2.4Ghz Transverter

  

 

2.4Ghz Transverter       VK3XDK

 

The Transverter series was deigned for good performance and ease of build/Faultfinding. The Modules are keep small and have facilities for bias tees allowing remote mounting. All units have intensionally been kept to a minimum with an "add sections to suit" philosophy. (ie RFpreamp/filter, IFamp/filter).

 

          RX

 

The 2.4Ghz rx section features a NE32584 HJfet on the input, biased at 10mA and about 2V drain-source. The fet uses inductance on the input and microstrip matching on the output for a gain of around 14-16db and Noise figure of less than 1db.

The second stage uses a sirenza MMIC sga4586 with 3.6V (45mA) fed to its output. These MMICS feature good gain at 2.4Ghz (around 16db) and a low Noise figure of around 2.3db.

Following the second amplification stage is a Murata Bandpass filter module (DFC32R44PO84BHD) with a bandpass of around 120Mhz (loses of less than 3db) and a ESMD-169 Double balanced mixer. This particular mixer likes an LO drive of over 7dbm for low  conversion loses (10dbm Mixer). Other mixers (ie Minicircuits SYM-11) will fit the board and work well.

The  filters and mixers were purchased through ebay but equivalents should be easily available through other sources (they seem to be a fairly common pcb footprints).

 

                With an LO input of >7dbm at 1971Mhz,   Overall (conversion) gain on the receive section has been found to be over 20db!

 

 

          TX

 

The 2.4Ghz tx section also uses the ESMD-169/Murata filter combination.
Following the filter is an ERA5 MMIC with 4.9V (65mA) on its output.This device has good gain (around 17db), a high P1(around 16dbm at 2.4Ghz) and are easily obtainable.

The final output stage Uses an SXA389B with 5V (115mA) on its output.  This device features an output of 250mW (25dbm)!! and 12.5db of gain at 2.4Ghz. (suitable attenuators are a must when testing!!!)

 

 

                With an LO drive of >9dbm and IF drive of 0dbm at 432Mhz, output has been found to be over 16dbm

                With an LO drive of >9dbm and IF drive of 10dbm at 432Mhz, output has been found to be 24dbm

                (All spurs down by > 40db)

 

 

 

           Capacitors

 

All coupling capacitors and '1/4 wave' grounding capacitors are 16pf ATC100 (2.4Ghz series resonant)

Other capacitors (not so critical) are standard smd (805) types and 10uf/16V tantalums.

 

 

            Resistors

0805 and leaded

 

 

            Other components

 

            NE32584                   (NEC)                        Hj FET  biased at 2V 10mA.

            SGA4586                  (RFMD)                      MMIC (low noise)

            SXA389B                  (RFMD)                      MMIC (1/4Watt output (25dbm))

            ERA5                       (MINICIRCUITS)           MMIC (High gain, High output)

            ESMD-169                (MA-COM)                  10dbm double balanced mixer (x2)

            DFC32R44P084BHD  (MURATA)                  Bandpass filter module (X2)

            ICL7660                                                     Negitive voltage generator (hjfet bias)

            SMA Connector                                          Edgemount (X4)

            MCX Connector                                          Topmount (X2)

 

 

            PCB