Transverter Configuration

No contest really requires the logging of the actual frequency at which a contest contact was made, but it is very important to ensure that the contact was logged on the correct band, otherwise points may be lost, or even the contact may be disallowed. However it is very easy to forget to change the band on the VKCL screen after switching to another band on the transceiver, and even if it is realised that logging is on the wrong band, it is difficult sometimes to remember at which contact the band change was made to correct the log.

At HF and higher frequencies where the transceiver has direct output at the required frequency, the use of OmniRig solves the problem, as it allows synchronisation of the band and mode settings in VKCL with those on the transceiver. Logging is then always performed on the correct band and mode, with small exception with digital modes, where the transceiver does not always report the correct mode and additional action is required to log the contact as digital.

That happy situation breaks down when transverters are used to reach frequencies that cannot be generated directly by the transceiver. It is no longer possible to determine the band on which the contacts are made just from reading the frequency to which the transceiver is set, as it is only an intermediate frequency that may be added to or subtracted from another frequency close to the required operating frequency to obtain the final contact frequency. Other input is required to VKCL to determine the band in use.

External inputs to modern notebooks and even desktop computers are becoming rather difficult to implement as the 'standard' i/o ports of the past such as printer and serial ports just about disappeared from all computers. Ethernet and Bluetooth are possibilities, but the Universal Serial Bus (USB) is now ubiquitous and a suitable board is readily available in Australia for a moderate price.


The board referred to is the Top16 USB IO Module (pictured above), made by TCTEC, and is available from at least one suppliers. The board does require a specific driver for the FDTI USB chip on the board, but with WinXP Service Pack 3 and later, the operating systems appears to have the drivers already and automatically installs them when the board is first connected to a USB port.

With earlier systems, it may be necessary to manually install the drivers , but all the information needed to install the board is available from the manufacturers web site (The link for the FDTI chip drivers is on the TCTEC web site but may be rather difficult to find initially. The drivers are available from FTDI Ltd web site. The easiest way to install the drivers is to download the setup executable under Comments in the Windows row and to run it.)

In addition to the drivers, a file called top16.dll is also required, and it should be placed preferably in the root folder where VKCL is installed, but it can be located anywhere in the Windows search path. (This dll file will not be distributed with VKCL to avoid installing it for users who have no interest in this facility.)

The Top16 IO module has 8 open-collector outputs (above top right) that may be used to operate relays or other similar devices, and 8 analog/digital inputs (above top left), used as digital inputs only in this application. The board provides +5 volts, so that only a pull-up resistor and switch/relay contact is required to control an input. The outputs and inputs are numbered from 1 to 8, corresponding to least significant and most significant bits in the data byte respectively. The bits are read as '1' when the input is high (+5V) and '0' when the input is grounded.

The transverter configuration window is as follows, allowing configuration of up to eight transverters:


The Trvtr column is just for reference.

In the Inp Code column, the entered value represents the binary value of the 8 digital inputs bits seen by the Top16 board when that transveretert is activated. For simplicity, single input bits only may be used, so the code would be just the binary value of the input bit to which the control line is connected, for example, 1 for input bit 1, 2 for input bit 2, 4 for input bit 3, 8 for input bit 4, etc.

The Out Code is optional, but when specified, it represents the output bit or combination of output bits that will be activated when an input code for that transverter is recognised, and maintained activated while the input code is present. (Relays may be connected to those outputs to perform some useful function.)

The FM Only checkbox modifies activation of output bit(s), so that they are only activated when the input code is present and the controlling transceiver is in FM mode. The purpose of this function is to perform polarisation switching of aerials, horizontal for SSB and other modes, switching to vertical for FM mode.

The Radio selection buttons specify which transceiver to use to read the IF frequency.

The Offset (MHz) is essentially the oscillator with which the IF output from the transceiver is combined to generate the final operating frequency. If positive (default) the value and the frequency reported by OmniRig are added, if negative, the reported frequency is subtracted from the entered value. In both case, the resulting frequency is displayed as the radio frequency on the logging window and saved with the contact.

The Band/Notes column is there just as an indicator only of the band for which the transverter is configured. It is up to you to use the correct IF frequency and to work out the correct offset frequency for VKCL to use the correct band for logging. (These are plain text entry fields and other notes may also be added.)

The check box labeled Inverted to the right of the band column allows inversion of the logic connected to the input terminals of the board, to suit the control logic used to control the transverters. (Input bits that are not specified in any code can be left unconnected as they are filtered out when the input is read.)


In the above example, two transverters are configured, number 1 for the 23 cm band configured as an up-converter, so that, using a 2m IF frequency of 145.150 MHz, the offset is 1151 MHz to give 1296.150 MHz as the transverter output frequency that is displayed in VKCL and logged with the contact. Aerial polarity switching is enabled with the relay connected to the third least significant bit being energised when in FM mode. Transverter number 3 is configured for 9 cm as a down-converter so that the above 2 m IF frequency is subtracted from 3543.3 MHz to give an output frequency of 3398.150 MHz. (As shown, the slots need not be configured consecutively, and radio selection for unused slots does not matter. Also the IF frequency need not be the same for all transverters.)

The text below the configuration table shows the version of the top16.dll file installed and the "names" of the Top16 boards found connected to the computer. Many boards may be connected, but VKCL is programmed to only use the first board found. Diagnostic information is shown here if there are problems in configuring for transverter operation.


The buttons along the bottom of the transverter configuration window allow the configuration to be setup and just saved for future with Save Only button, to save and activate the configuration with Save & Activate button, and to stop using transverter control with De-Activate button. Depending on implementation, it may be necessary to activate and de-activate transverter control on a regular basis, and to avoid the need to bring up the configuration window each time, a check box becomes available under the radio selection buttons to suspend transverter control without de-activating.

Transverter control not activated.

Transverter control activated but suspended.

Transverter control activated and in use.

The above three images show transverter control de-activated on left, transverter control activated but suspended in the middle so normal radio selections can be made, and on the right the transverter control active and taking over the selection of the radio as configured. The selection of a transverter is "sticky". If input code is removed from the IO module, the last selected transverter remains active until next valid input code is received or transverter control is de-activated.


Ideally the input to the Top16 board should be derived from the switching needed to use a transverter on a particular band so that VKCL is automatically synchronised with the hardware in use. Failing that, a manual rotary switch or even toggle switches can be used for input, and although that is probably not much better than changing the band directly in VKCL, it does encourage automation and provides the means for it,


NOTE: The above facility may also be used to simply select the radio to use even when no transverters are involved. When using two radios with VKCL, it is just as easy to forget to select the current radio in use, as it is to forget to change to the current band in use. Configuring two "transverters" each one using a different radio, and setting the Offset (MHz) to zero, will result in the appropriate radio to be selected and no change made to the frequency read by OmniRig from that radio.

The only "trick" is to derive an input to the IO board which indicates which radio is currently in use. Some possibilities are to intercept the push-to-talk input to the radio, or the keying line from the radio to an amplifier, although in both cases the indication only appears when transmitter is activated and not ideally when attention is transferred from one radio to the other. A pressure plate in front of tuning knob where the wrist might rest, or a capacitive detector? Suggestions welcome.


Other Transverter Solution

Several operators with software and hardware knowledge and expertise have designed and built their own transverter controllers to integrate the transverters with their station. These controllers read the transceiver frequency and work out the final output frequency of their selected transverter. The controllers, not the transceivers, are connected to the logging computer and respond to VKCL OmniRig frequency read requests.

However, only 32-bit integers are used by the OmniRig interface so that microwave frequencies cannot be transferred directly. The controllers therefore divide the transverter output frequency by 1,000,000 so that the resulting value is in the LF range, below any band used for contesting. When VKCL gets frequency reading from OmniRig in the LF range, it first multiplies it by 1,000,000 before using it to determine the band to use. The frequency resolution is now only 1 MHz, but that is enough to correctly select the band for logging.


Single Transverter ( Proposed )

A popular transceiver used for field days is the Kenwood TS-2000X which covers directly up to 23 cm and has provision for a 'transverter mode' to integrate with a 13 cm transverter using 2 m IF frequency. When in transverter mode, the dial read-out is in the 13 cm band, but the output is up to 5 watts on 2 m band and the OmniRig reading is also in the 2 m band.

Using a transverter such as the Kuhne TR2320H-2400 with Opt: S for 2402-2404 MHz output with 144-146 MHz IF input, the IF frequency would be 145.150 MHz to give the popular 2403.150 MHz calling frequency on 13 cm. This is 1 MHz higher that the normal calling frequency of 144.150 MHz on 2 m, so again VKCL could recognise the difference and switch to 13 cm band if it reads a frequency in 145-146 MHz range in SSB mode (to allow use of those frequencies on 2 m in FM mode).

Use of this mode for transverter operation would also have to be enabled to ensure that it does not interfere with any other use of 2 m at other times, and the IF range to monitor could be made variable to cater for other possible hardware combinations. (Suggestions invited.)


Page last modifies:10/ 8/2016