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 Amateur Radio Frequency Measurements:


 0-30MHZ RF Power Measurement:


 Dual Channel LCD SWR Meter SWM3 USB


Project by:

Antonio Alfinito / I2TZK

Frank Dziurda / K7SFN 

Dinesh Gajjar / VU2FD


Dual Channel LCD SWR Meter SWM2 was a great success. Hundreds of Radio amateurs built it with success. With more and more feedback pouring-in and many demanding an SWR Meter with USB built-in, Tony/I2TZK decided to go for an SWR meter which is True USB and USB Powered. 

SWM3 is an USB CPU Powered by USB port. Based on Microchip's PIC18F4550 40DIP Chip, all what that we require was this a PIC and very few components. FTDI type SOIC chip for USB Communication is no longer required as 4550 already has USB communication. 

This new CPU is developed keeping in mind existing HF and VHF Bridges with which its fully compatible. This makes it ready to use USB Powered CPU for ham station/shack.

Firmware and PC Software (WinXP/WIN7) for SWM3, Dual channel LCD SWR Meter presented here is developed by Antonio Alfinito / I2TZK for the ham community. 

Purpose of this project is to encourage radio amateurs to build their own SWR Meter at a low price.  

I2TZK PC Software (WinXP/WIN7) & PIC Firmware V2.0 for SWM3 has achieved following design task:  

Simple single Micro Controller with built-in A/D converter (PIC18F4550)
Interchangeable HF Simple, HF Dual Scale and a 144MHZ RF Bridges
CPU Unit has:
2 x 16 LCD with Back light control  
Stable Reference voltage.
D9 Connectors for Bridge
SWR, FWD, POWER and Actual Power to antenna   calculations/Display.  
Bargraph mode for SWR & Forward Power  
Simple detection of the port where the LCD Unit is connected. Goes to Stand Alone mode if mode switch is "On" 
Graphic interface to display data read from the LCD Unit: Digital and Analog Meter, Compact and Test window.
Emulate the buttons of the LCD Unit and send relevant commands to switch the unit to any operative mode.
Configure the computational parameters of the LCD Unit (CPU)
Collect data for statistical analysis
Works without a PC as a Stand alone with external 5V supply from USB port or adapter.


PC Software & Data-logger views:
Software V2.01 (WinXP/WIN7)  


Click to enlarge

Project Bases:

Project is developed on two double-sided PTH board. The first one is CPU board where LCD, Regulator and Back Light Controllers are located. This board receives pure DC level from sensor (Bridge) board for calculation & display.

The second board is RF Bridge, where power from your transceiver comes in and goes out to antenna. Varity of Bridges are offered. Please refer to capability of each Bridge in related documents.

SO239 types of connectors are used but Type N may be offered as an option.  

Kit is intended for experienced Radio Amateurs. 

Although, rated at 100W HF, this meter & bridge works very well at a KW  or two, on all bands. Readings were very accurate compared to commercial SWR Meter. 

A simple powder coated case for CPU and bridges (HF Simple, Dual scale & VHF) are now available and offered free of charge with kit or assembled. 


 SWM3 Dual Channel LCD RF Power Meter CPU Unit:

Click the image to enlarge

 Mode Switch for Stand Alone / PC Operation

Click the image to enlarge

Free Powder Coated Metal Case for HF Simple, Dual Scale and HF Balanced Bridges 
Click above picture to visit BHF/VHF Bridge Projects

 Available Bridges for SWM3 CPU
HF Simple Bridge:

Click to visit project page

HF Dual Scale Bridge:

Click to visit project page

HF Balanced Bridge 100W:
Click picture to visit project page
 SWM3 Schematics, Tech Details & Parts List:


SWM3-CPU Tech Info Doc. 0-500MHZ RF Sensor Document
SWM3-CPU Schematic & Parts List 0-500MHZ RF Sensor Document


HF Simple Bridge Schematic & Parts List 0-500MHZ RF Sensor Document
HF Dual Scale Bridge Schematic & Parts List 0-500MHZ RF Sensor Document
HF Balanced Bridge 100W Schematic and Parts List

0-500MHZ RF Sensor Document

Calibration procedure for HF Bridge by Frank/K7SFN

0-500MHZ RF Sensor Document


Must Read: A very nice setup doc by an experienced user/kit builder

0-500MHZ RF Sensor Document

Review by Camradio Group

Pictures of SWM2 Completed by DL7WA

Print template included



 SWM3 PC Software, Firmware and Documents
I2TZK Web Site


SWM3 SOFTWARE 2.06, PIC4550 Firmware V2.06 and Documents

Note: Present kits are supplied with this firmware   
 Last Version Firmware & PC Software

SWM3 SOFTWARE, PIC4550 Firmware V2.05 and Documents

  Previous Version software and firmware: V2.0
I2TZK PC Software (WinXP/WIN7) for Dual Channel SWR Meter  V2.01

SWM3 PIC18F4550 Firmware V2.00 (Full & Update)

SWM3 Microchip USB Drivers and Document


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For online payments, shipping charges will be added on secure web page, from $5.00 upwards for Registered Air Mail. (based on total value (Multiple kit purchase) of the KIT/Assembled)

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Buy From 2CO     

SWM3-CPU Kit  Being Revised
SWM3 Kit Parts(CPU) List
No bridge is supplied with SWM3 USB CPU KIT or assembled. Buy a suitable bridge from the list below.



HF & VHF Bridges:
Bridges are not calibrated and need to be calibrated using standard procedure.
SO239 Standard. Type N Available

HF Balanced Bridge KIT with free case 35.00

2CheckOut.com Inc. (Ohio, USA) is an authorized retailer for goods and services provided by Fox Delta.
Kit Parts List

HF Dual Scale Bridge KIT with free case 39.00

2CheckOut.com Inc. (Ohio, USA) is an authorized retailer for goods and services provided by Fox Delta.
Kit Parts List



2CheckOut.com Inc. (Ohio, USA) is an authorized retailer for goods and services provided by Fox Delta.


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