SE-415 (Zellweger, Switzerland) 1kW 2-52MHz Transceiver

This big and heavy ISB radio was used mobile in a truck and in fixed in command posts providing encrypted teletype communications on higher army echelons. Voice was available, but as it was unencrypted, it was not actually used. The development and trials took a long time, see an advertisement from 1964 using the MOWAG van. After commissioning in 1970 - a STEYR truck was now used - a major overhaul and modification program was undertaken in 1974. The radios were retired in 1987, replaced by the SE-430.

My Station

The radio was used at my amateur station and several times mobile for the "Jamboree on the air JOTA" on SSB. Some "improvements" were needed for amateur use and these are described below. Take a look at pictures of the mobile setup, taken ~1995 with an early digital camera! The internal view shows the station rack (the second HFO is out), left top the manual vertical ATU, right center the E863/KW2 receiver. The external view of the modified Land Rover 107 Station Wagon shows the mast (6m) for the TH3JR dipole and the base for the vertical on the roof. The view of the operator's position shows the receiver with audio DSP on top, speakers and microphones, log, top right a lamp, the wire dipole ATU remote control and the TH3JR rotator control next to the receiver.

SE-415, Transmitter, Receiver, Operator, Power

Amateur Radio Modifications and Upgrades

The following upgrades/modifications described are reversible as no mechanical changes are necessary.

Upgrade for efficient CW Operation

As issued the SE-415 has CW settings but the actual operation is not really useful in amateur radio service. The reasons for this deficiency and a solution are described in detail in the presented document. The document includes marked-up circuit diagrams and board layouts and the upgrade can be implemented along those lines. A Field Day contest has successfully been worked by experienced CW operators in 2002 with a SE-415 thus modified.

Modification to be able to use USB and LSB for Voice (+Data)

The SE-415 has been designed as a true ISB radio but with fixed allocations of services to sidebands (voice on LSB, 2x RTTY and pilot on USB). The modification implements the switching of the voice channel to either SSB filter in transmit and receive modes. The proprietary RTTY channels and the pilot signal are no longer available. Amateur radio RTTY can be implmented using e.g. a soundcard and a PC program or a modem through the voice channel. Digital modes that rely on fast receive-transmit changeovers such as AMTOR or PSK31 cannot be implemented with the SE-415, it is far to slow.

The described modification has been used in my home station for many years and been implemented on two SE-415 and additional modules. The document describes the necessary changes in detail but at this time no marked-up diagrams are included.