The Qualcom Transverter


The finished Qualcom transverter

When the disposal Qualcom equipment became available, it opened an opportunity for amateurs to get onto 3 cm without too much trouble

The Qualcom satellite system was easily modified to 3cm and it was quickly bought up by a large number of Australian amateurs. The unit consisted of a PLL 2.6Ghz oscillator, the transverter module, a power supply and a 1 watt transmit amplifier.

The PLL oscillator only needed re-programming to the required frequency, an additional 10Mhz reference oscillator, and some minor modifications to the loop filter.

Shown in the photo is the PLL and its reference oscillator. The PLL chip has a heat sink bolted over its top surface and the PCB is mounted to a 5mm thick chassis providing further heat sinking for the PLL chip.


Reference oscillator and 2.6 GHz PLL

The transverter is modified by removing the strip line filters and replacing them with pipe cap filters. The base chassis has to be machined to accommodate the filters which are soldered to the PCB underside.
Modified Qualcom 10 GHz transverter board


1 watt HPA at bottom and transverter power supply at top.

Three filters are fitted, one to the receiver RF stage, one to the oscillator multiplier and one to the transmitter post mixer stage. The power supply develops all voltages for the transverter and power amplifier. It has an on board TR switching, and the only extra supplies needed are for the PLL oscillator and antenna relay, if used.

On my transceiver I used two 400mm dishes arranged, one for receiving while the other is used for transmitting. The dishes are accurately mounted onto a base rail mount, so that they both point coaxially along the same shot line. The 1 watt amplifier board is mounted on the same chassis as the power supply as seen in the photo. This module requires little modification to produce 750mw to 1 watt at 3cm.

The overall performance of the transverter is superior to the DB6NT design primarily because of the three receiver front end stages and the higher output power.