16. 8. 2021

JUMA PA1000 CAT driven from ICOM IC-705 e.g. OTRSP to YAESU BCD controller

Another gadget from my workshop again primarily for the needs of CDXP is the JUMA PA1000 control with the ICOM IC-705 transceiver.

IC-705 is a very nice radio that can easily drive the JUMA PA1000 to 1000W output power. At the same time, the weight of both devices is so low that it fits within the limit of 8 kg of hand luggage onboard the aircraft.  Therefore, this combination appears to be the optimal expedition equipment for both one-man expeditions or multi-ops expeditions, where checked luggage is used for other equipment and antennas. The IC-705 has the additional advantage that complete communication and control, including audio / input-output, goes through one micro USB cable. So there is no need to bring other interfaces for CW, SSB, RTTY, FT8, etc. However, this advantage becomes a disadvantage if you want to connect another device to the IC-705, which should perform some activity based on the selected band/mode and similarly. The IC-705 does not have a typical ICOM CI-V output to which more devices can be connected and thus control an antenna switch, power amplifier, bandpass filters etc. Therefore, the following converter was created to control the JUMA PA1000, ie switching bands in PA according to the selected band to TRX.

Video with IC705+JUMA PA1000

(video is on a safe server, due to the size I can not upload it here)

The basis of everything is a logging program that can communicate with the IC-705 through virtual serial ports, which arise after installing the appropriate ICOM drivers. At the same time, it can communicate with an external device using the OTRSP protocol. A description of the protocol can be found HERE. In short, this protocol is used, for example, in automatic antenna switches, etc.

The JUMA PA1000 does not know the OTRSP protocol directly, so a converter must be inserted between the logging program and the PA that will arrange the conversion between the OTRSP protocol and another format acceptable to the JUMA PA. I chose the YAESU BCD code.

In practice, it looks like the logging program periodically reads the frequency from the IC705. In the event of a band change, the logging program sends the appropriate code to the converter via the OTRSP protocol, which switches the PA via its outputs.

The whole converter contains a USB / serial converter and a powerful microprocessor with its own firmware. So there is no need to have a computer with a serial port, just have a free USB port. The entire converter is also powered from the USB port, so no external power supply is required.

The mentioned converter was tested with logging SW N1MM +, Win-test and DXLog. It works without any problems with proper configuration.

Example of N1MM+  configuration for this converter

However, the converter can also be used for other devices. It can be used to control, for example, antenna switches that have YAESU BCD inputs. It can be used in the same way if you use a TRX Kenwood controlled via serial port or USB and you do not have any other embedded interface, for example from Microham. It can even be used to control 4-port antenna switches. Here it is necessary to amplify the outputs for example by using transistors and properly configured OTRSP table antennas in the logging program.

It is always necessary to keep in mind that the correct logging program must be used and the communication between this program and the TRX must work. Otherwise, the converter will not work!

If you are interested in a finished converter, contact me by email. The converters will be available in October 2021 at the earliest.

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