The CP1 is a very useful tool in the ham shack, especially that of a homebrew enthusiast. It is a dual directional coupler that provides high directivity, can be internally or externally terminated and can be constructed with a coupling loss of either 20 dB or 30 dB. It can be used to sample a transmitter's forward power and reflected power output.
As an example the forward power port can be connected to an oscilloscope for display of the transmit envelope. It is an ideal companion to the 2T-Gen 2 Tone test generator.
For more advanced applications is can be used with a spectrum analyzer and tracking generator to sweep the return loss (SWR) of an antenna or other device in real time over a frequency range.
Q: May I use the CP1 as an SWR and/or RF power bridge?
A: Yes. The CP1 separates the power flowing in each direction on a transmission line. By measuring the power at each connector, an accurate measurement of forward and reflected power can be made. This is very useful when matching an antenna, the input to an amplifier, or other devices. SWR bridges and power meters use a similar coupler, driving a diode detector.
Q: How do I use the CP1 with the 2 Tone Generator (2T-Gen)?
A: An ordinary oscilloscope may be connected to the forward power connector and used as a monitor scope. When used with a spectrum analyzer, the CP1 can be used at either port to observe the transmitted spectrum, including IMD if used with the Elecraft 2T-gen or other 2-tone generator. If a sweeper is substituted for the transmitter, then swept-frequency measurements can be made.