03-19-2023, 07:44 PM
Bob,
Open coils are the bane of us radio collectors
Although this particular speaker uses windings in glassine layers, plain scramble winding will work with some loss of high frequency.
Need to make any kind of suitable winding jig that can support the bobbin, of which may have to have "cheeks" made to prevent fall of the winding during the process. The wire size will be at least #40 possibly smaller. Manual tension should be used so it will take practice. Essentially, fill the bobbin. Terminating the wire with .025 solder braid such that the braid is locked under Kapton or similar tape.
There are a LOT of ideas here:
https://www.radiomuseum.org/forum/rewind...hones.html
Especially important is the winding direction in respect to each bobbin, if would incorrectly the forces will be in opposition to that of the magnet.
I would expect that each coil be at least 500 ohms DC resistance, preferred would be 1K DC resistance total for the two coils of 2K. That very roughly equates for a tube plate impedance of 10K ohms.
Replacement with a modern speaker and an output transformer is often met with very low volume and distortion as there is usually a mismatch of the output transformer and very low efficiency from a moving coil speaker.
Chas
Open coils are the bane of us radio collectors
Although this particular speaker uses windings in glassine layers, plain scramble winding will work with some loss of high frequency.
Need to make any kind of suitable winding jig that can support the bobbin, of which may have to have "cheeks" made to prevent fall of the winding during the process. The wire size will be at least #40 possibly smaller. Manual tension should be used so it will take practice. Essentially, fill the bobbin. Terminating the wire with .025 solder braid such that the braid is locked under Kapton or similar tape.
There are a LOT of ideas here:
https://www.radiomuseum.org/forum/rewind...hones.html
Especially important is the winding direction in respect to each bobbin, if would incorrectly the forces will be in opposition to that of the magnet.
I would expect that each coil be at least 500 ohms DC resistance, preferred would be 1K DC resistance total for the two coils of 2K. That very roughly equates for a tube plate impedance of 10K ohms.
Replacement with a modern speaker and an output transformer is often met with very low volume and distortion as there is usually a mismatch of the output transformer and very low efficiency from a moving coil speaker.
Chas
Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
