BATC Forum

The PLUTOSDR has 2 ports for coax cables (TX and RX). In my situation, in my laboratory I am only able to use one coax cable for both transmitting and receiving (i.e. it is going to be used for an antenna, and there is only one coax cable that goes to the roof). It is possible to do this, as this cable and set up can handle signals in both directions.

My question is: Which port do I connect the coax cable to in the Pluto SDR (TX or RX), if this cable will be both transmitting and receiving? This cable will then be connected to a PA, then to bias-t, then to the antenna in the roof. Should I use a diplexer placed between the SDR and the PA? I am concerned because the frequencies are too close together (uplink: 437.5 MHZ, downlink: 437.45 MHz).

Thanks in advance.

No, the Pluto cannot use just one port. You would need to add a relay to the two ports to combine them into one signal.

Colin G4EML

Or a passive splitter might work for you, subject to the levels you plan to send. Satsagen uses a pair of 10dB attenuators and is safe to 'tx into itself' but AFAIK its more to do with a better match than the actual RF level.
Maybe something like this? eBay item 265657102955 (some frequency dependency) or this 296293986096 which should be broader and gives about -6dB isolation/loss anyway.
Gareth

Why not put the Pluto on the roof and use a LAN connection? You must have power already on the roof for the PA etc. You could use WiFi for the LAN too. I use a LAN and power ( mains ) cable to my roof for 23cms from a Pluto. You can also use the mains cable for the LAN with range extenders if the mains cable is the same ring main.
You then could use the spare coax as a 'test' cable to send/receive a signal to near the Pluto to see if it is TX or RXing OK.
Martin G8LCE

You need to use the TX port on the PlutoSDR. TX works in both directions, so just connect your cable there. Using a diplexer between the SDR and PA is a good idea, but remember the frequency difference is small. It might be hard to separate. Don’t forget, a good filter can also help with signal separation. Just make sure the PA and bias-t are well-matched.