The GenRad 1491-G Decade Inductance Box is the most accurate decade inductor commercially available. The 1491, has a max inductance of 11 H and a
resolution of 100 µH.
The decade switch has high-quality
ceramic stator and-rotor members and well-defined ball-and-socket detents. All
contacts are made of a silver alloy and have positive wiping action. Shielded
toroidal cores are used for small mutual inductance and minimum effect from
external fields.
The 1491-G decade inductors are convenient
elements for use in wave filters, equalizers, and turned circuits throughout the
range of audio and low radio frequencies. As components in oscillators,
analyzers, and similar equipment, they are especially useful during the
preliminary design period, when the ability to vary circuit elements over
relatively wide ranges is necessary to determine optimum operating values. The 1491-G Decade Inductors have values of low-frequency storage factor, Q, that are
much larger than those of air-core coils.
GenRad 1491 Decade Inductor Basic Specifications (Full specifications can be found on datasheet)
Range:
1491D Decade inductor, 4 decades, 11.11 H total inductance, 1 mH per step
1491G - Decade inductor, 5 decades, 11.111 H total inductance, 100 µH per step
Accuracy (Low Frequency, Low Signal Level):
| Model |
100 µH |
1 mH |
10 mH |
100 mH |
1 H |
| 1491-D |
N/A |
2% |
1.6% |
0.8% |
0.8% |
| 1491-G |
2% |
2% |
1.6% |
0.8% |
0.8% |
Frequency Characteristics:
Percentage increase in effective series inductance (above the
zero-frequency value, Lo) may be obtained by interpolation in accompanying graph
(see Figure 2 on datasheet or in manual) for any setting to the highest-value
decade used, when LOW terminal is grounded to cabinet.
Zero
Inductance: Approximately 1 μH
Maximum Voltage:
500V rms. Switch will break circuit at 500V if turned rapidly, but voltages
above 150V may cause destructive arcing with switch between detent
positions.