Summary of issue: Other than dual band \ Satellite use, to have a two way RF communications, the receiver and transmitter have to be on the same antenna. The problem is with SDRConsole’s LimeRFE module it does not allow TX & RX on the same jack \ antenna, where SDRAngel does. There would need to be a relay output configured as PTT to use an external relay to switch the antenna between jacks.
Background: I am hearing impaired, so for VHF+ contests I prefer to use FT8. For that reason I would like to get the combination of WSJT-X, SDRConsole, LimeSDR and LimeRFE to work. I had enough time, patience and equipment to play with SDRConsole, SDRAngel along with LimeSDR and LimeRFE, to figure out what details I was missing.
Details: In SDRConsole’s LimeRFE Module when you try to use a common port for RX and TX it creates an error message saying it’s not allowed. To use a different port for receiving would require one of the relay outputs on the LimeRFE as a PTT output to control an external relay. As there are no relay outputs for PTT, I have no way to switch the antenna between jacks to be successful on FT8.
SDRAngel can use the same jack for RX & TX. It’s LimeRFE module has a button to toggle the LimeRFE between RX & TX so that RX & TX are on the same antenna. To confirm the use of a single jack, I used SDRAngel’s LimeRFE control module and SDRConsole (without it’s LimeRFE module) and it allowed SDRConsole to use a single jack \ antenna just like SDRAngel could (this will be my temporary solution).
The information provided by Myriad for the LimeRFE info is not the clearest. Looking at their block diagram helps understand their intent. They intended J3 to be RX & TX for 100 MHz through 4000 Mhz. Along with J5 being RX & TX for 1 MHz to 70 MHz. They say there are limit’s on doing so, but the limits are not clearly defined what the limits are (cross talk?).
Next the menu in SDRConsole for the LimeRFE is confusing to me. The device has two ports that can be used for TX/RX so it's not clear which port it's impacting when you select TX/RX. In the port selection you need to be able to see which RF jack its going to use, such as in J3, J4 or J5. Port J4 is transmit only and limited to 100 MHz to 4000 MHz. SDRAngel menu handles the config of the LimeRFE in a way that is clearer to me. See:
https://github.com/f4exb/sdrangel/blob/ ... /readme.md
Minor Items:
In the SDRConsole the information in the configure for the LimeSDR is incorrect. For the original LimeSDR the LNAL is 1.5 GHz and below, not 2.5 GHz and below. The LNAH has the same issue, as it's 1.5 GHz and higher. Other versions of the LimeSDR have different frequencies for their break point (a pain for the software developer). Additionally the wideband jacks low frequency is dependent on whether or not it has the Ham HF tweak.
I do like the fact that the SDRConsole’s LimeRFE module automatically changes the settings of the LimeRFE module when you change bands.
It’s not clear on whether or not you have to leave the LimeRFE module Window active or if you can close it. I assume it has to stay open, so I am leaving it open.
One other minor comment is when using SDRConsole (through the LimeRFE) on 222.1 MHz, there are two spurs about 210 KHz above and below the carrier and they are 51 dB below the carrier (FCC Limit is 50 dB, so it’s OK). With SDRAngel the spurs are about 420 KHz away from the carrier and are 60 dB below the carrier (which is better). Measured with a HP 8561A along with a 20 dB 20 Watt attenuator. I am getting the specified power out of the LimeRFE on J3.
Jim, WB8VSU