Wednesday, November 14, 2018

DATV Predriver Amplifiers

Having built the BATC Portsdown DATV transmitter I realised I needed amplifiers between it and my final amplifiers. The neatest solution would be to use Mitsubishi Power Modules. I managed to obtain some

I used RA07H0608 on 4m, RA08H1317M on 2m, RA07H4047 on 70cm. Each could produce around 7W. I managed to source some G4DDK PA/LPF PCB onto which these modules would fit.

Each amplifier was mounted in a diecast box, with an SMA input connector (to match the Portsdown output connector) and BNC output connector to match the following amplifier. A BTS4140 high side switch IC driving a 78L05 regulator was used to provide switched 5V to bias the module. Switching was achieved with an earth on transmit signal from Portsdown. The amplifier also provides an earth on transmit output to switch the following amplifier.

Each module produces 7W output with all harmonics over 55dB down on the fundamental

  

The Fourth amplifier, the one on the right, is a Chinese broadband 2 to 900 MHz 2.5W amplifier from Ebay, that may come in useful one day!

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