Patent US2221398A successfully refreshed from Google Patents.
US2221398A
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US
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Amplifier
Assignee: Allen B du Mont Laboratories Inc
•
Filing: 1939-09-08
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Granted: 1940-11-12
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Expires: 1959-09-08
Abstract
No abstract record available.
Inventors
- 👤 William A Geohegan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 23:50
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/26; H03F3/28; H03F3/02
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1943-11-12 | 1944-05-13 | 1944-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1947-11-12 | 1948-05-13 | 1948-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1951-11-12 | 1952-05-13 | 1952-11-12 | $7700.00 | Window Closed / Lapsed |