Hammond "Classic" 300 series, power transformers



The 370HX is the power transformer for a 2A3 SE (mono/stereo) or a 2A3 PP (mono) amplifier. Problem is that there are no (extra) filament winding(s) for the directly heated output tubes. This problem is easily solved by using one of the small Hammond 266 transformers. A 2A3 SE can be made quiet enough with AC tension on the filament. When you build a mono bloc 2A3 SE use a Hammond 266M2. When you build a stereo 2A3 SE (or a mono 2A3 PP) use the Hammond 266M5. The 266M5 has 2 windings of 2,5V/3A each.

The 374BX is the standard power transformer for a 300B SE (mono/stereo) or a 300B PP (mono) amplifier. To solve the problem of the missing filament windings use a Hammond 266M12. With a 300B it is almost always necessary to use a 5V DC filament power supply.
A 6,3VAC winding, bridge rectifier, capacitor of 10.000uF and a small low value resistor to tune the tension to exactly 5 VDC is the cheapest solution. For best sound quality use the 6,3V AC winding into Tentlabs DHT Filament module.





Key Features:

• Primary: Universal - 100, 110, 120, 200, 220, 240 VAC 50/60 Hz.
• Units are designed to operate with BOTH primary windings engaged.
• Bias Tap: 50 VAC tap from high voltage secondary C.T.
• Highpot tested: 2,000 VAC
• Faraday Copper Primary Shield: Our electrostatic shield reduces the capacitive coupling from the primary - greatly attenuating higher frequency current coupling to the secondaries (shield is internally grounded to the end bell).
• Windings: Concentric wound for low stray field and low noise.
• This series is an upgrade from the "200" SERIES range of units
• 2 models designed specifically for 300B tubes (300BX) and 2A3 tubes (302AX).
• Finish: Black powder paint to match our 1650 series of output transformers
• Units can be run full wave bridge or full wave C.T.
• Conservative designs - CSA certified (209651).