Uncategorised

Details: Written by: Jari Ojala; Category: Uncategorised; Published: 25 December 2025; Hits: 23

LDMOS Linear amplifier control system.

LDMOS amplifier control board, where all fast protections are built in hardware, only alarm notifications are software-based. This ensures fast protections regardless of the software.

The Arduino development platform has been used as the "smart" one. The controller board is compatible with two Arduinos, DUE and Giga Wifi R1. When using the Arduino Giga platform, the amplifier has a WiFi connection and remote control.

The user interface is a Nextion 5" or 7" touch screen. A visual and easy-to-use graphical user interface is built into it.

There is a Java-based web page for remote use. The page shows all essential information about the amplifier's status, and the most important controls can be made using a browser.

The controller board supports one, two and four LDMOS module amplifiers, the settings menu allows you to select how many modules are in use, each current is measured separately. In addition, several different power and current ranges can be selected from the menu for the bar graph, making the displayed values more visual. The board also has historical data, including TRX relay switching times, time in standby mode and time on the transmitter. There is also a so-called trip meter for standby time, i.e. a user-resettable time counter.

A 0-3 dB programmable attenuator can be connected to the RF input, which can be used to change the level of the incoming signal on a band-by-band basis. To avoid damage, you can select which bands the amplifier will operate on.

WiFi settings are in their own menu, where you can configure the settings to match your network environment. Remotely using a browser, you connect using the selected IP address.

Main operating view

Four layer PWB (Kicad 3D)

PWB and Arduino board (DUE or GIGA)

Four module view

Two module view

One module view

Main setup page

WiFi setup page

Remote view

Details: Written by: Jari Ojala; Category: Uncategorised; Published: 04 July 2025; Hits: 3565

Details: Written by: Jari Ojala; Category: Uncategorised; Published: 19 June 2025; Hits: 3941

Pin	Description	Remarks
1	50 V on active LOW	Output open collector
2	Shutdown active LOW	Output open collector
3	Fault reset active LOW	Output max. 3.3 V
4	GND
5	GND
6	Current meas module A 0-10 V	Output analog
7	Over current module A active LOW	input max. 3.3 V
8	Shutdown active LOW	Output open collector
9	Current meas module B 0-10 V	Output analog
10	Over current module B active LOW	input max. 3.3 V
11	Shutdown active LOW	Output open collector

J1 Connector Vds control module A-B

Pin	Description
1	50 V on active LOW	Output open collector
2	Shutdown active LOW	Output open collector
3	Fault reset active LOW	Output max. 3.3 V
4	GND
5	GND
6	Current meas module C 0-10 V	Output analog
7	Over current module C active LOW	input max. 3.3 V
8	Shutdown active LOW	Output open collector
9	Current meas module D 0-10 V	Output analog
10	Over current module D active LOW	input max. 3.3 V
11	Shutdown active LOW	Output open collector

J2 Connector Vds control module C-D

1	GND
2	BIAS ON module A Switch bias voltage on. PTT delay 20 ms	Output Active LOW
3	+12 V	Output
4	LM35_A analog in	Input
5	+5 V LM35 Vcc	Output
6	GND
7	+12 V	Output
8	BIAS ON module B. Switch bias voltage on. PTT delay 20 ms	Output
9	GND
10	NC

J3 Connector bias module A

1	GND
2	BIAS ON module C. Switch bias voltage on. PTT delay 20 ms	Output Active LOW
3	+12 V	Output
4	LM35_B analog in	Analog Input
5	+5 V LM35 Vcc	Output
6	GND
7	+12 V	Output
8	BIAS ON module D. Switch bias voltage on. PTT delay 20 ms	Output
9	GND
10	NC

J4 Connector bias module B

1	Reflected 0-13 V (400 W à2,826)	Input
2	Forward 0-13 V (3200 W à7,994V)	Input
3	GND

J5 Connector Power sensor

1	Vds scaled	Input
2	GND

J6 Vds scaled 0-3.3 V

1	+12 V
2	Relay (open collector)	Output

J8 Connector J8 RTX-relay control

1	PTT active LOW	Input
2	GND

J7 Connector PTT

1	GND
2	Serial RX TTL 5V	Input
3	Serial TX TTL 5V	Output
4	+5 V 1.5 A

J9 Connector Nextion display

1	NC
2	GND
3	PTT	Input
4	TX INH	Input
5	GND
6	NC
7	BAND A	Input
8	NC
9	BAND B	Input
10	NC
11	BAND C	Input
12	NC
13	BAND D	Input
14	GND 1
15	TX INH	Input
16	NC

J10 Yaesu Linear port

1	+12 V
2	160 m (open collector)	Output
3	80 m (open collector)	Output
4	60 m (open collector)	Output
5	40 m (open collector)	Output
6	30 m (open collector)	Output
7	20 m (open collector)	Output
8	17 m (open collector)	Output
9	15 m (open collector)	Output
10	12 m (open collector)	Output
11	10 m (open collector)	Output
12	NC

J11 LPF control

1	FAN+ 5-12 V temperature controlled A	Output
2	GND

J12 FAN power

1	FAN+ 5-12 V temperature controlled A	Output
2	GND

J13 FAN power

1	FAN+ 5-12 V temperature controlled A	Output
2	GND

J14 FAN power

1	FAN+ 5-12 V temperature controlled B	Output
2	GND

J15 FAN power

1	FAN+ 5-12 V temperature controlled B	Output
2	GND

J16 FAN power

1	FAN+ 5-12 V temperature controlled B	Output
2	GND

J17 FAN power

1	+12 V 2 A	Input
2	+5 V 500 mA	Output
3	+3.3 V 500 mA	Output
4	GND

J18 Power connector

1	Power signal 0-3.3 V	Input
2	GND

J22 Harmonic load power sensor

1	Closing relay max 1 A	Output
2	COM	Output

J23 Vds Power supply control

1	REFL	Input
2	REFL	Input
3	FORW	Input
4	FORW	Input
5	GND
6	GND

J24 WaveNode sensor MiniDIN

1	+12 V
2	Input ATT control 1 (open collector)	Output
3	Input ATT control 2 (open collector)	Output
4	Input ATT control 3 (open collector)	Output
5	GND

J25 Input attenuator control

1	Forwarding power 0-10 V	Input
2	Reflected power 0-10 V	Input
3	GND

J26 LPF-fault sensor

1	Shutdown active LOW	input
2	Input over power detected active LOW	input
3	Fault reset active LOW	output
4	GND

J27 Input over power protection

1	BAND signal 0-10 V	Input (ICOM band voltages)
2	GND

J28 ICOM band selector

1	RXD	Input
2	GND
3	ESP_PD (power down)	Output
4	NC
5	NC
6	NC
7	+3V3	Output
8	TXD	Output

J29 ESP32 Wifi module

J19	+3V3 to Arduino	No Connect
J20	+5 V to arduino	No connect
J21	+ 12 V Vcc to Arduino	Closed (feed 12 V to Arduino)

Jumpers (set arduino voltages)

Calibration

Trimmer	Adjustment	Cause
R9	Over Power	Set point to shutdown amplifier
R10	Ids A Calibration	Display bar level setting
R19	Ids B Calibration	Display bar level setting
R23	Hi SWR Calibration	Set point to shutdown amplifier
R29	Ids C Calibration	Display bar level setting
R30	Ids D Calibration	Display bar level setting
R31	Vds measurement calibration	Display bar level setting
R32	Vds Upper limit calibration	Set point to shutdown amplifier
R75	Max temperature A-sensor	Set point to shutdown amplifier
R76	Max temperature B-sensor	Set point to shutdown amplifier
R113	LPF Fault SWR detection	Set point to shutdown amplifier