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 (mobile) Station
One radio was for many years used as my main transceiver in my shack and a second SE-415 was deployed several times mobile for the "Jamboree on the air JOTA" on SSB. Some "improvements" were needed for successful amateur use and these are described further below. The symmetrical ATU for the dipole 2-12MHz is covered on its own page - see the page link.
Take a look at pictures of the mobile setup, taken ~1995 with an early digital camera! The external view of the modified Land Rover 107 Station Wagon shows the mast (6m) for the TH3JR dipole and the base for the military vertical controlled by the manual ATU on the roof (just above the oblong roof window). 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 detailed 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 installed in my 107 series III Defender
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) - even as true duplex station on VHF frequencies. The modification implements the switching of the voice channel to either SSB filter in transmit and receive modes using existing modules and circuits. After the mod using only the existing wiring of the rack, the proprietary RTTY channels and the pilot signal are no longer available. Amateur radio TTY can be implmented using the voice channel. Digital modes that rely on fast receive-transmit switching times such as AMTOR or PSK31 cannot be implemented with the SE-415, the changeover is far to slow.
The described modification has implemented on two SE-415 and additional modules and used successfully for many years. The document describes the necessary changes in detail but at this time no marked-up diagrams are included.
