Note
The SB-313 is the solid state replacement for the SB-310 SWL receiver. Just as the SB-310 is a copy of the SB-301, so too the SB-313 is essentially a copy of the SB-303. It is curious, then, that Heath waited a full two years after the release of the 303 to introduce the 313.
The 313’s frequency coverage is the same as the SB-310’s except that the 26.9 to 27.4 MHz band of the 310 has been replaced with the 21.3 to 21.8 MHz band.
Frequency coverage includes 3.5 to 4.0; 5.7 to 6.2; 7.0 to 7.5; 9.5 to 10.0; 11.5 to 12.0; 14.0 to 14.5; 15 to 15.5; 17.5 to 18.0; and 21.3 to 21.8 MHz. These frequencies translate to the 15, 16, 19, 25, 31, 41, and 49 meter international broadcast bands and the 20, 40, and 80 meter ham bands.
There are some obvious differences between the 313 and the 303. For example, the SB-313 requires no provisions for external VHF converters. Deletion of the converter selector from the front panel makes room for a headphone jack (found on the rear panel of the SB-303). Also, the SB-313 has no RTTY board, and the RF mixer board requires fewer installed parts as a result. And the 313 has a much simpler rear panel. There are only four RCA jacks on the rear panel—antenna input, 8Ω speaker output, mute, and a spare. Among the items missing from the rear panel are all the outputs needed for use with the SB-650 digital frequency display, though these could be added by the user.
The SB-313 is a very good receiver but its price tag may have been a little steep for all but the most hard-core of shortwave listeners. It was popular enough to maintain a place in the catalog until 1976, but it never sold very well. The SB-313 has always been scarce and because of its similarity to the SB-303, they are easily overlooked at swaps.
Refer to SB-303 for additional discussion.
Refer to SB-100 for a discussion of crystal filter options.
References:
Brief description. Popular Electronics, Nov 1972, p. 32.
Increase friction in worn zero set. QST. Jan 1973, p. 52.
Zero set dial modification. QST. Feb 1980, p. 44.
Frequency range (MHz): 3.5 to 4.0; 5.7 to 6.2; 7.0 to 7.5; 9.5 to 10.0; 11.5 to 12.0; 14.0 to 14.5; 15 to 15.5; 17.5 to 18.0; and 21.3 to 21.8 MHz
IF: 3395 kHz
Frequency stability: less than 100 Hz drift after 10 minute warmup. Less that 100 Hz drift for ±10% change in line voltage
Frequency selection: built-in LMO
Modes: USB, LSB, CW, AM
Sensitivity: less than 0.5 µV for 10 db signal-plus-noise to noise ratio for SSB
Overall gain: less than 1.5 µV input for 0.5 watts audio output on the 3.5, 5.7, 7.0, 14.0, 15.0, 17.5 and 21.3 MHz bands. Less than 3.0 µV for 0.5 watts audio output on the 9.5 and 11.5 MHz bands.
AGC characteristics:
blocking: greater than 3.0 V CW/SSB
dynamic range: greater than 150 db CW/SSB
RF attenuator range: 40 db
Selectivity:
AM: 5.0 kHz at 6 db down, 15 kHz maximum at 60 db down
SSB: 2.1 kHz at 6 db down, 5.0 kHz maximum at 60 db down
CW: 400 Hz at 6 db down, 2.0 kHz maximum at 60 db down
Image rejection: 60 db or better
IF rejection:
3.395 MHz: greater than 55 db
8.595 MHz: greater than 40 db
Spurious response: all below 1.0 µV equivalent except at 10.0 and 15.375 MHz
Operating temperature range: 10 to 50 C
Visual dial accuracy: within 200 Hz on all bands
Electrical dial accuracy: within 400 Hz on all bands after calibration to nearest 100 kHz or 25 kHz point
Dial backlash: less than 50 Hz
Calibration: every 100 kHz or 25 kHz
Antenna impedance: 50Ω nominal, unbalanced
Audio response:
AM: 200 to 4750 Hz nominal at 6 db (with supplied filter)
SSB: 350 to 2450 Hz nominal at 6 db (with optional filter)
CW: 800 to 1200 Hz nominal at 6 db (with optional filter)
Audio output impedance:
speaker: 8Ω
headphones: low impedance
Audio output power: 4 watts at less than 10% distortion
Muting: open external ground at mute jack
Power requirements: 120/240 VAC, 50/60 Hz, 40 watts maximum
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.
