pa

Power Amplifier with Interface to Hermes Lite 2 (HL2)

Frontpanel

• Push-Button for turning on 50V supply
• Switch to select StandBy/Operate
• Green LED for 50V indication
• Dual Color LED for Operate (green) and Tx (red)

Connectors

• APP 75A 50V Supply
• APP 15A 12V Supply
• RJ45 LAN Web Server for monitoring
• DB9 Band Selector Input
• 3.5mm (optional)
• Chinch PTT
• PL259 Input (< 5W)
• PL259 Output
• SMA Pickup for predistortion (optional)

Amplifier Board with 10 dB Attenuator

• input circuit just attenuator and a 1nF capacitor (seems that nxp has not finished the reference circuit for 13.56MHz)
• attenuator with 3 resistors (100-75-100 Ohm)

PCB

• KiCad design (1x MRF300AN / 5x MRF101AN)
• boards from jlcpcb.com
• first test with tiny MRF101AN board - output power abt. 120W

Control and Protection

• Control board with CPLD (LC Technology MAX II EPM240)
• PTT, Rx/Tx sequencing, band selection with driver, LEDs, Buttons, FAN PWM
• seperate over current protection board with BTS50085 (BTS660) set to 8A

Filter, SWR and Monitoring

• Low-Pass-Filter from W6PQL (only 10, 20, 40 and 80m assembled)
• 160m not assembled / 6m relays used for Rx/Tx
• 2 Coupler from DJ0ABR to protect amplifier from High SWR (filter and antenna)
• orange pi one (small die cast housing) with ADC (Abio Card) for monitoring Current, SWR and temperature

Hermes Lite 2

• standard die cast housing
• thermal contact to PA transistors via copper tape
• band select just used wires from P1-P7 and GND to DB9 (level shift with opto coupler in PA)

Station

• HL2 with amplifier and LDG AT-200Pro II Tuner transmitting at 14.1MHz
• Output Power is at the limit of LDG (240W @ 45V/7A)
• Power Supply is Cisco Catalyst 6000 6500 Sony APS-162(ID) 1300W PSU P/N 34-0918-02 8-681-326-21
• Output voltages (3.3V, 5V, 12V and 42V/27.5A (can be set to 45V with trimmer))

MRFE6VP61K25H PA

• Amplifier with MRFE6VP61K25H Transistor
• PCB from W6PQL - circuit "shipped after June 2017" with small modification
• R15 not installed, C25/26 220pF, L1/2 Wuerth 74270115 (9 Turns)
• 10dB attenuator at the input

Measurements

• HL2 with SDR Console 3.0.16 2-Tone @ 0.7 (for clean output with 5W PA). 2.6W IM3 abt. -40dBc
• HL2 with PA - Gain of PA about 17dB (27dB Transistpr - 10dB attenuator). 130W IM3 abt. -38dBc
• measurements with Red Pitaya receiver and Quisk software