1A3
1A3 is also designated DA90. Completed sales put the typical price at $132.95 per tube.
Description
The 1A3 is a monoplate diode with an indirectly heated cathode, intended for use as an R.F. detector. It is designed for parallel filament supply and is also known as the DA90, a battery diode for signal detection.
Construction
The tube uses an A19-2 bulb and a 7C10 base. The DA90 designation specifies a miniature base. The mounting position is arbitrary.
Ratings
The filament requires 1.4 V at 150 mA (0.15 A). Interelectrode capacitances are: anode-to-cathode 0.4 pF, anode-to-filament 0.8 pF, and cathode-to-filament 0.6 pF. The resonant frequency is approximately 1000 Mc/s.
| Designation | Evidence | Confidence |
|---|---|---|
| DA90 | 45 independent documents | confirmed |
Equivalence is asserted only where the archive's own literature states it directly, in at least 40 separate documents. Tubes that merely substitute in some circuits are not listed here.
| Measure | Per tube |
|---|---|
| Median | $132.95 |
| Typical range (25th–75th) | $104.95 – $179.47 |
| Most sales (10th–90th) | $24.59 – $344.50 |
| Extremes incl. outliers | $24.59 – $344.50 |
| Completed sales | 9 |
| Brand | Median | Range | Sales |
|---|---|---|---|
| RCA | $104.95 | $92.50 – $179.47 | 3 |
| Condition | Median | Sales |
|---|---|---|
| NOS | $133.97 | 4 |
| used | $110.20 | 4 |
Per-tube prices from completed sales, 2026-07-09 to 2026-08-22. Matched pairs and quads are divided out. See the price index for how these move over time.
Original manufacturer datasheets for 1A3, hosted by Frank Philipse's Electron Tube Data sheets.
| Manufacturer | Designation | Datasheet |
|---|---|---|
| Mazda-Belvu | 1A3 | PDF (77 KB) |
| Tung-Sol | 1A3 | PDF (71 KB) |
| Telefunken | 1A3 | PDF (62 KB) |
| RCA (HB3) | 1A3 | PDF (40 KB) |
| Philips | DA90 | PDF (81 KB) |
| Mullard | DA90 | PDF (61 KB) |
Documents held here and used to write this page.
- DIODE MONOPLAQUE
- DA90 (filed under DA90)