Discussion in 'Amateur Radio Amplifiers' started by K8TDN, May 30, 2019.
thanks for the information..Ted
Other ways to do this are series connected low cost fixed attenuators with 5 watt ratings or series total power ratings at low cost. The input attenuator needs to be the highest power rating then up the line the power callability goes down according the previous attenuator out put level if a series string is used..
Another way but more expensive is the variable attenuator with BNC or SMA connectors and cables.
Going this route with either form will require a switch around circuit to short across the attenuator so receive sensitivity in not affected.
If you do a resistor network, it would be the same unless you can install it in the transmitter so receive is not attenuated.
I have done these ways in a home brewed 222 band transmitter where the amplifier has very high gain and needed the driver power reduced.
I have a variable in 1 db steps and a fixed attenuator in series for total output and input power control within the limits of both the amplifier and the driver stage.
Results are the driver can be used through to the antenna or the drive power to the amplifier adjusted up to 190 watts on FM and lowered for SSB and linearity.
Yes it's more expensive but the pleasure of full control afterwards is worth the effort and extra cost.
By the way, commercial attenuators are built differently inside, especially the higher power ones with heat sinks. That's how they get the wide band performance and still keep 50 ohms resistance at very high frequencies.
Ebay is great for attenuators. Just be sure that they are 50 ohm & not 75 ohm.