Identify 1920s German coil mounts?

These have no maker's name and no other markings except the knob engraved "Kopplung" and the number of turns stamped into the clamps of the plug-in coils.  Does anyone recognize the manufacturer, or the date?  Also I am missing the smaller knob that positions the rear coil; does anyone know what it looked like?   

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Dear Alan,

please go to ID182762 and ID106033 and compare with "Huth Spulenkopppler"

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Dear Alan,

Sorry, I had made an erroneous allocation. (Nobody is perfect...)
Now I know better, that not Huth made such Variable Couplers, but it was Vogel (Ledion).

Corrections are made now, see here and here.

But these are not exactly similar with Yours.

Regards,
KoBi

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We're getting closer.  All I can find for Vogel are some ads in Radio (Berlin) from 25 February and 10 October 1926.  They look promising, but the coils aren't quite the same, and unfortunately the ads don't show photographs.

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Would these have been used on breadboards, exposed on the top of a cabinet, or inside cabinets?  Does anyone have photos of actual  radios using them, or magazine articles, or book illustrations? 

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Vogel / Ledion did not make radios, and the products were aiming for the amateur market, there would hardly be a manufactured radio using these couplers. I came never across of a fabricated model using such Ledion spindle couplers

With other manufacturers it is different. Huth used their couplers for the regular radio models and offered the sole couplers as well for sale.

The couplers in question are called "Aufbaukoppler" (surface mounted), mainly for external application to ease coil change, but also inside of a cabinet mounted to the baseplate.

Another type is called "Einbaukoppler" to be fixed inside to the front panel.

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Now to Your couplers: If ound in a catalog a drawing, very similar in shape and knob. Only the spindle is reversed.

It is obviously the own-brand of Prohaska, a poular pre-war mail order house.
See # 828, p.161 in the Prohaska Katalog 1928: Low-Loss-Parallelkoppler.

• Prohaska_Low-Loss-Parallelkoppler (71 KB)

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Thank you; that's very helpful.  The 828b model also shows the knob I'm missing. 

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