In February 2013 I start with my second linear with two GI7B. I was finish in May 2013.
I made experiments with microwave oven transformers. The problem is the overheating of this transformers. This transformers was build for impulse usage, and not for a permanent use. So I find a circuit in the internet from a other OM. He control this transformer with a LM393 IC. But you need a big transformer from a Moulinex Microwave oven.
I build a cooling case for the two tubes
The back side with the fan on the cooling case
The under side with the input circurit
The front side with the two tubes and Plexiglas
Inside the linear. The roller induct-or is under the metal slide with the PI-Filter.
The front of this linear
The power and header switch
The roller induct-or with counter
The external power supply
Inside the power supply. This is a microwave oven transformer. He is controlled by a integrated circuit.
The maximum output on 80m SSB.
You can make 800 Watts with this linear on 80m SSB. It works fine for a long time.
Here you can download the schematics for the power supply: netzteil-2GI7.sch
Here you can download the schematics for the RF part: HF Teil. 2GI7
This is the connection plan for the regulated microwave power supply
This is the control schematics for the regulated microwave power supply
It works with a microwave oven transformer, but the power supply make a noise like a beating heard, when he is regulated the voltage 🙂
I sold this linear, after a longer usage.
