Hi
I'm reaching out to the experts for advice, guidance & help please.
The Hermes Lite 2, "HL2", is a DDC/DUC SDR transceiver - - which can output upto 5W PEP RF.
The RM Italy BLA-350 plus, "Linear", is a 400W PEP HF Linear amplifier - with an input drive of upto 10W.
At 5W RF out from the HL2, the BLA-350 puts out about 130W PEP.
So, the problem is how to get the output of the HL2 from 5W to 10W to drive the BLA-350 ?
The solution looks like it might be to use the QRP Labs 10W Linear Amplifier - - “PA”, to generate the 10W required to drive the BLA-350 to full power output.
The first step is to reduce the 5W HL2 output down to 25mW acceptable to the PA, a T attenuator giving about 25~26dB attenuation should reduce 5W to around 25mW. The T attenuator would comprise of 2 x 45 R in series with a tap to ground of 5.6R to yield an attenuation factor of -25.11dB - . The HL2 does have a 17dBm fixed output intended for transverter operations but one would still need to arrange for receive signal switching; the approach I've taken I think permits me to use the drive level in the HL2 to control the output power from the Linear.
During receive, the PA, and attenuator must be bypassed; during transmit, the receive chain needs to be bypassed, relays are used to carry out the required switching operation when PTT is closed /connected to ground by the HL2.
Hopefully the schematic below describes what I think needs doing with sufficient clarity.
I would really appreciate your advice, guidance, help, suggestions for improvements, and of course correct my errors.
Very Many Thanks, 73
Peter - GM8JCF
