Note
QST, Jul 1940, pp. 2–8.
QST, Nov 1941, p. 105.
Lafayette catalog number 82, p. 115.
QST, Apr 1943, p. 2.
Radio Craft, Nov 1944, p. 68. (ad -- "the radio that never slept")
QST, Apr 1945, p. 1 (reference to SX-28A)
When people think about a Hallicrafters receiver, the SX-28 may be what comes to mind. It is one of Hallicrafters' most popular and iconic products. Introduced in the summer of 1940 and sold through WWII with the last units made in 1946.
The Hallicrafters SX-28 Super Skyrider is a legendary pre-World War II shortwave communications receiver introduced in 1940. Regarded as a design that "put it all together," it combined the technical advancements of the 1930s into a single high-performance package. It became a heavily utilized "work-horse" for the U.S. military and Allied forces during WWII.
Outwardly, at least on the front panel, all of the SX-28 versions are identical. The SX-28A includes a rear panel AC line fuse. The main differences between the 28 and the 28A/28-FCC are in the design if the RF section. Specifically, the sensitivity and selectivity have been improved with the use of what the company called "micro-set" permeability-tuned inductors. The inductors, trimmers, and associated components for each RF stage are mounted on small, individual sub-chassis, easily removed for servicing.
Not to be confused with the visually identical SX-32.
The receiver was available with three optional speakers; the tabletop R-12-T, the gigantic free-standing console R-12, and the not-quite-as-gigantic R-8, as shown in the July 1940 issue of QST.
The SX-28 was highly advanced for its era, offering comprehensive frequency coverage and robust audio capabilities:
– Features six switched bands spanning from 550 Kc to 40 Mc.
– Includes directly calibrated main tuning and dedicated amateur bandspread on back-lit dials.
– Uses a high-performance superheterodyne design featuring two RF stages and two IF amplifiers.
– Offers three settings of crystal filter selectivity alongside three variable IF bandwidth settings.
– Equipped with a James Lamb IF noise blanker circuit capable of cutting through heavy pulse noise.
– Features an 8-watt, push-pull, high-fidelity 6V6 audio circuit with a tone control and bass boost.
– Features a built-in power supply, a major convenience compared to contemporaries requiring external power packs.
– Uses 500-ohm and 5000-ohm outputs, with the 5000-ohm line matching its companion PM-23 speaker.
Standard models featured aluminum side-louvers and a black, simulated-leather ("leatherette") front panel, though some rare variants featured a smooth, dark gray panel.
An estimated 50,000 units of the SX-28 and its variants were manufactured. Notable versions include:
– Original SX-28 (1940): The initial commercial production run, originally priced at $159.50.
– SX-28A (1944–1946): Electrically identical to the original but features a redesigned RF front-end sub-chassis to make component servicing easier. It can be identified by an external fuse holder on the rear apron and solid webbing between its tuning knob spokes. Wartime inflation brought its price up to $238.
– AN/GRR-2: The U.S. Military designation for the SX-28, which came equipped with a rugged, potted power transformer for wartime operations.
– Lend-Lease Units: A large number of units were shipped to Russia under the Lend-Lease Act, where they were commonly modified to utilize Russian vacuum tubes.
– SX-28FCC: A rare, specialized model manufactured explicitly for the Federal Communications Commission.
Specifications
Coverage: 540 kHz to 43 MHz
IF: 455 kHz
BFO
ANL: three-stage Lamb-type
S-meter
No internal speaker (500 or 5000Ω terminals are provided)
Audio output: 8 watts
Bass boost switch
Main tuning dial lock
Crystal filter
Variable IF selectivity (six steps from 12 kHz to CW)
Audio output: 8 watts, 500/5000 Ω
Power: 120 VAC, 120 watts, or 240 VAC with optional universal transformer, or 6 VDC with optional "vibrapack"
Tubes (15 total): (1) 5Z3, (2) 6V6, (1) 6SC7, (1) 6J5, (1) 6H6, (2) 6AB7, (2) 6B8 (2) 6SK7, (1) 6L7, (2) 6SA7
References
Recording War News with the SX-28. Radio News, Feb 1943, p. 18.
Updating. CQ, May 1959, p. 48.
