Note
QST, Nov 1960, p. 1.
QST, Dec 1960, p. 189. (specs)
QST, Jan 1964, p. 173.
QST, Mar 1965 p. 103.
The SX-140 receiver was part of the “Halli-Kit” AM/CW station, together with the HT-40 transmitter.
The Hallicrafters SX-140 (also offered in kit form as the SX-140K) is a compact amateur-band communications receiver designed to cover six amateur bands from 80 through 6 meters.
The receiver operates across a continuous range of 3.5 MHz to 54 MHz, specifically covering the 80, 40, 20, 15, 10, and 6 meter ham bands on an easy-to-read slide-rule dial driven by a single main tuning control. It utilizes a superheterodyne circuit powered by five vacuum tubes and two silicon rectifiers, consuming 47 watts.
The intermediate frequency is set to 1650 kHz. On the 80, 40, and 20 meter bands, the local oscillator operates above the incoming signal frequency. On 15 and 10 meters, it utilizes the oscillator's second harmonic operating above the signal, while on the 6 meter band, it uses the second harmonic operating below the signal. On several bands, the tuning range extends slightly past the standard FCC band limits to allow reception of auxiliary or special service frequencies.
The receiver accommodates AM, SSB (upper and lower sideband), and CW reception. Selectivity and sensitivity are enhanced by a regenerative IF stage. The SELECTIVITY-BFO control offers continuously variable selectivity for AM signals up to the point of BFO engagement. Past that point, the circuit enables CW and SSB demodulation, allowing the operator to adjust the pitch of CW signals.
A front-panel Carrier Level meter serves as an S-meter for signal strength evaluation and precise tuning. The SX-140 also includes a built-in crystal oscillator circuit. Inserting a 3.5 MHz crystal allows setting the low-frequency band edges on 80 through 10 meters and 52.5 MHz on 6 meters. Plugging an optional 1650 kHz crystal into the calibrator socket allows aligning the IF transformers directly using the Carrier Level meter as an output indicator.
When set to STANDBY, auxiliary switching controls an external antenna changeover relay, muting/shorting the speaker voice coil, or keying a transmitter.
Here are the technical specifications and receiver frequency coverage for the Hallicrafters SX-140K, copied directly from Section II of the manual:
Specifications
– Headphone Output: Low to medium impedance
– Antenna Input: Single wire or any 50–75 ohms, unbalanced
– Audio Output Impedance: 3.2 ohms
– Intermediate Frequency: 1650 KC
Frequency Coverage
80 m: 3.5–4.0 MHz
40 m: 7.0–7.3 MHz
20 m: 14.0–14.4 MHz
15 m: 21.0–21.5 MHz
10 m: 28.0–29.9 MHz
6 m: 50.0–54.0 MHz
Tube Linuep (5 total)
6AZ8 RF amp / calibration osc
6U8A Local osc / mixer
6BA6 IF amp
6T8A detector / ANL / 1st audio amp
6AW8A audio output / S-meter amp
Power requirements: 115 VAC, 50/60 Hz, 47 watts.
References
Review. 73, Nov 1963, p. 62
More gain. 73, Mar 1964, p. 54.
