Archive for the ‘Amateur Radio Projects’ Category

AllStar Micro Node with Baofeng BF-888s

Sunday, January 18th, 2015

This has been done before so lot’s of credit to kp4tr and w0fcm!  For my Micro Node, I am using a modified audio fob, a Baofeng BF-888s, power hub, and wireless FOB (optional).  I also added a push button for the power for the BeagleBone Black for powering down. This is located on the side of the BeagleBone Black case.  The case is an all metal case from Logic Supply.  The power converters are from E-bay and allows a high range of input voltages and reduces the voltages for the BBB (5v) and BF-888s supply (3.8V).  The modified Audio FOB is a Star Tech USB device which has a small board extension for the PTT control. Note that I had RFI issues with the stock antenna getting into the audio usb device. I use an external antenna without any RFI issues.




Allstar Nano Node Construction

Thursday, December 18th, 2014

I have a preliminary schematic of the Allstar Nano Node.  This is still under construction and I will be adding additional construction pictures as I progress through this project.

Nano Node - USB FOB/Transmitter Module Schematic

Nano Node – USB FOB/Transmitter Module
Schematic (updated 12/20/2014)

These modules do need additional filtering. I will be posting a link or provide additional information regarding the output filter.

Nano Node using Modified USB Audio FOB and an 818 UHF Module.

Nano Node using Modified USB Audio FOB and an 818 UHF Module.

The audio FOB shown above was modified based on the following article by Doug, WA3DSP:

I mounted it above the board using cut resistor leads to raise the board above the proto-board.  This was similarly done with the transceiver module.  There are small copper pads that I made with my punch from a single sided circuit board to insulate the PTT and COS lines and make a convenient junction point.

The three pin edge connector is for programming the module.

Here is the final result:



Doug, WA3DSP, has a 818 transceiver module page. His module  mounted in an Altoid  style tin and uses a 9 pin connector to interface with the URI – USB Radio interface.  He also has information on filtering. The following is a link to his page:

URI USB Radio Interface Link:

Audio FOB Modification Links:

KP4TR – great idea for a simple enclosure:

Final Notes

I have been using the 818 transceiver modules for a while.  One thing I noticed is that the receiver in the modules  “crackles” with multi-path signals as if the receiver AGC is clipping.  It sounds like a bad mic or connection.  This occurs on all the modules that I have tested and does not matter what radio is transmitting to the module. I can’t explain this issue and I have also seen the same issue on my Baofeng UV-82 transceivers during receiving.  The “crackling” is very noticeable and bothersome and does not matter how the module is programmed or if filters are enabled or disabled.

DRA818/SA818 Module Programming Software

Thursday, December 4th, 2014

I have written a simple program to configure the DRA818/SA818 RF modules. It supports the 3.3V level FTDI USB to serial devices.  I believe that the SA818 modules can be programmed at the 5V TTL levels, but I have not tried this.

Below is a diagram of the minimum configuration to program or set the module for use. Note, +VCC is 3.3V for the DRA818 Modules.


This program is written in python2 and is configured to use a FTDI USB to Serial Adapter. It works but it has very little checking on the value/range syntax. I have tested these programs  on Linux systems running both Lubuntu and Mint as well as  on BeagleBone Black computer.

The program requires phython2 and pyserial module.  The module information on pyserial can be found at:

Arch Linux

 The packages are python2, and python2-pyserial.  To install, use the following command:

  • pacman -Sy python2 python2-pyserial


A package is available under the name “python-serial”.  Note that some distributions may package an older version of pySerial. Note that some distributions may package an older version of pySerial.

  • sudo apt-get install python2.7 python-serial

For the BeagleBone Black, I’ve included a simple install script that will
install any package dependencies.

There are no syntax checking for the value format  at this time. When prompted for values,
pay close attention to the format of the data.


To install the software, download either the zip or the tar zip’ed file  from the end of this article.  If you are using the BeagleBone Black, there will be an script. This will install the python package dependencies and copy the two programs, 818cli-prog and 818-prog, to /usr/local/sbin.

For others distributions, you will need to manually install the python package dependencies (as shown above), and copy the programs from the “src” directory to the desired location. I would recommend /usr/local/bin. You may run into permissions issues with the usb/serial device if you are running these programs  with standard user permissions. (more on this later).

Program Syntax

Value Syntax

Frequencies should be entered in MHz as XXX.YYYY using a  four digits suffix. For example, 446.05 should be entered as “446.0500

Likewise, CTCSS/DCS values should be entered with four digits, 0022 or 0754N. See
below for more details.


The CTCSS tones should be entered using all for digits, for example CTCSS
tone 181.8, should be entered as 0020.

DCS Codes

The format needs to be full three digits plus an “N”. For example, DCS code 7

should be entered as : 007N

Inverted DCS Codes

The format for inverted codes is the same as DCS codes except instead of an “N”
you change it to “I”. For example, DCS code 7 inverted, would be entered as:

Here is the program.  The script is meant to be used for the Beagle Bone Black.  It requires python2 and py-serial.  I have added a non-interactive version to allow command line programming without interaction.  This is included in version 12 below:

Latest changes include channel spacing and updated 818cli-prog help.

Moxon 6M Antenna

Tuesday, June 18th, 2013

I have been working on building a Moxon antenna for 6 meters.  I am using the similar design style as K3NG antenna (  with some minor differences.

Like K3NG’s antenna, the poles are made from snow plow marking poles.  I put super-glued spacers on the ends with holes to allow the wire to pass through.  I then bent the poles upward so that  the wire so that the wire tension is always maintained and at the measured distances based upon the Moxon calculator was obtained.




moxon_1 moxon_2

AllStar Weather Scripts

Tuesday, April 9th, 2013

I was asked to see if I could port my Weather Scripts over to AllStar Nodes.  I have created a tar ball.  This will create a directory called “Weather” and should be extracted under /var/lib/asterisk.  (tar zxf AllStar_WeatherServipts_0.5.tar.gz)


Once extracted, you will find a README.txt file with instructions.  Please be aware that this release is not supported, but I will provide some help if needed as time permits as lately I am extremely busy.  I have this scripts up and running on my Allstar Node 29061 and seems to be solid.  Please refer to the following for more information:

73,  Chris


HF Amplifier 50W 160M-15M

Wednesday, June 13th, 2012

My low cost  amplifier has been modified yet again.  I added a different filter board so that the amplifier will work from 160M through 15M.  The previous version had a home brew filter board covering 80M, 40M, 30M, and 20M.  Instead of re-doing the filter board to include more bands, I decided to go with the following filter board from HF Projects:

HF Projects – Low Pass Filter

Below is an image of the filter board (right-side) and the Arduino amplifier controller (left-side):

50W Amplifier

50W Amplifier

I found that the amplifier started to loose its efficiency above 21Mhz. I also had some issues with the COR/PTT board causing self oscillation; I went with a simpler solution.

Here is the schematic of the Arduino amp controller. Note that this is work in progress:

amp Controller Updated

The latest version of the Arduino amplifier controller  is found here:



PTT/COR Schematic Diagram

PTT/COR Schematic

PTT/COR Schematic



Amplifier for SDR Cube

Tuesday, March 27th, 2012

I have built a QRP amplifier/exciter kit for the SDR-Cube.

5W SDR Amp Home Construction Project SDR (Kit)

This amplifier/filter is reasonably priced and works quit well. You can create your own low pass filters or purchase another filter kit.

I had a previously built kit that Steve Weber designed for his ATA series transceivers which contains a SWR/Power bridge and frequency counter.  I incorporated this board, filter and amplifier in a SDR-Cube accessory  enclosure to finish off the project.

SDR Cube Amplifier

SDR Cube Amplifier/Exciter

My only complaint is that the Amp T/R relays are in the transmit position when powered off which means that if the amplifier is inline and must be power on in order to be connected to the antenna.

Here is a picture of my SDR cube, amplifier and Nue-PSK modem:

SDR-Cube, Amplifier, Nue-PSK Modem

SDR-Cube, Amplifier, Nue-PSK Modem


Updated SDR CUBE Software

Sunday, February 5th, 2012

I have modified the latest SDR Cube software (1.06). This modification included an additional 100 Hz tuning rate and maximum internal CW keyer rate to 50 wpm.

The 100 Hz tuning rate allows you to tune across the band faster preventing stations from being missed at a higher rate of tuning. When you press the “Rate” button, there is an additional rate that you can select.

The internal keyer using the 1.06 software allowed 1 to 100 wpm. The dial was very sensitive when changing speeds. I don’t know of anyone that can send over 50 wpm with an iambic paddle. So for me this was impractical. I changed the speed to allow the internal keyer speeds of 1 to 50 wpm.

I have included a zip file containing the files that have changed from 1.06 release and the hex file needed to program the SDR-cube. See below:


Note:New softaware was just released, 1.08, that has this change and more. Please visit the SDR cube site for more information about this new release.

If you have any questions, please let me know.

Time to Replace the Inverted Vee

Sunday, September 11th, 2011

I have had pretty good luck with my 40/20M fan inverted vee antenna.  I am replacing it before Winter strikes.  I took down the old mast/antenna and found it surprisingly in good shape.

The new antenna is going to include a  17M addition.  This one will be in a spoke configuration instead of one leg on top of the other.  This should help simplify pruning of the antenna.

I was going to replace the 5/8 wave, 440 Mhz antenna on top of the mast, but it was in very good shape. I tried a quick test with a 440 Moxom antenna, but found that the 5/8 still worked better even with the Moxom directivity.

I completed the installation and was pleasantly surprised to see how low the SWR was for each band.  Tuning was only needed for 20M.  With Tuning completed, SWR is 1.5:1 or less for each band.

Arduino IRLP Simplex Node Controller

Monday, July 25th, 2011

One of my first Arduino projects was this IRLP Simplex Node Controller.  This
controller provides several functions:

  • CW ID
  • FAN Control
  • Courtesy Tone

This controller is for simplex IRLP nodes which which controls ID, fan, courtesy tone and a PTT lock (transmit hang) funciton. The CW ID’er  allows the audio to be mixed with the controllers CW ID so that it will only ID when some one is speaking accross the link or when the node is idle.  The controller  frees up the node for extra process scripts for ID’s, Fan Control, and courtesy tones.  With the  PTT Lock (Transmit hang) timer,  the transmitter will be protected by a “hung” transmitter and will force an unkey of the transmitter when a timeout has occured. This PTT Lock will also send an LOCK tone and UNLOCK tone when the PTT line is unkeyed.

The controller is interfaced to the irlp/transmitter via a “breakout board” which allows the user to customize the radio interface.

I have included a breakout board schematic for a GM300 that I use for both simplex node and repeater control even thought I have only tested the controller in simplex operation.

Construction of the controller was done with a proto-boards from Radio Shack.  When building the controller board,  keep in mind that you want to have access to the adjustment resistors,  which was an oversight when I built my original boards.

Some of the modules can be obtain in kit form from the following online stores:

Two boards will need to be built, one for the IRLP audio breakout board which interfaces the audio, PTT, and COS signals to the IRLP Controller board and  another board which contains the interfaces to the Arduino Bare Boards Board.

  Schematic Diagrams


  Board Images