ADRIAN KNOTT PROPOSES TUNED VLF ACTIVE ANTENNA

Hi to all! Today I found a very interesting project that using a small whip for hear the long VLF waves. Adrian Knot says that with this simple and inexpensive system you have good results, but suggests the using outdoor far from electric sources.
References: (http://www.hard-core-dx.com/nordicdx/antenna/special/vlfactive.html)

RECEIVE VLF: SOME PROJECTS BY TECHLIB

Receive VLF is not very simple. Today the pc sound card help us to this aim but this is not the only way. TechLib reports some projects to approach the problem easily also without using pc!
The projects are collected to TechLib page. Follow only one simple sound card receiver.

AJ4VD DENTIST BY DAY, HAM BY NIGHT PLAY WITH HELLSCHREIBER

This post describes a project  designed by Scott AJ4VD which transmits strings of data from a microcontroller to a PC’s screen using audio beeping in a special mode called Hellschreiber. Although these days it’s almost exclusively used by amateur radio operators, This is a cool microcontroller project! The result can be accomplished with a microcontroller and a speaker as a transmitter and a PC with a microphone as a receiver and decoder, or with actual radio equipment (even toy walkie talkies) by transmitting the tones over modulated radio frequencies for long distance communication!
Reference: http://www.swharden.com/blog/2011-08-05-i-before-e-except-after-hellschreiber/

PA3HCM PROPOSE AUTOMATIC ANTENNA TUNER USING ARDUINO

Ernest PA3HCM connected an old SWR meter to Arduino board. Furthermore Ernest build a simple L-tuner with a fixed coil and a rotating capacitor. The capacitor is driven by a servo, also connected to the Arduino. By doing a full sweep with the capacitor, the Arduino tries to find the position with the lowest SWR. After the sweep it turns the capacitor to that position. You can view the video below to see the tuner version 2 in action. Mind the SWR meter (right needle) in the back while the capacitor is rotating.


References: ( http://ernest.utreg.net/?page=arduino-tuner )

ARDUINO CAT INTERFACE FOR ANTENNA SWITCH BY ON7EQ

An ideal tool for connecting your IC-706 or IC-7000 to more than one antenna and having them switched automatically.   You could as well use it to drive a 5 bands BPF ... or  develop an antenna tuning unit, a magnetic loop variable condenser stepper motor drive etc ...
This sketch will readout on a 2x 16 characters LCD display the frequency of any ICOM transceiver by reading the CAT line (the device acting as a listener only, the transceiver is set to 'CAT TRANSCEIVE' mode to broadcast data) and switch 5 + 1 antenna's  (or band pass filters... ) according to band.
Up to five digital outputs are to be interfaced with relays, the sixth position is 'no relay energized'.  CAT activity will be displayed in the top row, on the right side (a small 'c' will show up when valid CAT data is received).  I used 9k6 as my SPE power amplifier runs at 9k6 as well. The ARDUINO board is simply put in parallel with it.
The matrix can be programmed with 2 push-buttons (scroll left or right), the values are permanently stored in EEPROM after a small delay, once the choice is definitive (this to avoid too many write cycles to EEPROM). When the new setting is memorized, a small 'M' will briefly show up on the second line at right.  The switching combination can be different for RX and TX  (reading the PTT line, it will select the right antenna).  In program mode, you have to depress a push button which indicates this is the 'TX' antenna.   In TX mode, no antenna can be changed / programmed with the scroll buttons.

All the settings programmed in the matrix can be cleared if you depress button scroll buttons at startup / reboot.
Read More for arduino code or visit http://www.qsl.net/on7eq/projects/arduino_ant_matrix.htm


Reference: ( http://www.qsl.net/on7eq/projects/arduino_ant_matrix.htm )