Showing posts from January, 2019

43′ Vertical Final Install Pictures

  43′ Vertical Final Install Pictures Filed in Antennas on Jan.22, 2019 I received an email from a follower that had questions about my final configuration of the matching network for my 43′ vertical.  I promised him I would take some pictures of it the next time I was up at the Ranch, so I did that yesterday. A couple of them are a little blurry, but there are enough to see what is connected to what.   43′ Vertical Matching network As you can see above, I have lots of radials installed beneath the vertical.  There are 32 of them, each 40′ long, mostly buried an inch or two underground. After troubleshooting the matching network, I never repaired the burned-out choke on the transmitter end of the bias tee network.  Instead, I used a length of cheap RG-6 cable, totally separate from the RF path, to carry the +/- 12 volts to energize the appropriate relays for the different bands.  It enters from the bottom through an f-type connector installed between the two terminal stri

Thunderbird Hamfest 2019

  Thunderbird Hamfest 2019 Filed in Station on Jan.20, 2019 One of my favorite hamfest did not disappoint me this year. I always find good bargains on tools and equipment at this hamfest. My first purchase was an MFJ-267 1KW Dummy Load/Wattmeter.  The seller had all of his equipment priced at the exact same point – $68.00.  That seemed a good enough price that I did not even haggle over it.  He said he just needed to get rid of some stuff… I got it home and hooked it up, and it appears to work, though may need a calibration.   MFJ-267 Dummy Load/Wattmeter My next purchase was a 250 Watt dummy load.  The seller of this item told me that he makes and sells these on Ebay for $35 or so.  He was selling them here for $30, with a N to PL-259 adapter included.  It looks like good workmanship, so I bought one.  He says it will do 100 watts continuous, and 250 watts for 1 min on, 5 Min off.   Dummy Load front   Dummy Load Back Next, I found some old HP AC voltmeters for sale at $5.

An Alternative BMP280 Module with the Arduino

  An Alternative BMP280 Module with the Arduino Filed in Microcontrollers on Jan.20, 2019 Besides the Adafruit BMP280 breakout module, I found a cheaper alternative on amazon for $5.88. This module is sold by a Chinese company named DiyMore.  It is a 3.3v only breakout, so it has no onboard regulator or level translating circuitry.  So you must be careful to only use a 3.3 volt supply with it.   DiyMore BMP280 This module arrived in a package marked as a BMP085, which led to some confusion, but I eventually discovered that it is indeed a BMP280 (Device ID=58), which supports measurement of Atmospheric Pressure, Temperature and Humidity.  Altitude may be calculated from the barometric pressure, assuming you know what the local pressure or altitude was on startup.   DiyMore BMP280 Back side As you can see, it breaks out all of the pins necessary to communicate with the device via I2C or SPI mode. There was no documentation included with the board, and nothing on the intern

Arduino and the BMP280 Pressure Temperature Module

  Arduino and the BMP280 Pressure Temperature Module Filed in Microcontrollers on Jan.18, 2019 Next up in my Arduino research is the BMP280 pressure/temperature module. This is a device manufactured by Bosch, and is ideally suited to high altitude balloon atmospheric measurements. The bmp280 datasheet has many details about the device.  Each module based on this device will have its own quirks, but they seem to generally follow the datasheet for functionality. Major differences noted between modules are the inclusion or lack of level conversion, ie 5v to 3.3v.  Since the device runs on 3.3v, if you want to use it with most Arduinos at 5v, you will need to check that the module includes a 3.3v regulator and level conversion scheme. If there is no voltage conversion on the module, you should only use it with 3.3v based Arduinos, such as the Due. The Adafruit module that I selected does include the necessary voltage conversion circuitry.  So it may be run on either 5v or 3

Freeduino RBBB and the SD Card Reader

  Freeduino RBBB and the SD Card Reader Filed in Microcontrollers on Jan.17, 2019 The next board to be tested with the SD Card Readers is the Modern Devices RBBB (Really Bare Bones Board). This appears to be similar to the Arduino Duemilanove that we tested in a previous post, in that it uses the ATmega168 chip.  However, the RBBB does not have a built-in USB interface, nor a LED installed on pin 13. It is a small form factor, like the Arduino Nano, with pins spaced to be placed on a breadboard. I didn’t have much hope for using this board with the SD Card Readers, as the Duemilanove failed due to memory constraints. I started off with an inventory of the parts.  Everything that was promised was accounted for.   RBBB Parts I populated the board as detailed in their instructions…     Populated RBBB Then cleaned off the solder flux with alcohol.     Clean RBBB Next, pushed the board down onto my breadboard and hooked up an FTDI USB to rs-232 converter.  It simply plugged strai

Arduino Due and the SD Card Reader

  Arduino Due and the SD Card Reader Filed in Microcontrollers on Jan.16, 2019 The next board to test with the SD Card Readers is the Arduino Due.   Arduino Due This is a little different sort of beast, more powerful. But there are some differences with other Arduinos that can get us in trouble. Differences between Due and the Mega: Microcontroller AT91SAM3X8E (Due) ATmega1280 (mega2560) Operating Voltage 3.3V 5V Input Voltage (recommended) 7-12V 7-12V Input Voltage (limits) 6-16V 6-20V Digital I/O Pins 54 (12 provide PWM output) 54 (15 provide PWM) Analog Input Pins 12 16 Analog Output Pins 2 (DAC) 0 DC input per Pin 3 – 15mA ( see chart ) 40 mA Total DC Output Current 130 mA 200 mA DC Current for 3.3V Pin 800 mA 50 mA (up to 150 mA, if no FTDI) DC Current for 5V Pin 800 mA 200 mA Flash Memory 512 KB all available for the user applications 128 KB (4 KB used by bootloader) SRAM 96 KB (two banks: 64KB and 32KB)