Juma TRX-2 Firmware v1.20a

Software developed by Adrian

Juma TRX-2 Firmware v1.20a

Postby 5B4AIY » 12 Jan 2015 09:40

Firmware Version 1.20a Build 10 for the Juma TRX-2 introduces a new feature, (dBm Power Display) and greatly modifies an existing feature, (Auto-Equalise) as well as improving an existing feature (Very Fast Tuning Rate exit).

New Feature
The latest version of the firmware for the companion PA-100D linear amplifier included the facility to display the output power either in Watts or dBm. It seemed a sensible idea therefore to include this facility into the TRX-2. There is now an additional User Configuration menu item that allows this selection to be made. As this uses an additional word of the EEPROM, this will cause a checksum error on initial boot up with this firmware. Please make a note of your existing calibration and configuration settings before loading this new version so that they can be restored.

Note that the dBm display is logarithmic. The maximum output of the transceiver is 10W, +40dBm - do not exceed this! Remember, +37dBm is 5W, +43dBm would be 20W! Equally, the power meter display is inhibited for very low output powers. As the calculation involves using the log10() C function, a zero value for output power would result in a Math Error trap, so the display is suppressed for powers below about +6dBm.

I strongly suggest observing the graphic power meter display when using the dBm option. The graphic scale is preset so that full-scale is 10W, giving a positive indication that you are not exceeding the maximum output power rating of the transceiver. The dBm scale is very useful when testing cables, couplers, etc, as it allows you to easily assess their coupling loss in dB, particularly when used in conjunction with the PA-100D.

The gain/frequency characteristic of the driver and PA stages and their associated low-pass filters is not completely flat across the amateur bands. The original firmware incorporated a manual method whereby one could equalise the power output across the amateur bands, but it was a tedious, calculation intensive process. Some firmware revisions ago I automated the procedure, and this feature became part of the Serial Test Suite. Unfortunately, it did require the use of the serial port, and a laptop computer connected to a USB to RS-232 converter, and running a terminal program. As a result, it did not tend to get used very often either for its intended purpose of equalising the output power or as a diagnostic tool to isolate filter/amplifier problems.

This new version of Auto-Equalise is capable of being invoked as before, remotely from a serial terminal connection, but also now locally from the transceiver's front panel, dispensing with the need to use the serial port.

To use the Auto-Equalise function from the front panel, connect the transceiver to a good 50-ohm dummy load capable of dissipating at least 5W. From the power-OFF state, press and hold the FAST/VFAST button, and power up the transceiver. Continue to hold the FAST/VFAST button until you see the message:

Automatic RF
O/P Equalisation

At this point, release the FAST/VFAST button and you will receive the prompt:


Briefly press the MODE button to proceed, or the PWR button to abort. Assuming you wished to continue, after pressing the MODE button you will receive a prompt:

Press and hold
PTT to start...

Press and hold the PTT switch. The top line of the display will show the graphic power meter and the digital power display, in either Watts or dBm, the lower line of the display will show the current test frequency, starting at 28.850MHz and continuing down to 1.9MHz. If either an error occurs, (SWR, Overcurrent, High/Low Voltage, Low output power) or the PTT switch is released, then the function will gracefully abort without making any changes. Otherwise, a calculation will be performed to determine the optimum settings for the attenuator for each of the amateur bands, and the result will be displayed, similar to this:

17m 010010110
PWR to exit...

The first figure is the reference band used for the calculation. This is the band having the lowest measured output power. The second 9-digit string represents the attenuation settings for the 9 amateur bands in the order, from left to right, 10m, 12m, 15m, 17m, 20m, 30m, 40m, 80m, and 160m. In this case, the 17m band was the reference, and its digit will be blinking to further remind you. As you can see, in this actual example, the 10m band requires 0dB, the 12m band 1dB, the 15m band 0dB, the 17m band 0dB, and blinking, the 20m band 1dB, the 30m band 0dB, the 40m band 1dB, the 80m band 1dB, and the 160m band 0dB.

By briefly pressing the PWR button, the display will clear, and the transceiver will drop into its normal operating mode.

The Auto-Equalise function can also be invoked from the Serial Test Suite, in which case considerably more diagnostic information is available. To use this mode, again ensure that the transceiver is connected to a dummy load. In the User Configuration menu set the Serial Port mode to TEST. Unless you have a reason to use a different speed, leave the port speed at its default setting of 9600 Baud. Connect the RS-232 port of the transceiver to a suitable serial port on either a laptop or a desktop computer, usually via a USB to RS-232 converter, and launch a terminal program. Set the terminal program to 9600 Baud, 8 bits, no parity, 1 stop bit, and no flow control. Ensure you can reliably communicate with the transceiver.

Enter the letter Q (upper-case Q) and respond to the prompts. Press and hold the PTT switch to start the equalisation, and when the process is complete, release the PTT switch. You will receive a data dump similar to this:

Auto Equalise RF Output Power
Ensure transceiver is connected to a 50 Ohm dummy load.
This may alter your current attenuator settings.
Do you wish to continue (Y/N)?: Y
Press and hold the PTT switch to start...
Band: 10m Average Power: 4.6W : +36.6dBm
Band: 12m Average Power: 5.3W : +37.3dBm
Band: 15m Average Power: 5.0W : +37.0dBm
Band: 17m Average Power: 4.5W : +36.5dBm
Band: 20m Average Power: 5.8W : +37.6dBm
Band: 30m Average Power: 4.8W : +36.8dBm
Band: 40m Average Power: 6.2W : +37.9dBm
Band: 80m Average Power: 5.7W : +37.6dBm
Band: 160m Average Power: 5.0W : +37.0dBm

Band: 10m Rel Power: +0.09dB Attenuator: 0dB
Band: 12m Rel Power: +0.76dB Attenuator: -1dB
Band: 15m Rel Power: +0.44dB Attenuator: 0dB
Band: 17m Rel Power: +0.00dB Attenuator: 0dB <- Reference Band
Band: 20m Rel Power: +1.12dB Attenuator: -1dB
Band: 30m Rel Power: +0.28dB Attenuator: 0dB
Band: 40m Rel Power: +1.37dB Attenuator: -1dB
Band: 80m Rel Power: +1.04dB Attenuator: -1dB
Band: 160m Rel Power: +0.48dB Attenuator: 0dB
Release the PTT switch to complete...

Equalisation Complete!

Note that this method gives complete information regarding the output powers obtained, as well as identifying the reference band. You can also obtain a dump of the current attenuator settings for all the bands using the R command thus:

RF Attenuator Settings
Filter Attenuator
28MHz 0dB
26MHz 1dB
23MHz 0dB
19MHz 0dB
15MHz 1dB
12MHz 0dB
8MHz 1dB
4MHz 1dB
2MHz 0dB
1MHz 3dB
600kHz 3dB
300kHz 3dB

As well as equalising the RF output, the facility is also a useful diagnostic tool. If the transceiver has been carefully built, and its filters properly assembled, then the equalisation settings should be similar to those above. If you see 2dB attenuations, or, worse, 3dB, then this indicates a serious problem with one or more of the filters and needs investigating. The filter of the reference band should be thoroughly investigated for bad soldered joints, open circuits, relay selection logic faults, or other defects.

The System Calibration & Setup mode now also has an additional page which allows you to individually adjust the attenuator settings for each amateur band. The display is the same as for the local invocation of the Auto-Equalise function. To select an amateur band, briefly press the FILTER button. If the button is pressed and held, the band will automatically cycle through from 10m to 160m, and back to 10m. Release the button when you have selected the desired band, and adjust the attenuator value with the VFO knob in the usual way. The selected amateur band is displayed numerically, and its relevant digit will also blink.

Finally, it is still possible to adjust the attenuator of the currently selected amateur band. Select the TUNE mode, and, ensure that the transceiver is connected to a dummy load or well matched antenna, and press and hold the PTT switch. To enter the attenuator adjustment mode, press the PWR button whilst holding the PTT switch closed. If the second function has been set to the LATCHED mode, you will hear a series of beeps indicating the function has been latched. In which case, release the PWR button, and now adjust the attenuation value with the VFO knob. The top line of the display will show both the graphic and digital power meters, the bottom line will show the current attenuation value. If the second function has been set to the PRESS & HOLD mode, continue to hold the PWR button and adjust the attenuation with the VFO knob. To exit, release the PTT switch, and the PWR button, if held. The new attenuation value for this band will be saved to the EEPROM.

This version of the Auto-Equalise function has been completely re-designed, and now gives much more repeatable and reproducible results. The power used is now much lower than before, which ensures that the driver and PA stages are operating away from their gain compression points and on the reasonably linear portion of their transfer characteristics. The design of the PA is such that at high temperatures the bias is reduced thus tending to protect the amplifier from excessive dissipation, but this characteristic also changes the power gain. Thus, in the previous versions, repeated invocations of the function in rapid succession tended to give variable results. It also had the effect of increasing the thermal stress. With reduced power, as well as turning the RF off between band switch operations, the thermal stress is much lower, and the results readily repeatable.

Tuning Rate Feature Change
The second function (Long Press) of the FAST/VFAST button is that of engaging the Very Fast (1kHz) tuning rate. In the previous build and all previous versions of the firmware, the only way of exiting from the Very Fast tuning rate was by briefly pressing the FAST/VFAST button, whereupon you would be returned to the default Medium tuning rate (10Hz). After using this for quite some time I found that, especially when using a digital mode, I would then have to re-select the Slow tuning rate (1Hz). This build addresses this, and now there are two exit possibilities. The first is as before, a brief press of the FAST/VFAST button which returns you to the Medium (10Hz) rate. However, there is now a second exit. By pressing and holding the FAST/VFAST button you will now exit to the Slow (1Hz) tuning rate.

CW/CWR Modification
The 'sense' of the CW/CWR mode has been reversed to agree with that of my Elecraft KX3. In this version, the CW (Normal) mode now uses LSB, and the CWR (Reverse) mode uses USB. From a practical operational standpoint it makes no real difference except that when tuning in a CW signal the pitch change with VFO knob rotation is now the same as with the KX3. In the CW (Normal) mode, a clockwise rotation of the VFO knob increases the pitch. Interestingly, my Yaesu FT-450D works in exactly the opposite way, as does my Kenwood TS-2000, whereas my Icom IC-756 Pro-III works the same way as the Elecraft KX3, so there does not seem to be an agreed standard. However, it does seem to be more logical to have an increase in pitch with a clockwise rotation of the VFO knob.

A minor bug has been fixed. When restoring the defaults, the mode of VFO-E and VFO-F was incorrectly set. This is now fixed.

NOTE: As the EEPROM mapping has changed, this version of the firmware WILL CAUSE A CHECKSUM ERROR on first execution! This is normal, and only occurs the first time. Make sure to make a note of your calibration and configuration settings prior to loading this firmware! After the initial checksum error, the standard defaults will be loaded. Switch off and then enter the System Calibration & Setup mode and re-enter your calibration settings. Exit and save these, and then enter the User Configuration mode, and re-enter your configuration settings.

If you are upgrading from an original version of the firmware, you will have to re-calibrate your transceiver as the measurement system is completely different, and there is no 'easy' way to 'translate' the old calibration settings into the new version.

73, Adrian, 5B4AIY
Juma TRX-2 v1.20a Build 10 (C-Source+HEX Load File+User Manual).zip
Added power display in dBm, major modification to Auto-Equalise, V-Fast tuning rate exit, minor bug fix.
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Re: Juma TRX-2 Firmware v1.20a

Postby sm0jzt » 23 Mar 2015 07:14


You are fantastic. I will give it a go on my TRX-2

SM0JZT / Tilman
http://radio.thulesius.se Swedish pages for radio experiments and QRP homebrewing.
Posts: 4
Joined: 12 Nov 2011 10:58
Location: Sweden

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