I've noted that the coil wire is composed by 3 independent wires as thin as a human hair (each one) and twisted togheter then cloth covered.
Anyway the final wire is thin enough.

Lets suppose that I need to rewire this coil.
To find this cable is near to impossible so here's the million dollar question:

¿Can be used a modern single wire of a proper gauge to reach the resistance that was given with the original?

i am not sure, but see no reason why once you have achieved the correct resistance it will not work. There is also the need to have the inductance correct- if correctly wound- should work

:I've noted that the coil wire is composed by 3 independent wires as thin as a human hair (each one) and twisted togheter then cloth covered.
:Anyway the final wire is thin enough.
:
:Lets suppose that I need to rewire this coil.
:To find this cable is near to impossible so here's the million dollar question:
:
:¿Can be used a modern single wire of a proper gauge to reach the resistance that was given with the original?
:

Milton,
Its called Litz wire, and is typically cotton covered over the stranding. It was found in many AM radio applications, including solid state hardware. The multi stranding lowers the interwinding capacitance turn to turn. Its use is primarily for high inductance/low power, where hundreds of turns are needed and interwinding capacitance would become an appreciable part of the circuit (in parallel) Even with the same inductance, I suspect single strand of the same overall guage would severly compromise the circuit and produce unwanted results.
marv

:I've noted that the coil wire is composed by 3 independent wires as thin as a human hair (each one) and twisted togheter then cloth covered.
:Anyway the final wire is thin enough.
:
:Lets suppose that I need to rewire this coil.
:To find this cable is near to impossible so here's the million dollar question:
:
:¿Can be used a modern single wire of a proper gauge to reach the resistance that was given with the original?
:

This "Litz" wire is available from www.tubesandmore.com

Thomas

It is amazing that they can make such fine stuff, hey? Every now and then I decide to work on my Bulova watch when it gets out of alignment (hairspring, jewel, some dirt, etc.). Then I cross my eyes and say "forget it!" Don't know how they do that stuff....especially make wire that is so fine and so uniform.

Thomas

Yes, the same thing I think when I saw that.
Well lets see if tubesandmore.com have it.
Thanks to all.
Milton

:It is amazing that they can make such fine stuff, hey? Every now and then I decide to work on my Bulova watch when it gets out of alignment (hairspring, jewel, some dirt, etc.). Then I cross my eyes and say "forget it!" Don't know how they do that stuff....especially make wire that is so fine and so uniform.
:
:Thomas

Milton,
Take a close look at the original coil, and you may notice a special winding technique. A normal solenoid wound coil has concentric turns layed side by side, and in some cases, several layers (one atop the other)to attain the required inductance in a given space. Your oscillator coil may have the individual turns spaced farther apart, wound at an angle to axis of the core, with each successive layer reversing the angle. This technique is practically impossible to reproduce manually by hand, but lowers the inherent turn/turn and layer/layer capacitance noted in my earlier email. There may be some small manual coil winding machines still available, that can perform this task. I had one back in the 60's, but don't remember the mfr or vendor.
Melted parafin or bee's wax will aid in in placement and retention of turns/layers in place, without affecting the coil.
marv

:Yes, the same thing I think when I saw that.
:Well lets see if tubesandmore.com have it.
:Thanks to all.
:Milton
:
::It is amazing that they can make such fine stuff, hey? Every now and then I decide to work on my Bulova watch when it gets out of alignment (hairspring, jewel, some dirt, etc.). Then I cross my eyes and say "forget it!" Don't know how they do that stuff....especially make wire that is so fine and so uniform.
::
::Thomas

There's some curiosity. Sams Photofact says that this coils have 7 ohm resistance but I measure it and gave me 46 ohm. ¿whats happening here?
I've noticed that technique and is very hard to do at hand.

Milton

:Milton,
:Take a close look at the original coil, and you may notice a special winding technique. A normal solenoid wound coil has concentric turns layed side by side, and in some cases, several layers (one atop the other)to attain the required inductance in a given space. Your oscillator coil may have the individual turns spaced farther apart, wound at an angle to axis of the core, with each successive layer reversing the angle. This technique is practically impossible to reproduce manually by hand, but lowers the inherent turn/turn and layer/layer capacitance noted in my earlier email. There may be some small manual coil winding machines still available, that can perform this task. I had one back in the 60's, but don't remember the mfr or vendor.
:Melted parafin or bee's wax will aid in in placement and retention of turns/layers in place, without affecting the coil.
:marv
:
::Yes, the same thing I think when I saw that.
::Well lets see if tubesandmore.com have it.
::Thanks to all.
::Milton
::
:::It is amazing that they can make such fine stuff, hey? Every now and then I decide to work on my Bulova watch when it gets out of alignment (hairspring, jewel, some dirt, etc.). Then I cross my eyes and say "forget it!" Don't know how they do that stuff....especially make wire that is so fine and so uniform.
:::
:::Thomas

Milton,
If your measurement technique is accurate, the 46 vs 7 ohm difference is a large error. I suggest this may not be the original coil, but was replaced by a radio technician of yesteryear. It may have had the same visual appearance, but quite different electrically, and the technician was a pure amateur. On Riders 15-9, #5 under Alignment, it notes that filter capacitor metal can as the common negative reference ground for RF/IF tests, and hopefully not B-. You could disconnect the B+ feed at the bottom of each IF transformer (50/51) to verify that there are no high impedamce shorts or solder blobs inside their cans. Also note on Riders 20-15 that later production models had the tuning and trimmer capacitors connected to the chassis instead of the AVC line. If any of the production modifications noted in Riders were/are not installed correctly or incomplete, performance will be sacrificed. If you have the early production version, it should be like the schematic on Riders 15-8, otherwise all changes noted in Riders should be installed correctly.
marv

:There's some curiosity. Sams Photofact says that this coils have 7 ohm resistance but I measure it and gave me 46 ohm. ¿whats happening here?
:I've noticed that technique and is very hard to do at hand.
:
:Milton
:
::Milton,
::Take a close look at the original coil, and you may notice a special winding technique. A normal solenoid wound coil has concentric turns layed side by side, and in some cases, several layers (one atop the other)to attain the required inductance in a given space. Your oscillator coil may have the individual turns spaced farther apart, wound at an angle to axis of the core, with each successive layer reversing the angle. This technique is practically impossible to reproduce manually by hand, but lowers the inherent turn/turn and layer/layer capacitance noted in my earlier email. There may be some small manual coil winding machines still available, that can perform this task. I had one back in the 60's, but don't remember the mfr or vendor.
::Melted parafin or bee's wax will aid in in placement and retention of turns/layers in place, without affecting the coil.
::marv
::
:::Yes, the same thing I think when I saw that.
:::Well lets see if tubesandmore.com have it.
:::Thanks to all.
:::Milton
:::
::::It is amazing that they can make such fine stuff, hey? Every now and then I decide to work on my Bulova watch when it gets out of alignment (hairspring, jewel, some dirt, etc.). Then I cross my eyes and say "forget it!" Don't know how they do that stuff....especially make wire that is so fine and so uniform.
::::
::::Thomas