Directional Couplers with RF
output and DC output for 145MHz - 435MHz.
The use, copy and modification of all info on this site is only permitted for non-commercial
thereby explicitly mentioning my radio amateur call sign "PA0NHC" as the original writer / designer / photographer / publisher.
Tests (in 1999) on finished prototypes like above showed nearly NO reflected power at 25W transmitter output, when terminated with a good dummy load. It clearly showed differences in return loss between different types of low power 50/51 ohms terminating resistors, and higher power dummy loads. Good terminators showed up to 30 dB return loss.
Possible uses :
The RF-output directional couplers + a portophone or signal generator + a step attenuator + a common receiver with the S-meter as indicator, can be used to measure with very low RF power the return loss of :
- small receiver filters
- large cavity filers
- large helix filters
- low pass
- high pass
- band pass.
- antenna systems
They also can be used to safely inject RF signals into a live operating repeater, and measure
- its real practical sensitivity
- the correct action of the CTCSS system
- the squelch action
- large signal handling (blocking).
- the duplex filter using a portophone at low power and step attenuators
- frequency characteristic
- up to -120dBc suppression at the notch frequencies
See PI3RTD and pa0nhc cavity filter .
output couplers + the RF power from a
transmitter can be used to measure :
- RF transmitter output (1W - 800 W)
- returned power from loads such as antenna's (1W - 800 W)
- to high VSWR to shutdown a power amplifier or driver stage.