National SW-3
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| Frequency | RX: ~0.09–35 MHz (plug-in coils) |
| Bands | ~90 kHz-35 MHz via coils (LF-10m) |
| Power | Receiver only |
| Modes | AM, CW |
| Weight | 4.5 kg (9.9 lb) |
| Connector | binding-posts |
| Year | 1931 |
| antenna | binding-posts |
Estimated (unverified): Weight ~4.5 kg (about 10 lb) for the receiver is approximate and not stated on a primary spec sheet (it uses a separate power supply). Antenna connection is via binding posts/terminals (era-typical).
One of the most popular shortwave receivers of the early 1930s - a compact three-tube regenerative set designed by National's James Millen as a budget companion to the SW-5. Plug-in coils cover roughly 90 kHz to 35 MHz, with the original three coil sets giving good bandspread on the 80, 40 and 20 meter ham bands. Smooth regeneration and National's solid mechanical build made it a favorite.
It is a regenerative receiver, so selectivity is only what the regeneration control provides, and each plug-in coil covers a limited range. It is headphone-only unless an outboard amplifier is added. Regenerative sets were soon eclipsed by the superheterodyne.
The SW-3 helped build National's reputation with amateurs in the early 1930s and became the company's most popular regenerative receiver, made from 1931 into the 1940s. Designed by James Millen - who would go on to lead development of National's superheterodyne HRO - it is a charming, hands-on set that remains a collector favorite and a fine introduction to the regenerative era.
The National SW-3, affectionately known as the 'Thrill Box,' is one of the most beloved early shortwave receivers - a compact, three-tube regenerative set from 1931 that introduced a generation of listeners to the thrill of pulling distant signals from the ether. It uses interchangeable plug-in coils to cover a wide span (roughly 90 kHz to 35 MHz with the various coil sets) and is a headphone-only design, with a regenerative detector that the operator brings just to the edge of oscillation for maximum sensitivity.
Designed by National's James Millen as a budget, headphone-only companion to the costlier SW-5, the SW-3 was simple, inexpensive and surprisingly capable for its size. It was enormously popular and remains a quintessential example of the regenerative era, when skill at coaxing the regeneration control was part of the art of listening. Its compact size, glowing tubes and hands-on tuning make it a perennial favorite among collectors.
It is a discontinued classic. See the superheterodyne AGS-X and the later HRO.