What do you see in the FTPU image?

[darkspeed]

The upper and lower steel bailing wires look like "cut to length" signal delay lines.

1ns per foot.

Establishes the delay or phase between signals entering the real coil which is wound around the center of the spool.

[dankie]

theres nothing for you to see unless your name you are sweet , tesla or SM .

who here knows about radio or eletronics or anything related to be able to see ?

[Grumpy]

The upper and lower steel bailing wires look like "cut to length" signal delay lines.

1ns per foot.

Establishes the delay or phase between signals entering the real coil which is wound around the center of the spool.

Perhaps SM had to get the steel wire away from the real coil wrapped around the center of the spool.  Thank you for this keen observation.

I don't see any means of feedback via a field or space effect in this early version.  This unit may have no feedback at all.  The output was pretty low compared to later units.

Anyone see a collector coil or wire in this unit?

[sparks]

at about 4 oclock on the lower disc I believe it is a relay coil.  This could have been duplicated in the top disc with a shaded area about the same dimension as the bottom relay coil.  The white thing in the middle appears to be a spool of wire as you can see the turns through what appears to be mylar tape wrapped around the coil.  The bailing wire and loop windings appear to go through the center of the relay coils.  This would alter the core parmaeters of the relay coils and the output voltage is simply induced by any magnetic field changes in the bailing wire and copper coils. The white spool of wire is again wrapped with a solenoidal wire on a portion of the spool and this appears again to be a highimpedance coil.  There also appears to be a few number of turns wrapped around this unit of the white lead wires leading out of the spool. Looks abit like a torroidal hf transformer with a copper coil forming the core material.  Any current through the core coil would appear to the transformer as a magnetic saturation of the core.  Unlike a saturable core reactor the core saturation is controlled by an active element not relying on a winding on the outside of the torroid to effect the magnetic field inside the windings.

[giantkiller]

Any current through the core coil would appear to the transformer as a magnetic saturation of the core. 
*Unlike a saturable core reactor the core saturation is controlled by an active element not relying on a winding on the outside of the torroid to effect the magnetic field inside the windings.

This is the final clue! The GK4 exhibited this on a very dynamic and spaztic level. And this looks just like Otto's windings.

--giantkiller.