the Hallicrafters Co., Chicago
SX - 42
überarbeitet am 19.10.2010
As a successor of the venerable SX-28,
a prewar construction, 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 not only with coil but also crystal filters. It was the receiver
with the most extended band coverage available in the early fifties.
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 SX-42 comes only with a 110 V mains transformer for U.S. use, Hallicrafters offered a multi voltage transformer for international users. You can connect a high impedance speaker to the speaker output sockets, the original matching speaker 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, similar to the one found at the SX-28. 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.
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.
As my SX-42 is misaligned, I cannot give correct informations about the behaviour
of an optimally aligned set. In the AM bands, the sensitivity is what You would
expect from the single conversion design, selectivity with the LC filters
activated is not sufficient to separate two channels with 5 kHz spacing. In
CW operation, the crystal filters give good separation and You can "phase out"
infering signals with careful use of the CRYSTAL PHASING control.