Hallicrafters SX-23
The Hallicrafters Co., Chicago, IL

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-611 / Hallicrafters SX-23
E-625 / National HRO7
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
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überarbeitet am 1.6.2013

The receiver Hallicrafters SX-23 with it's outstanding art deco design seems to have seen use with the Swiss Army, the purpose of use is unknown to me.

Single conversion heterodyne, ZF 455 kHz

Analog dial

540 kHz - 34 MHz, bandspread within 80 - 10 m ham bands

AM, CW with BFO



RF-Gain, band spraead, crystal phasing notch filter

The SX-23 has a 48 x 23,5 x 31,8 cm metal cabinet, it's hinged lid gives access to the chassis for valve replacement.

The Super Skyrider SX-23 has a quite unique art deco cabinet not seen with any other Hallicrafters sets. In contrast to earlier receivers made by Hallicrafters, it does not come with a engraved metal disk dial mounted in front of the front panel but with a metal dial rotating behind a sector shaped dial window, two smaller windows show a mechanical band indicator and the signal strength meter. In contrast to later models, the dial is not of the transparent backlit type. Below the main frequency dial, you find the the band selector with markings for the four ham bands and four "General coverage" bands: 540 kHz - 1,7 MHz, 1,7 - 5,2 MHz, 5,2 - 16,5 and 16,5 - 34 MHz. The "steering wheel" main tuning knob is replaced by one with a fine tuning gear in my example of the receiver. I logging dial and calibration chart can be use to re-tune a known frequency in the bandspread frequency bands.
The BFO control is located at the left of the main frequency dial window, below the tone control, combined with the mains on/off switch as found typically in most older Hallicrafters equipment. The AF Gain / volume control and the RF gain controls reside next to it. Underneath, you find the switches for the noise limiter and receive /transmit switch to be used when operated together with a matching transmitter. In the right lower corner of the front panel, you find the bandwidth control which is combined with the A.V.C., the automatic volume control. With the A.V.C. off, a narrow crystal filter for CW reception and a slightly wider for telephony reception is selectable, with A.V.C. activated, the crystal filter fo telephony and a narrow and wide LC filter are switchable.

The RF signal coming from the antenna input is amplified in a RF amplifier stage (6SK7) and fed to the mixer stage (6SA7) to generate an intermediate frequency of 455 kHz; a 6SJ7 valve ist used in the local oscillator. After two IF amplifier stages (6SK7, 6SK7), the signal is demodulated (6SQ7) and fed to the audio preamplifier and final amplifier (6F6). The BFO (6SJ7) is used for CW and single side band signal reception. A 6B8 is used for A.V.C., the double diode 6H6 in the noise limiter. The eleventh valve is the two way rectifier valve 80.

There are no informations available about the purpose of use of the E-611 / Hallicrafters SX-23, it probably has been used for monitoring or signal's intelligence.

© Martin Bösch 1.5.2013