This is a 5 tube TRF Neutrodyne radio. It came with a separate external use speaker transformer in a black wooden box-No. 5A. It has a three foot cable with connectors for input and binding posts for the speaker.

The input wires go to the plate and B+ connectors on the transformer and the output comes from the filament and grid connectors. It would appear to be a standard audio interstage transformer. The radio already has two audio interstages with final output off a 112A or 371A tube. There are speaker terminals on the terminal board.

If I measured the resistance correctly, the input is 360 ohms and output is 580 ohms. Is this a speaker matching transformer? I looked at the schematic and it doesn't help me much except leaving a question as to what went to terminals R1 and R2. Maybe, this black box? Any ideas?

Herman: I'm having trouble following your description of how the "black box" was hooked up. Can you refer us to the specific points on the schematic?

Whatever the "black box" is, it shouldn't be necessary to play the radio thru an old high-impedance speaker or a modern permanent magnet speaker thru an output xfmr.

R1 and R2 connect across the A voltage.My guess is that R1 and R2 connections were for the field of a dynamic speaker, if used. Surely not a night light :>)

:Herman: I'm having trouble following your description of how the "black box" was hooked up. Can you refer us to the specific points on the schematic?
:
:Whatever the "black box" is, it shouldn't be necessary to play the radio thru an old high-impedance speaker or a modern permanent magnet speaker thru an output xfmr.
:
:R1 and R2 connect across the A voltage.My guess is that R1 and R2 connections were for the field of a dynamic speaker, if used. Surely not a night light :>)

Thanks, Doug. You hit my problem on the head. It is labeled "Output Transformer". I have no idea how it was hooked up or even the need for it. It was loose in the cabinet of the radio when I picked it up years ago. It is made to go some three feet from the radio and have the speaker pin tips fasten to the binding posts on it. I'm going to part this radio out and I wondered what use this transformer might have and where it might have that use. Herman

Herman, this is a very nice radio - I hate to see you part it out.

Are the tuning gears shot? They can be replaced with a pulley arrangement.

And when you part it out, I doubt you'll find too much use for the parts.

Think about it.

:Herman, this is a very nice radio - I hate to see you part it out.
:
:Are the tuning gears shot? They can be replaced with a pulley arrangement.
:
:And when you part it out, I doubt you'll find too much use for the parts.
:
:Think about it.

::Herman, this is a very nice radio - I hate to see you part it out.
::
::Are the tuning gears shot? They can be replaced with a pulley arrangement.
::
::And when you part it out, I doubt you'll find too much use for the parts.
::
::Think about it.

What are the parts worth to you? i'd certainly like to have a crack at restoring this set, if you are not interested in keeping it anymore. I also have a barnfull of trades, should you have need of anything.

:::Herman, this is a very nice radio - I hate to see you part it out.
:::
:::Are the tuning gears shot? They can be replaced with a pulley arrangement.
:::
:::And when you part it out, I doubt you'll find too much use for the parts.
:::
:::Think about it.

:
:What are the parts worth to you? i'd certainly like to have a crack at restoring this set, if you are not interested in keeping it anymore. I also have a barnfull of trades, should you have need of anything.

Guys, I don't like to "destroy" collectables. If the only problem with this set were the shot potmetal tuning gears, I wouldn't separate it. I also know that almost anything can be restored and repaired. The cabinet was delaminating, not just the veneer. The cheap poplar core boards were apart, and the core was eaten up by wood worms. This is one of the worst pieces of furniture I have seen, but typical of the 1920's. To go on, the mouse damage was a disaster, creating disgusting rust and filth everywhere. I looked at this big, heavy radio for over ten years and finally said I had to fish or cut bait. I was prepared for some flak on this decision.

Some of the internal components are good and I would rather be an organ donor than bury the whole corpse at this time. I am putting some stuff up on Ebay now. Anyway, what is the black box for? Thanks, Herman

::::Herman, this is a very nice radio - I hate to see you part it out.
::::
::::Are the tuning gears shot? They can be replaced with a pulley arrangement.
::::
::::And when you part it out, I doubt you'll find too much use for the parts.
::::
::::Think about it.
:

Well, I see what you mean in this case. those cabinets make nice kindling, if they are not too damp, though. The box that was puzzeling you is an "Output filter. its purpose was to remove the DC component from the audio signal going to the speaker, and also to imorive the bass response a bit by resonating in the 150 cps area. it consists of an iron core choke across the output terminals, and a .5 or 1 MFD condenser coupling the loudspeaker to the signal.
:
::
::What are the parts worth to you? i'd certainly like to have a crack at restoring this set, if you are not interested in keeping it anymore. I also have a barnfull of trades, should you have need of anything.
:
:Guys, I don't like to "destroy" collectables. If the only problem with this set were the shot potmetal tuning gears, I wouldn't separate it. I also know that almost anything can be restored and repaired. The cabinet was delaminating, not just the veneer. The cheap poplar core boards were apart, and the core was eaten up by wood worms. This is one of the worst pieces of furniture I have seen, but typical of the 1920's. To go on, the mouse damage was a disaster, creating disgusting rust and filth everywhere. I looked at this big, heavy radio for over ten years and finally said I had to fish or cut bait. I was prepared for some flak on this decision.
:
:Some of the internal components are good and I would rather be an organ donor than bury the whole corpse at this time. I am putting some stuff up on Ebay now. Anyway, what is the black box for? Thanks, Herman
:
:

:::::Herman, this is a very nice radio - I hate to see you part it out.
:::::
:::::Are the tuning gears shot? They can be replaced with a pulley arrangement.
:::::
:::::And when you part it out, I doubt you'll find too much use for the parts.
:::::
:::::Think about it.
::
:
:Well, I see what you mean in this case. those cabinets make nice kindling, if they are not too damp, though. The box that was puzzeling you is an "Output filter. its purpose was to remove the DC component from the audio signal going to the speaker, and also to imorive the bass response a bit by resonating in the 150 cps area. it consists of an iron core choke across the output terminals, and a .5 or 1 MFD condenser coupling the loudspeaker to the signal.
::
:::
:::What are the parts worth to you? i'd certainly like to have a crack at restoring this set, if you are not interested in keeping it anymore. I also have a barnfull of trades, should you have need of anything.
::
::Guys, I don't like to "destroy" collectables. If the only problem with this set were the shot potmetal tuning gears, I wouldn't separate it. I also know that almost anything can be restored and repaired. The cabinet was delaminating, not just the veneer. The cheap poplar core boards were apart, and the core was eaten up by wood worms. This is one of the worst pieces of furniture I have seen, but typical of the 1920's. To go on, the mouse damage was a disaster, creating disgusting rust and filth everywhere. I looked at this big, heavy radio for over ten years and finally said I had to fish or cut bait. I was prepared for some flak on this decision.
::
::Some of the internal components are good and I would rather be an organ donor than bury the whole corpse at this time. I am putting some stuff up on Ebay now. Anyway, what is the black box for? Thanks, Herman
::
::

::::::Herman, this is a very nice radio - I hate to see you part it out.
::::::
::::::Are the tuning gears shot? They can be replaced with a pulley arrangement.
::::::
::::::And when you part it out, I doubt you'll find too much use for the parts.
::::::
::::::Think about it.
:::
::
::Well, I see what you mean in this case. those cabinets make nice kindling, if they are not too damp, though. The box that was puzzeling you is an "Output filter. its purpose was to remove the DC component from the audio signal going to the speaker, and also to imorive the bass response a bit by resonating in the 150 cps area. it consists of an iron core choke across the output terminals, and a .5 or 1 MFD condenser coupling the loudspeaker to the signal.

Bob, thanks. I feel better. In this case, I'm not throwing out the baby with the bath water. I didn't see a flat tin cap in there although it may be on top of the transformer which sure looks like an interstage audio transformer to me. Whatever it is, it'll go up on ebay along with whatever else I can salvage and clean up enough for pictures. I sure wish I had some potmetal tuning gears! I may even put my two bad ones up as one is pretty staight and might be saved by a good epoxy coating.

These radios are not common so parts demand might not be there, but I'll try. I think I got enough out of the tubes to cover my initial investment and I save them. I still have an AK 20 and what looks like a kit assembled TRF in the attic that use the 301a's, 201a's and 01a's. Herman
:::
::::
::::What are the parts worth to you? i'd certainly like to have a crack at restoring this set, if you are not interested in keeping it anymore. I also have a barnfull of trades, should you have need of anything.
:::
:::Guys, I don't like to "destroy" collectables. If the only problem with this set were the shot potmetal tuning gears, I wouldn't separate it. I also know that almost anything can be restored and repaired. The cabinet was delaminating, not just the veneer. The cheap poplar core boards were apart, and the core was eaten up by wood worms. This is one of the worst pieces of furniture I have seen, but typical of the 1920's. To go on, the mouse damage was a disaster, creating disgusting rust and filth everywhere. I looked at this big, heavy radio for over ten years and finally said I had to fish or cut bait. I was prepared for some flak on this decision.
:::
:::Some of the internal components are good and I would rather be an organ donor than bury the whole corpse at this time. I am putting some stuff up on Ebay now. Anyway, what is the black box for? Thanks, Herman
:::
:::