Poweramplifier with QQE06/40
Frequency : 70MHz
Output power: 50 tot 100 watt
Valve: QQE06/40
Input power : 1-2 watt or 5-10watt
Pre-amp gain : 20dB
The purpose of this amplifier is to use it with a converted CB transceiver somewhere else on this site.
The chassis comes from a T-28/APT-1 VHF (90-220MHz)Jamming unit that dates back to WWII.
The poweramplifier makes 90 watt at 1.5 watt input power.
The amp can also used with an input power of 7 watt by using an input attenuator.
It has proved to be stabile under all circumstances.
The amplifier is finished and here are some pictures taken during building :
Top and bottom view:
The schematic is drawn by the use of
kolourpaint :
Some blocks in the schematic:
- Pre-amp : 20dB preamplifier
- filter: mainsfilter from an old microwave oven
- low pass filter: ready bought filter for 70MHz 100 watt with RF detector
- ATT : 8 dB 10 watt attenuator
The preamp is build with a BFR92 transistor in a SOT23 housing.
On the input of the pre-amp there is a bandfilter which is simulated with PUFF.
The output of the pre-amp is a simple 100 ohm resistor output.
The benefit of this output is that the gain is relatively low and the amp remains stabil.
The pre-amp does about 20dB and can be very usefull.
Schematic diagram of the preamp:
