I have been very lucky that I could purchase a Zellweger E-646 receiver a few years ago. I felt even more lucky, when I found out, that production examples of this receiver had a different appearence - this was when the Swiss Army faded out quite a number of their of their E-646 receivers in 2007.

My E-646 prototype comes in two parts, one is the receiver section and the second is a mains power supply combined with a 24 V acumulator with internal charging circuit.
Both units have dimensions of 33 x 12 x 32 cm and are quite havy, a removable front cover protects from inpact on the controls durings transports.

The receiver section is very similar to the one found with production samples, the frequency is selected by means of decadic knobs between 2'000 and 11'999 kHz. The receiver comes with modes AM/A3 and single sideband A3JU (for lower sideband) and A3JO (for upper sideband, oberes Seitenband is written with a letter O in German), it seems as the set has an automatic ECSS feature. When switching to single sideband on a AM channel, You hear a slight hiss or weeze disappearing quickly, it sounds like if the BFO locks automatically on an AM signal's carrier.

Unfortunately, I have no access to the original development plans and schematic of this set, so I have no knowledge about the circuitry inside the receiver.

© Martin Bösch 26.11.1999 / 13.2.2007 / transl. 4.9.2010