G3WDG050 50W 23cm PA
A new PA development for the 23cm band using a modern discrete device is available.
Available modern semiconductors are designed to run off a nominal 28V supply, and this, coupled with the higher efficiency, means that much less supply current is required, making the new amplifier more suited to mast-head mounting than the old modules.
The bandwidth of the new PA is fairly narrow. The PCB has been designed for optimum operation at 1296MHz, and can be used with slightly reduced performance "as-is" at 1269MHz (for satellite uplink use). However, small additional tuning elements are provided on the pcb as extensions to the input and output matching stubs, which allows the amplifier to be optimum at 1269MHz. Optimisation at other frequencies is possible - versions have been produced so far up to 1315MHz..
The PA is realised using a discrete (unmatched) transistor, with matching elements provided on a low-loss ptfe based PCB. Most of the other components are SMT devices.
A coupler/detector has been incorporated, to give an indication of power output.
To date, many amplifers are on the air, with excellent results. Applications include ssb/cw operation at 1296MHz, satellite uplinking at 1269MHz, and ATV in various parts of the band.
We are able to supply ready-made tested prototypes at a price of 165 pounds, plus shipping. These are built directly on a heatsink. For continuous operation, the heatsink needs to be cooled by a small fan (eg 80 x 80mm axial type). Connector options are either SMA or N female. Connector types can be mixed - for example SMA on input and N on output. Please specify connector types and heatsink/chassis plate options.
Typical performance:
Small signal gain [200mW input] 15-16dB
Power output at 1dB gain compression: >30W
Power output with 1W drive: ~30W
Power output with 2W drive: ~50W
Detector output at 40W RF output: ~3mA
Drain current at 1dB gain compression ~3A
Drain current at 50W RF output <4A
First PA prototype mounted on heatsink (click to enlarge)
Latest PA prototype - N connector option in this case (click to enlarge)
Power output v power input (click to enlarge)
Gain v power input (click to enlarge)
Efficiency v power input (click to enlarge)
Power output v Supply Voltage (click to enlarge)