Projects : Triode Bias Board

To use a Triode a Bias or zero signal current is needed. In "ancient" times it was done by a zener diode. But with popular tubes like 3CX1500 / 8877 / GS31b / GS35b we should need 50W zener diodes. These are hard to find, easy to break and expensive. This board is a "transitorized zenerdiode" It contains a TL-431 "adjustable zenerdiode" and a buffer darlington transistor. For higer voltage than the normal max 39V an aditional 15V zener diode is added to get as high as 54 Volt. In 2019 the board was redesigned and a second potmeter +Jumper/switch was added. This was done to be able to switch bias settings for different modes. Now there is an ability to switch between Class "C" and Class "AB1"

Several people already designed Triode bias circuits this circuit is in use and has been copied by many hams all over the world. It is basically the reference design from the datasheet.

Kits are available for 16 Euro each or a special offer 3 kits for 42 Euro. A Kit contains a bare circuit board, and all components. There is NO mounting hardware or heatsink supplied

Shipping will be 7 Euro for Europe and 11 Euro for the rest of the world. Shipment costs remains the same (You only pay shipment for 1 kit) regardless the number of kits you order. Payment via paypal or banktransfer

For more info send me an E-mail to John at mycallsign dot nl