QRP attenuator  50W / 5 W
I operate both QRO and QRP power levels. My QRO power is 1kW and on QRP I run 5W.
As I have separate call signs for QRO and QRP, OH1TV and OH1WX, I often work DX-speditions
with both calls. Threrefore I need to adjust power levels quickly and often. But it is time consuming.
I have also tried separate rigs for both powers. It is not convenient either.
So I decided to build this QRP attenuator.  My linear needs 50W drive, that is, the exciter is adjusted to 50W.
By attenuating that 50W by 10 dB I get 5W, by turning one switch.
On QRO I can have the full kW in the other position of the switch
This attenuator acts like a negative Linear Amplifier.
The schematics is very simple as you can see. I built it from the parts I had in hand.
I had to connect two resistors in series to get the needed resistance values.
The 10 pF capacitor was necessary in order to improve impedance matching on the high end.
The measured attenuation was 10.2 dB +/-  0.2dB over 1.8…52 MHz band.
Return loss is better than 20 dB on 50 ohm..
The LED lights during QRP transmission.
OH1TV
19.10.2007
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