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Tube Heater Supply

TentLabs heater supply is designed to supply the heaters of indirectly heated tubes. Its' main use is feeding phono and linestage tubes, to keep the hum levels down. The module can also be applied to feed other circuits to, that require a similar voltage and current supply.

So for example say you have a line stage pre-amplifier that uses 2 x 12AX7s. These both receive 6.3Vac to their heaters in parallel. You can install the Tube Heater Supply here. Basically connect the 6.3Vac supply from the mains transformer to the "AC IN" on the board and wire the "OUT" to the valve bases. The Heater Supply will deliver 6.3Vdc, please note there is a trimmer potentiometer for any fine adjustment that might be required. Test this voltage under load conditions. No soldering required as they are screw terminals. If one side of the 6.3Vac is earthed which can be the case. Disconnect it and earth the negative side of the "OUT" of the PCB. Using the Tube Heater Supply will provide a much lower noise floor as the heaters will now be fed with a nice clean DC supply. 

PLEASE NOTE: The input AC voltage should not be more than 1V above the desired DC voltage output. So if you need a 6.3Vdc supply output for your valve heaters you have to have an AC voltage input of 6.3Vac to 7.3Vac.

The heater supply uses Schottky barier diodes for rectification. They provide clean switching and inhibit low voltage drop. 2 filter capacitors (6.800uF each) smooth the voltage. A discrete design, low drop voltage regulator feeds a power transistor at the output. A tenturn timmer allows for accurate adjustment of the output voltage. 

More tubes can be connected in parallel, assumed their respective heaters are at equal potential. If heater potentials are different, separate modules (and transformer windings for each module) are required. The heater reference needs to be connected close to the tube The total output current is limited to 1.5Adc, mainly due to heat dissipation. The units are factory adjusted at your order. After installation, the supply needs no adjustment. 

Specifications

Electrical 
• Output adjustable between 2.5V and 13V, specify when ordering 
• Output current maximum 1.5A 
Input voltage should not exceed 1 V above specification
• Minimum input voltage 4 Vac 
• Output noise < tbd uVrms (10Hz - 20kHz) 
• Output hum < tbd uVpeak at 100Hz / 120Hz 
• Output impedance < tbd mOhm 
• Fast switch-off function available on request (required if used to supply 9V section of philips CDpro CD drive) 
• The heatsink is not electrically isolated from the circuit and should be isolated from the chassis 
• The output is not short circuit proof 

Mechanical 
• Total size 40*60*40mm (W*L*H, heatsink included, standoffs excluded). 
• Weight each 60 gram (excluding packaging) 
• Hole pitch 31* 51mm, hole diameter 3.5mm 
• Needs 8mm stand-offs to mount on chassis, supplied with modules. 

Sold individually

Price (each)
£28.75 +vat +p&p