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url link for UK Ham Radio licence Amateur licence EMF (ofcom.org.uk)
Note from Alastair GW0AJU:
I have written vfo controlling software because I could not find any solution to construct a up to date micro-controller digital vfo, so as I was experimenting around with the Arduino platform, I got down to some thoughts and came up with some software for the fellow radio hams to use. I admit things have come a long way, but the bug got to me, so I carried on writing Arduino code for all to use.
The software provided on the website and this blog, is for fellow hams to use as a base model for their projects. The software I have tested impart ( to find if it actually does tune the vfo ) with the Icom R70, building the Arduino test bed with the usual pin wire leads.
To download the Arduino code, link to the code can be found on my website www.radiohamtech.com, from the menu tab "downloads". This will take you to the arduino code download page for the arduino coding previously available from my google drive account. I have found that it is not so easily achieved to download the code from the google drive, to avoid problems I have made available the text code of the Arduino coding on my website.
An additional program just added, is the lower tri-band vfo software based around the silicon labs si5351 dds board, found from many places as well as adafruit. The devices drivers for the si5351 and the ads1115 adc board around found on github, link from which can be found via the adafruit website. The touch screen drivers came from the Sainsmart website.
From watching a youtube video postings, I have done similar with the si5351 to provide both the vfo and bfo source signals, and as before the CW tx is the vfo placed onto the dial frequency for transmission, while for Rx CW mode, the vfo is placed high for a 9MHz I.F., howver for SSB operation, the vfo is stationary as the 9MHz I.F. produces the SSB signal. A single side band crystal filter for 9MHz operation can be source from the GQRP magazine and website, but for good manners, please join the GQRP for there magazine.
For those who are using the Bitx 40m kit, adjust the si5351 lower tri-band code for a 12MHz I.F., by changing the 9MHz fnumber value or a 12MHz value within the arduino coding. One suggestion may be to use the band switching led panel of the tri-band software to band switch the input and output filtering of the Bitx board, thus allowing a 160m, 80m and 40m QRP operation from one BItx board.
If one assumes that the Arduino adc port value of 500 out off the 1024max reading is used as an S9 signal, then an idea for an AGC circuit, the LM1350 agc chip has a 50dB AGC dynamic gain range, by using the "active bridge v3 code", an signal "S meter" reading would be up to S9 + 6dB. However if two LM1350 chips are connected in series, a 100dB AGC dynamic range would result. To read this signal range, use the active bridge v4 code, as this arduino code uses the 4 channel 16bit adafruit ADS1115 adc board, which would allow the arduino code to read up to S9 + 44dB. However, a warning here that the agc voltage from your agc deriving circuit voltage would need to stay within 4Volts with the ADSS1115 board with its current code setting. However the measurement range of the adafruit adc board is changeable to user needs in arduino code.
However if the 10bit Arduino adc port measured value of 50 is used as the 50uV RF input, which would equate to an S9 signal, by adjusting the code on the "active bridge v3 code", then the max "S" meter reading would be S9+26dB for a single LM1350 agc chip. For two AGC amplifiers in series, then the around 100dB range would indicate a reading of S9+62dB, using a 16bit adc circuit.
A moving bar graph type meter is now listed as the "Dual mode active bridge". This version has both the bar graph for signal and power, and by a switch enable, the display can be changed to that of the active bridge mode, showing Rx, Tx and swr as well as the effective antenna loading as a transmission line cable equivalent. The original lcd bar graph previously listed has been deleted, the bar graph was in-correct on its metering to the values stated as its measurement. The new version "dual mode active bridge", has corresponding bar graph mode plots equals the stated values on the active bridge mode.
Have fun!
Many Thanks
Alastair GW0AJU
Arduino drivers:
https://github.com/adafruit/Adafruit_ADS1X15
https://github.com/etherkit/Si5351Arduino
http://wiki.sainsmart.com/index.php/3.2%22_TFT_Touch_LCD#Using_the_LCD:_UTFT_example_sketch
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