RF from input to output:

Up to 4 transceivers can be connected to the TRX selector module. The transceiver where the PTT was
pressed last gets the connection. (The module is of course optional, you can just as well use a manual switch). 

The RF then goes to the input Pwr/SWR coupler. The purpose of this coupler is to monitor the input
power. It is guaranteed that sometimes the transceiver is set to 100W and transmits into the PA,
resulting in smoke signals. If you have this input Pwr/SWR coupler, the controller can switch off the PA
in case of an error and switch the transceiver directly to the antenna.

From the coupler it goes directly to the PA. 

Since the control power from the trasceiver is practically always much too high, you need an input
attenuator. There are two alternatives: The PA has the connections FromATT and ToATT, here you can
loop in a 10dB attenuator from normal 3W resistors. But if you use the TRX selector module, this
attenuator is already provided there. In this case you can connect FromATT and ToATT directly.) 

After the PA follows another coupler, the Filter-Pwr/SWR coupler. The purpose of this coupler is to
detect a incorrect switched or defective filter. If possible, the filter will be switched automatically.
Nevertheless it happens sometimes that the wrong filter is selected and then this coupler helps to
avoid damages, because the controller switches off immediately.

Moving on to the filter bank. There are 6 switching outputs available which are sufficient to switch 7
filters. The controller has different band combinations and thus supports different filter configurations. 

Behind the filter is the third coupler, the antenna pwr/SWR coupler. Here, as usual, power and
SWR are measured at the antenna. 

Finally, at the output is the antenna switch. If you have more than one antenna, the controller can
automatically switch to the appropriate antenna depending on the band. This switch also provides an
ouput to an SDR, which is automatically connected to the antenna that is currenlty not in use.

Temperature measurement:

The controller DSP-7-PA has two inputs for temperature sensors (NTC type: B57703M103G)
One sensor is placed on the heatsink in close proximity to the power transistors. The second sensor can be placed close any other device that might need temperature monitoring (in my case the LPF).

The highest temperature of these sensor is used to control the Fan, power derating and overtemperature shutdwon. Once the temperature gets close to the overtemperature, the ALC voltage is lowered to reduce the ouput power instead of a complete shutdown, so you might be able to finish your QSO.