SX - 42

the Hallicrafters Co., Chicago

Swiss Army Communication Sets
Synoptic Table
Army Receiving Sets
Exxx Designations
E-600 / Autophon E39
E-601 / Zellweger E41
E-602 / Autophon E44
E-603 / Autophon E45
E-604 / Autophon E46
E-606 / Velectra
E-610 / National HRO
E-614 / Hallicrafters SX-42
E-625 / National HRO
E-626 / Zenith H500
E-627 / Autophon
E-628 / Autophon
E-629 / Collins 51J-4
E-635 / Philips BX-925A
E-638 / Telefunken E108
E-639 / Telefunken E104
E-640 / Telefunken E127
E-643 / Collins 51S-1
E-645 / Siemens E311
E-646 / Zellweger
E-649 / Watkins-J.
E-655 / Racal
E-657 / Telefunken
Equipment List
Army Manuals
varia / copyright
about / contact

überarbeitet am 2.1.2015

In a list off receivers that have been acquired in small numbers by the Swiss Army, you can also find different Hallicrafters radios.

Hallicrafters presented the SX-42 All Wave Receiver in 1947; the double conversion was the top of the range set of the first Hallicrafters post war receiver generation. According to the X in the model designation, it is equipped with crystal filters. The prototype of this receiver with the most extended band coverage available in the early fifties came with five bands and a coverage up to 55 MHz. When the FCC decided to move FM broadcasting not into the 2 m band, but in the 88 - 108 MHz range, the Hallicrafters engineering team decided to add a sixth frequency range up to 110 MHz, so that todays standard FM bradcast band was also covered.

Single conversion, IF 455 kHz, 10,7 MHz

Analog dial, separate band spread dial

AM, CW with BFO, FM (above 27 MHz)

AM: MW 4 uV, SW 0,75 uV

Selectivity 6 dB
13 kHz, 7 kHz, 6 kHz, Crystal filter 1,5 kHz - 50 Hz

RF Gain, Noise limiter,
Crystal phasing Filter

The SX-42 comes in an impressive dark grey metal cabinet, with it's dimensions of 508 x 260 x 406 mm, it weighs 23,6 kg. The SX-42 has a hinged lid cover giving access to the tube sockets as found in most older Hallicrafters sets. The standard U.S. SX-42 came only with a 110 V mains transformer, in Switzerland, usually the multi voltage transformer version was in use. The original matching high impedance speaker to be conected to the speaker output sockets is Hallicrafter's R - 42.

The front panel is dominated by the big semicircular bright green backlit frequency dial. The main dial is driven by the main tuning knob, it has markings for the broadcast and amateur radio shortwave bands and an additional 0 - 100 logging scale. The inner concentric part of the tuning knob operates the bandspread dial, this one also with a 0 - 100 scale. A huge rotary knob in the left lower corner of the front panel acts as band range switch, the markings on the edge of the knob are hard to read.

The mains switch / volume control is found just at the right of the main tuning knob, three switches above the headphones jack activate the AVC, the Noise Limiter and the sets the receiver to STANDBY or RECEPTION mode.
At the right, below the round signal strength meter, You find another six rotary controls in two rows.
In the bottom row, You find the SELECTIVITY switch to select one of the three coil or crystal filters. Next is the TONE switch with HIFI and BASS positions for high fidelity performance, and then the SENSITIVITY control, in fact a RF gain control.
In the top row, You find the control for the CRYSTAL PHASING filter, active in the crystal filter positions of the SELECTIVITY switch. In the middle, the RECEPTION mode switch, the position CW activates the BFO, adjust with PITCH CONTROL for zero beat in SSB transmissions or for optimal beat note.
A nice feature for the less technically minded are small red dots indicating the normal setting of all controls for AM reception and green dots for FM reception.

The RF signal coming from the antenna socket will pass two RF amplifier stages and then be mixed to the intermediate frequency of 455 kHz, in FM modes for the usual 10,7 MHz. After having passed the three coil filters or the crystal filter, the signal is amplified in three IF amplifier stages and handed over to the AM demodulator. A noise limiter mutes the audio signal during short signal peaks. The BFO signal is injected in the demodulator stage for CW and SSB reception. After an audio preamplifier, a push-pull final stage will pass on the audio signal to the speaker connectors. For low impedance speakers, you need a matching transformer integrated in the matching Hallicrafters speaker.

I do not have any informations about what kind of use, the E-614 / Hallicrafters SX-42 has seen with the Swiss army, it probably has been used for signal interception / spectrum surveillance purposes. The SX-62 as a successor to the SX-42, equipped with a linear frequency dial and same frequency coverage has also been used by the Swiss army in small numbers, itg carried the designation E-644.

further reading:
d / e: Hallicrafters SX-42 at www.radiomuseum.org
e: the SX - 42 and SX - 62 - two Hallicrafters favourites, John Bryant, James Goodwin, fine tuning proceedings
e: Dachis, Chuck: Radios by Hallicrafters, Schiffer Publishing Ltd, Atglen, PA 19310, USA

© Martin Boesch 2.1.2015