Hammond 1645A 30W 5K Ohm Push-Pull Output Transformer with 70V Tap
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Create Free Business AccountKey Features
- 30 W RMS push-pull, 5,000 ohm CT primary, 128 mA per side
- Secondary taps for 4, 8, 16 ohms plus 70V (ORN lead, per drawing)
- Suggested tubes: 6L6GC, 6V6, 807, 5881, EL34 (2 tubes)
- 40% screen taps for Ultra-Linear operation
- 30 Hz to 30 kHz at full rated power, +/- 1 dB max.
- Shielded case, 4 slot above chassis Type "X" mounting, 4.5 lbs
The 1645A is a 30 watt (RMS) push-pull output transformer whose drawing is titled "Tube Output (30 Watts) Easy Wire Secondary – Ultra Linear". Alongside the usual 4, 8 and 16 ohm taps, its secondary adds a 70V output on an orange lead, as shown on the drawing label and in the series ordering table (4-8-16-70V). The part page lists the secondary as 4-8-16.
The 5,000 ohm centre-tapped primary is rated at 128 mA DC per side. Suggested tube types are 6L6GC, 6V6, 807, 5881 and EL34 in push-pull (2 tubes), and the 40% screen taps allow Ultra-Linear operation if desired. Typical applications are triode, Ultra-Linear pentode, pentode and tetrode connected audio output.
Rated response is 30 Hz to 30 kHz at full rated power, +/- 1 dB max. (ref. 1 kHz). Typical drawing data: 167 ohms primary DCR, 10.6 H primary inductance, 65 kOhm primary impedance, 355.3 mH leakage inductance, 9.3 ohms Black–Orange DCR and 3.93 kOhm Black–Orange impedance, with 2000 Vrms dielectric strength and a -40 to 105 C range.
The 1645A uses an enclosed (shielded) case with 4 slot, above chassis Type "X" mounting, plastic coil forms and insulated 8" minimum leads. Dimensions are A 2.50 in, B 3.75 in, C 3.06 in, D 2.00 in and E 2.69 in, with 4.5 lbs weight. Made in Canada; RoHS and REACH compliant.
Ideal For
- 30 W push-pull EL34 or 6L6GC amplifiers
- Ultra-Linear pentode output stages
- Tube amplifiers feeding 70V speaker lines
- Triode or tetrode connected push-pull output
Mounting
| Mounting Style | 4 slot, above chassis Type "X" mounting |
| Mounting Slot G | 0.20 in (5 mm) x 0.38 in (10 mm) |
Overview
| Series | 1608A-1650A Series, Tube Output (10 - 280 Watts) Easy Wire Secondary, Push-Pull HI-FI |
| Typical Applications | Push-pull: triode, Ultra-Linear pentode, pentode and tetrode connected audio output |
| Manufacturer Description | Output transformer, push-pull, 30W , primary 5,000 ct, 128 ma., secondary 4-8-16 |
| Manufacturer Short Description | AUDIO TX 5K OHM 30 WATT |
Dimensions
| Dimension A | 2.50 in (64 mm) |
| Dimension B | 3.75 in (95 mm) |
| Dimension C | 3.06 in (78 mm) |
| Dimension D | 2.00 in (51 mm) |
| Dimension E (+/- 1/16") | 2.69 in (68 mm) |
Electrical
| Operation | Push-Pull (2 Tubes) |
| Screen Taps | 40% screen taps for Ultra-Linear operation (if desired) |
| Audio Power (RMS) | 30 W |
| Primary Impedance | 5,000 ct ohms |
| Maximum DC Per Side | 128 ma. |
| Suggested Tube Types | 6L6GC, 6V6, 807, 5881, EL34 |
| Rated Frequency Response | 30 Hz to 30 kHz at full rated power (+/- 1 dB max., ref. 1 kHz) minimum |
| Secondary Impedance (Part Page) | 4-8-16 ohms |
| Secondary Impedance (Series Table) | 4-8-16-70V ohms |
Identifiers
| UPC | 623980024271 |
| UNSPSC | 39121301 |
| Part Number | 1645A |
Packaging & Shipping
| Shipping Weight | 4.5 lbs (2.04 kg) |
| Unit Weight (Series Table) | 4.5 lbs |
Construction & Finish
| Leads | Insulated flexible leads, 8" min. |
| Enclosure | Enclosed (shielded) |
| Coil Forms | Plastic coil forms for coil support and insulation |
| Lead Colour Code | Primary: BLU (plate), BRN (plate), RED (B+), BLU/YEL and BRN/YEL (screen taps, 40% of primary volts); Secondary: BLK (COM), GRN (4 ohm), YEL (8 ohm), WHT (16 ohm), ORN (70V) |
Environmental & Protection
| Temperature Range | -40 to 105 C |
| Dielectric Strength | 2000 Vrms |
Compliance & Certifications
| RoHS Compliant | Yes |
| REACH Compliant | Yes |
| Country Of Origin | Made in Canada |
Electrical (Typical, Drawing)
| Output Power | 30 W |
| Input Impedance | 5000 ohms |
| Output Impedance | 4/8/16/70V ohms |
| Primary DCR (Blue–Brown) | 167 ohms |
| Frequency Response (Typical) | Typ. 1.0 dB from 30 Hz to 30 kHz |
| Secondary DCR (Black–Orange) | 9.3 ohms |
| Primary Inductance (Blue–Brown, @ 1.0 KHz, 1.0 V OC) | 10.6 H |
| Secondary Impedance (Black–Green, @ 1.0 KHz, 1.0 V OC) | 246 ohms |
| Secondary Impedance (Black–White, @ 1.0 KHz, 1.0 V OC) | 850 ohms |
| Secondary Impedance (Black–Yellow, @ 1.0 KHz, 1.0 V OC) | 461 ohms |
| Secondary Inductance (Black–Green, @ 1.0 KHz, 1.0 V OC) | 135.8 mH |
| Secondary Inductance (Black–White, @ 1.0 KHz, 1.0 V OC) | 322.6 mH |
| Secondary Inductance (Black–Orange, @ 1.0 KHz, 1.0 V OC) | 759.2 mH |
| Secondary Inductance (Black–Yellow, @ 1.0 KHz, 1.0 V OC) | 219.7 mH |
| Primary Leakage Inductance (Blue–Brown, @ 1.0 KHz, 1.0 V SC) | 355.3 mH |
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Frequently Asked Questions
Does the 1645A have a 70V output?▾
The drawing and series table show a 70V secondary tap on the orange (ORN) lead in addition to 4, 8 and 16 ohms; the part page lists the secondary as 4-8-16.
Which tubes are suggested?▾
6L6GC, 6V6, 807, 5881 and EL34 in push-pull (2 tubes).
What is the primary rating?▾
5,000 ohms centre-tapped with 128 mA maximum DC per side.
Can this transformer be used for Ultra-Linear operation?▾
Yes. It includes 40% screen taps (BLU/YEL and BRN/YEL leads) for Ultra-Linear operation if desired.
What are its dimensions?▾
A 2.50 in (64 mm), B 3.75 in (95 mm), C 3.06 in (78 mm), D 2.00 in (51 mm), E 2.69 in (68 mm); 4.5 lbs.
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