 etc. You could also use a 1 1/2 volt tube by adding a resistor. One tube I like is 5676. It's a 4 pin triode with solderable leads. 7 pin miniature tubes require a socket. Their pins are almost impossible to solder.

The best way to make a triode out of pentode is connect outer grids to plate. In most you can't separate grid #3 but it has little effect. Just connect grid #2 to plate as use this as plate of your UV199.

Do you have a base? You can use one from a dud or make your own. Plastic sprinkler pipe end cap will work but for UV199 takes some work. Diameter has to be very close to fit the socket.

Norm

:I'm considering using 3s4 tubes as uv199 substitutes and have a few questions. Are there better choices? How what is the best way to wire the adapter to make this pentode work as a triode? Thanks.

I have found that 1" dowel rod will fit the tube sockets perfectly. I have some 7 pin chassis mount sockets with holes in the middle that can be secured to the dowel with a wood screw. The pins can be made from tiny brass wood screws to which small guage insulated wire can be run from the miniature socket. The dowel can be slotted to allow the connections to be flush. A small nail will suffice for the stud.
:
: There are other choices but 3S4 is as good as any. Other tubes with 3 volt filaments are 3Q4, 3V4, 3Q5 etc. You could also use a 1 1/2 volt tube by adding a resistor. One tube I like is 5676. It's a 4 pin triode with solderable leads. 7 pin miniature tubes require a socket. Their pins are almost impossible to solder.
:
: The best way to make a triode out of pentode is connect outer grids to plate. In most you can't separate grid #3 but it has little effect. Just connect grid #2 to plate as use this as plate of your UV199.
:
: Do you have a base? You can use one from a dud or make your own. Plastic sprinkler pipe end cap will work but for UV199 takes some work. Diameter has to be very close to fit the socket.
:
: Norm
:
::I'm considering using 3s4 tubes as uv199 substitutes and have a few questions. Are there better choices? How what is the best way to wire the adapter to make this pentode work as a triode? Thanks.

Wayne

Sounds like a great idea. The dowell is already sized and wood screws will work for pins. You can even paint it black.

Norm

:I have found that 1" dowel rod will fit the tube sockets perfectly. I have some 7 pin chassis mount sockets with holes in the middle that can be secured to the dowel with a wood screw. The pins can be made from tiny brass wood screws to which small guage insulated wire can be run from the miniature socket. The dowel can be slotted to allow the connections to be flush. A small nail will suffice for the stud.
::
:: There are other choices but 3S4 is as good as any. Other tubes with 3 volt filaments are 3Q4, 3V4, 3Q5 etc. You could also use a 1 1/2 volt tube by adding a resistor. One tube I like is 5676. It's a 4 pin triode with solderable leads. 7 pin miniature tubes require a socket. Their pins are almost impossible to solder.
::
:: The best way to make a triode out of pentode is connect outer grids to plate. In most you can't separate grid #3 but it has little effect. Just connect grid #2 to plate as use this as plate of your UV199.
::
:: Do you have a base? You can use one from a dud or make your own. Plastic sprinkler pipe end cap will work but for UV199 takes some work. Diameter has to be very close to fit the socket.
::
:: Norm
::
:::I'm considering using 3s4 tubes as uv199 substitutes and have a few questions. Are there better choices? How what is the best way to wire the adapter to make this pentode work as a triode? Thanks.