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Universal adjustable BIAS for RF amplifiers

To use a triode or more, with grounded grid a BIAS voltage is needed. This is achieved by means of expensive and hard to find high power zener diodes. Tubes such as 3CX1500/8877 or GI7B/GS31/35B, GI46B can require up to 30V bias and need expensive power zener diodes, (50W) which are fragile. This module is designed for voltages ranging from 3.5V to 50V. This voltage range is more than sufficient for Russian triodes, even with extreme anode voltages.

This is a "transistorized zener diode" equipped with a temperature compensated adjustable zener and a High Power transistor.

The printed circuit board is of professional quality, made of double-sided epoxy glass, with plated-through holes and tin-plated power tracks. 

Supplied; assembled, tested and ready to use, only the power transistor is not soldered (3 solders required), so you can adapt its position to suit the amp you're using. Anti-glitch, meters, Fuse protection and automatic "cut-off" (standby) resistor are also included in this module.

No other parts are needed, just install and connect the wires and power transistor. Detailed diagrams with parts list, PCB layout, setup procedure and installation diagram are available for download in PDF format.

Remember this circuit it is especially designed for a wide variety of high-power amplifiers, including home-made ones.

Note: Mounting hardware and transistor insulation, are provided.

***Important Remark***

The modules currently for sale on eBay equipped with TIP147 power transistors ARE NOT COMPATIBLE with high-power triodes such as GS31B, GS35B & GI46B; result…..! They smoke!

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Size: 5.1 cm length x 4.3 cm width x 2.5 cm high.

Good to know: An example of use on an amp made with 2 x GS35B and another with 2 x GI7B are provided with all the construction details you can rely on, if you want to make one.

***Please check the available space in your amp***

Compatible with the following Linear Amplifiers tubes

Tube(s)                     Grid current    Anode current        Bias voltage

GI7b                          100 mA                    0.35 A              12-15 VDC

2x GI7b                    150-200mA              0.7 A                12-15 VDC

3-500Z                     150-200 mA             0.75 A              9 VDC

2x 3-500Z                 350-400 mA             1.5 A                9 VDC

3CX800                     50 mA                       1 A                    5.1-8 VDC

2x 3CX800                100 mA                    1.5 A                5.1-8 VDC

3CX1500/8877        200 mA                    1.5 A                8-12 VDC

2x 8877                    400 mA                    3 A                    8-12 VDC

GS31/35B                400 mA                    1.5 A                24-35 VDC

2x GS31/35B           800 mA                    3 A                    24-35 VDC

And many others...

I ship worldwide

E-MAIL If you have any question, don't hesitate to ask me.

THANKS for your interest on this item!

Note: since part of the price has been transferred to the shipping price in order to minimize the taxes that buyers have to pay, I am unable to offer discounts on grouped shipments.

I Shipping via Priority International Flat Rate Envelope, in order to provide a delivery time, not too long.

I sent no later than 5 working days after payment.

***France is not the next door***

Transit time can be up to 4 weeks, (!! Be patient!!).

I do the maximum in terms of product quality, shipping, and packaging, for everyone to be happy.

***I aspire to have 100% positive feedback***

So I would advise to "impatient people" do not buy if you do not agree with these simple principles,

!!! Remember purchase is not compulsory!!!

Thank you *** to take into account these observations ****

And most importantly, thank you very much for almost 4000 buyers were satisfied.