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Messages - Radiotech

Pages: 1 [2]
16
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 19, 2022, 1359 UTC »
I found an error in my datasheet, the efficiency wasnt as bad as i thought  ::)

It turns out that the inductor(8T FT50-43) between drain and VCC impacts the power and efficiency quite a lot! The monofilar had the highest efficiency at 61%, but the trifillar had the highest output in RF-power.


After some tweeking i got nice values

17
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 19, 2022, 0640 UTC »
I took the advice to try to make the construction a bit more compact, and reduce the leads. With the new circuit i also was able to plan a bit better when placing components.



The low output and efficiency could be due to my circuit not having a bifilar or trifilar transformer, most of the designs out there have one. I dont really understand what they doo, they could provide:

1: Voltage transformation to output more power
2: Antenna impedance matching, to provide more power.

The amplifier from QRPlabs below is one example, but there are many others aswell. I tried this with a bifilar wound 8t T50-43 but got a strange effect where the output started low as 1W and slowly over a couple of seconds rose to 2W. Its possible that i did something wrong with mine, i will try to construct a new one, i need some more materials for it though. The QRP labs amp puts out about 50% efficiency and double the output that mine does, so the bifilar/trifilar transformer is probably importent.



One thing that struck me is that the E-class amplifiers i have seen all seem to use a square wave oscillator signal, and my oscillator has a sinewave signal. Could it be that a square wave signal is needed to go quickly to saturation mode?

18
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 18, 2022, 1617 UTC »
Will try to make a board with better layout and fewer/shorter leads, but my hands are too big for the SMD stuff sadly.  :) The board is at least easy to experiment on.

I experimented some with the capacitor that goes from drain to ground on the IRF510, i tried different values, but found that i got the most power without it. Perhaps this is a sign that im operating in C-class. Also removing a few turns from the drain-vcc inductor got me some more power. Almost 3W at 13,8v is pretty ok.

I dont really have any output matching to the 50ohm load, should i try to make a PI network or transformer?


I meassured both Drain-ground(yellow) and Gate-Ground(purple). They seam to be shifted 180 degrees, but i guess that goes for both class C and E. Connecting a probe to the gate of the IRF510 affects output negative.

19
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 17, 2022, 1713 UTC »
Finaly, i made some progress. I get approx 2W at 12v and 8W at 24v.

The oscillator puts 17Vpp into the IRF510, and the bias is adjusted to 2,1Volts. The DC bias at 2,1v is a sweetspot, output quickly drops of both before and after. The drive voltage is 17VPP, Efficiency is about 27-28%

One design i found online had a capacitor from the drain to ground. I just merged the two together, i have no idea what i am doing. My guess is that its operating in class C mode, due to the low efficiency.


Chanel 1(yellow) is voltage into 50ohm dummy load, Chanel 2(purple) is Gate voltage on IRF510.

20
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 15, 2022, 1347 UTC »
I found a couple of usefull pages on how to build an E-class amplifier, and gave it a try. With 12v i get about 1.5W out, so its usefull, but not as high output as i expected.


http://www.wa0itp.com/class%20e%20design.html


Edit:

Also tried this circuit from https://www.researchgate.net/publication/320623200_Notes_on_designing_Class-E_RF_power_amplifiers But i got no usable power from it.


This Class-E stuff is clearly more complex than i expected.

21
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 14, 2022, 1743 UTC »
I have played around some with the cuircuit and discovered that it was the bifilar transformer that made the output power non-stable. Once it was removed(I put a T80-2 with 19 turns) the circuit was very stable, no increasing/decreasing over time. Also made the filter simpler with only one inductor and two capacitors, output waveform still looks nice.

I now get the following power:

30v supply = 4,50W RF output(400mA), efficiency = 38%
25v supply = 3,25W RF output(360mA), efficiency = 36%
20v supply = 2,25W RF output(300mA), efficiency = 37%
15v supply = 1,45W RF output(270mA), efficiency = 35%
12v supply = 0,85W RF output(250mA), efficiency = 28%

After removing some components, there is more room on the board. 4,5W is nice, but it can be a bit tricky to supply when you havent got a variable powersupply at hand.


I will have a look at alternatives to IRF510, that doesnt require as high voltage, it seams to be the most common HF amp on diy projects, cant find many examples with other ones.


22
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 12, 2022, 1428 UTC »
I changed the filter to a Buttersworth of the 7.th order, and it made the wave form look a bit nicer. Found the calculator for it here https://rf-tools.com/lc-filter/

At 13,8v i get approx 2W of RF out, and its farly stable. At 24v however, it starts at approx 4 watts, and during about 3 seconds it increases to 10,5W where the supply goes into current limitation and power stabalises. Is this some kind of thermal run away?

The oscillator drive voltage doesnt increase, its stable. I am driving the IRF510 with a high VPP, so the bias doesnt really do anything, it doesnt affect RF output at least.


Edit: I read that the IRF510 should never have more than 8vpp on the gate, and i have double that. This might be the problem, i will try to power down the oscillator.

Edit 2: Problem percists, even at 7vpp on the gate, power is surprisingly low and unstable at higher voltages. Too high bias and the power increases until current limitation cuts in. Too low, and it doesnt give any output.  1w at 13.8v is a bit low, it should be able to prove higher output.

23
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 12, 2022, 1247 UTC »
I made a 5.th order chebyshev low-pass filter to filter the output, it made the signal look a lot better, but its still not very good looking. Should i use a filter with more components?

I did expect a bit more output power, with 30v of supply i get approx 5,5Watts of output after the low pass filter.

24
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 12, 2022, 1039 UTC »
The IRF510 amplifier works, i get sort off a wave form ;D

Running the oscillator at 8V gives an output of 81vpp. The oscillator puts 16vpp into the gate of the IRF510, and i adjusted the gate bias to just where it starts to draw power.



At first i got no power out from the amp, after a while i discovered that i had wound the T50-43 bifilar 10T the wrong way, once that was solved it worked better!


25
The RF Workbench / Re: Hellschreiber beacon - with some oomph!
« on: February 12, 2022, 0743 UTC »
The circuit is now ready for bias adjustment, and then to do some testing on RF-output vs voltage. There are two voltage regulators on board, 5v for mosfet-bias and the micro controller, and 8v for the oscillator. I got a 0-30v 3Amp power supply, that makes things a lot easier when testing these transmitters.

Im using a T50-43 10T bifilar transformer to the RF-output, it is supposed to impedance match the IRF510 to the 50ohm antenna.

The 400mW drive should be enough, according to the author of the document above, about 500mW is needed to fully drive the IRF510.


I found this http://www.iw3sgt.it/IW3SGT_PRJ/IW3SGT_AMP_LF/ClassDEF1.pdf that describes the different amplifiers in a very easy and understandable way. Its written by NA5N, it made me understand amps better.

26
The RF Workbench / Hellschreiber beacon - with some oomph!
« on: February 10, 2022, 1735 UTC »
I decided to try to use the El Pititico transmitter as an oscillator for a project with some more power than the 750mW i got from the last one. QRP-Labs has a nice HF-amp with an IRF510 that i would like to try.

To get more stability from the oscillator i powered it down to 8v, about 400mW. The voltage will be higher for the PA, to get more RF output. Does anyone know if i should keep the low-pass filter after the oscillator? Or is it enough with the one after the power amplifier?

Also i am redesigning the enclosure, there will be some more heat to dissipate with this alteration, and i need space for more components.

27
The RF Workbench / Re: New 850mW HF beacon,
« on: February 08, 2022, 1756 UTC »
The project is now finnished, a small 40m Hellschreiber 700mW beacon! :) I tried pushing up the voltage to 14v, and got 1W off output but it got really hot. I started thinking about using a down powered Pitico as a oscillator together with an RF power amplifier to get a bit more power from it, that might be a nice project making it a bit more interesting.

Making small electronic projects is a hobby i enjoy, i like tinkering and figuring out how the things work. I am not a RF or Electronic professional, i work in a completely different field. I started this build thread on the Swedish ham radio forum ham.se like QRP pointed out, but migrated it here because i thought more people would enjoy it and have design sugestions.  :)



28
The RF Workbench / Re: New 850mW HF beacon,
« on: February 06, 2022, 1558 UTC »
I finnished the code, it waits for 5 minutes and then transmitts temperature and voltage, if the voltage is above 10v. I am going to have it on my balcony with a dummy load for a few days to find any bugs. I also named the beacon "Gray1"

It transmitts on 7000,5kHz, 40m band, but i would like to move it up a bit before connecting an antenna.

I will try to do some desoldering on the board to lower consumption!

Code: [Select]
int radioPin = A0 ;
int sensorvaluetemp;
int sensorvaluevolt;
int displaytemp;
char buf1[10];
char buf2[10];
int timer;
 
typedef struct glyph {
    char ch ;
    word col[7] ;
} Glyph ;
 
const Glyph glyphtab[] PROGMEM = {
{' ', {0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000}},
{'A', {0x07fc, 0x0e60, 0x0c60, 0x0e60, 0x07fc, 0x0000, 0x0000}},
{'B', {0x0c0c, 0x0ffc, 0x0ccc, 0x0ccc, 0x0738, 0x0000, 0x0000}},
{'C', {0x0ffc, 0x0c0c, 0x0c0c, 0x0c0c, 0x0c0c, 0x0000, 0x0000}},
{'D', {0x0c0c, 0x0ffc, 0x0c0c, 0x0c0c, 0x07f8, 0x0000, 0x0000}},
{'E', {0x0ffc, 0x0ccc, 0x0ccc, 0x0c0c, 0x0c0c, 0x0000, 0x0000}},
{'F', {0x0ffc, 0x0cc0, 0x0cc0, 0x0c00, 0x0c00, 0x0000, 0x0000}},
{'G', {0x0ffc, 0x0c0c, 0x0c0c, 0x0ccc, 0x0cfc, 0x0000, 0x0000}},
{'H', {0x0ffc, 0x00c0, 0x00c0, 0x00c0, 0x0ffc, 0x0000, 0x0000}},
{'I', {0x0ffc, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000}},
{'J', {0x003c, 0x000c, 0x000c, 0x000c, 0x0ffc, 0x0000, 0x0000}},
{'K', {0x0ffc, 0x00c0, 0x00e0, 0x0330, 0x0e1c, 0x0000, 0x0000}},
{'L', {0x0ffc, 0x000c, 0x000c, 0x000c, 0x000c, 0x0000, 0x0000}},
{'M', {0x0ffc, 0x0600, 0x0300, 0x0600, 0x0ffc, 0x0000, 0x0000}},
{'N', {0x0ffc, 0x0700, 0x01c0, 0x0070, 0x0ffc, 0x0000, 0x0000}},
{'O', {0x0ffc, 0x0c0c, 0x0c0c, 0x0c0c, 0x0ffc, 0x0000, 0x0000}},
{'P', {0x0c0c, 0x0ffc, 0x0ccc, 0x0cc0, 0x0780, 0x0000, 0x0000}},
{'Q', {0x0ffc, 0x0c0c, 0x0c3c, 0x0ffc, 0x000f, 0x0000, 0x0000}},
{'R', {0x0ffc, 0x0cc0, 0x0cc0, 0x0cf0, 0x079c, 0x0000, 0x0000}},
{'S', {0x078c, 0x0ccc, 0x0ccc, 0x0ccc, 0x0c78, 0x0000, 0x0000}},
{'T', {0x0c00, 0x0c00, 0x0ffc, 0x0c00, 0x0c00, 0x0000, 0x0000}},
{'U', {0x0ff8, 0x000c, 0x000c, 0x000c, 0x0ff8, 0x0000, 0x0000}},
{'V', {0x0ffc, 0x0038, 0x00e0, 0x0380, 0x0e00, 0x0000, 0x0000}},
{'W', {0x0ff8, 0x000c, 0x00f8, 0x000c, 0x0ff8, 0x0000, 0x0000}},
{'X', {0x0e1c, 0x0330, 0x01e0, 0x0330, 0x0e1c, 0x0000, 0x0000}},
{'Y', {0x0e00, 0x0380, 0x00fc, 0x0380, 0x0e00, 0x0000, 0x0000}},
{'Z', {0x0c1c, 0x0c7c, 0x0ccc, 0x0f8c, 0x0e0c, 0x0000, 0x0000}},
{'0', {0x07f8, 0x0c0c, 0x0c0c, 0x0c0c, 0x07f8, 0x0000, 0x0000}},
{'1', {0x0300, 0x0600, 0x0ffc, 0x0000, 0x0000, 0x0000, 0x0000}},
{'2', {0x061c, 0x0c3c, 0x0ccc, 0x078c, 0x000c, 0x0000, 0x0000}},
{'3', {0x0006, 0x1806, 0x198c, 0x1f98, 0x00f0, 0x0000, 0x0000}},
{'4', {0x1fe0, 0x0060, 0x0060, 0x0ffc, 0x0060, 0x0000, 0x0000}},
{'5', {0x000c, 0x000c, 0x1f8c, 0x1998, 0x18f0, 0x0000, 0x0000}},
{'6', {0x07fc, 0x0c66, 0x18c6, 0x00c6, 0x007c, 0x0000, 0x0000}},
{'7', {0x181c, 0x1870, 0x19c0, 0x1f00, 0x1c00, 0x0000, 0x0000}},
{'8', {0x0f3c, 0x19e6, 0x18c6, 0x19e6, 0x0f3c, 0x0000, 0x0000}},
{'9', {0x0f80, 0x18c6, 0x18cc, 0x1818, 0x0ff0, 0x0000, 0x0000}},
{'*', {0x018c, 0x0198, 0x0ff0, 0x0198, 0x018c, 0x0000, 0x0000}},
{'.', {0x001c, 0x001c, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000}},
{'?', {0x1800, 0x1800, 0x19ce, 0x1f00, 0x0000, 0x0000, 0x0000}},
{'!', {0x1f9c, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000}},
{'(', {0x01e0, 0x0738, 0x1c0e, 0x0000, 0x0000, 0x0000, 0x0000}},
{')', {0x1c0e, 0x0738, 0x01e0, 0x0000, 0x0000, 0x0000, 0x0000}},
{'#', {0x0330, 0x0ffc, 0x0330, 0x0ffc, 0x0330, 0x0000, 0x0000}},
{'$', {0x078c, 0x0ccc, 0x1ffe, 0x0ccc, 0x0c78, 0x0000, 0x0000}},
{'/', {0x001c, 0x0070, 0x01c0, 0x0700, 0x1c00, 0x0000, 0x0000}},
} ;
 
#define NGLYPHS         (sizeof(glyphtab)/sizeof(glyphtab[0]))
 
void
encodechar(int ch)
{
    int i, x, y, fch ;
    word fbits ;
 
    /* It looks sloppy to continue searching even after you've
     * found the letter you are looking for, but it makes the
     * timing more deterministic, which will make tuning the
     * exact timing a bit simpler.
     */
    for (i=0; i<NGLYPHS; i++) {
        fch = pgm_read_byte(&glyphtab[i].ch) ;
        if (fch == ch) {
            for (x=0; x<7; x++) {
                fbits = pgm_read_word(&(glyphtab[i].col[x])) ;
                for (y=0; y<14; y++) {
                    if (fbits & (1<<y))
                        digitalWrite(radioPin, HIGH) ;
                    else
                        digitalWrite(radioPin, LOW) ;
                         
                    delayMicroseconds(4045L) ;
                }
            }
        }
    }
}
 
void
encode(char *ch)
{
    while (*ch != '\0')
        encodechar(*ch++) ;
}
 
void
setup()
{
  Serial.begin(9600) ;
  pinMode(radioPin, OUTPUT) ;
}
 
 
void
loop()
{
while(timer < 300) //delay transmitt för 5 minutes
  {
  delay(1000);
  timer++; 
  }
timer = 0;

sensorvaluetemp = analogRead(A3);
sensorvaluevolt = analogRead(A2);
itoa(sensorvaluetemp,buf1,10);
itoa(sensorvaluevolt/11,buf2,10);

while(sensorvaluevolt <= 107) //Dont transmitt if voltage is below 10,5v
  {
  delay(10000);
  sensorvaluevolt = analogRead(A2); 
  }

encode("BEACON GRAY1 TEMP IS ") ;
if(sensorvaluetemp < 140)
  {
  displaytemp = (140 - sensorvaluetemp)*2;
  itoa(displaytemp, buf1,10);
  encode(buf1);
  encode("C ");
  }
else
  {
  displaytemp = (sensorvaluetemp -140)*2;
  itoa(displaytemp,buf1,10);
  encode("-");
  encode(buf1);
  encode("C ");
  }
       
encode("VOLTAGE IS ");
encode(buf2);
encode("V");
}

29
The RF Workbench / New 850mW HF beacon,
« on: February 05, 2022, 1748 UTC »
Hello everyone!

I just finnished a small transmitter, made from a design called El Pititico. Its a one transistor transmitter that also has a low pass filter and is surprisingly stable. It puts out 850mW after the low pass filter. It draws about 140mA in TX using 12v supply, im really happy with this design. The enclosure is printed in PLA, with a 3d printer. The 2n2222a transistor gets really hot, but it seams to be able to handle it.

When keying the TX with a BC547c i only get about 650mW on the TX, but using a 13,8v supply i guess it will get a bit higher. The Arduino Micro draws 42mA in stand by current, i will have to look at reducing that.



I found a nice program for the arduino so it can transmitt Hellschreiber:

Code: [Select]
int radioPin = 13 ;
int sensorvalue;
 
typedef struct glyph {
    char ch ;
    word col[7] ;
} Glyph ;
 
const Glyph glyphtab[] PROGMEM = {
{' ', {0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000}},
{'A', {0x07fc, 0x0e60, 0x0c60, 0x0e60, 0x07fc, 0x0000, 0x0000}},
{'B', {0x0c0c, 0x0ffc, 0x0ccc, 0x0ccc, 0x0738, 0x0000, 0x0000}},
{'C', {0x0ffc, 0x0c0c, 0x0c0c, 0x0c0c, 0x0c0c, 0x0000, 0x0000}},
{'D', {0x0c0c, 0x0ffc, 0x0c0c, 0x0c0c, 0x07f8, 0x0000, 0x0000}},
{'E', {0x0ffc, 0x0ccc, 0x0ccc, 0x0c0c, 0x0c0c, 0x0000, 0x0000}},
{'F', {0x0ffc, 0x0cc0, 0x0cc0, 0x0c00, 0x0c00, 0x0000, 0x0000}},
{'G', {0x0ffc, 0x0c0c, 0x0c0c, 0x0ccc, 0x0cfc, 0x0000, 0x0000}},
{'H', {0x0ffc, 0x00c0, 0x00c0, 0x00c0, 0x0ffc, 0x0000, 0x0000}},
{'I', {0x0ffc, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000}},
{'J', {0x003c, 0x000c, 0x000c, 0x000c, 0x0ffc, 0x0000, 0x0000}},
{'K', {0x0ffc, 0x00c0, 0x00e0, 0x0330, 0x0e1c, 0x0000, 0x0000}},
{'L', {0x0ffc, 0x000c, 0x000c, 0x000c, 0x000c, 0x0000, 0x0000}},
{'M', {0x0ffc, 0x0600, 0x0300, 0x0600, 0x0ffc, 0x0000, 0x0000}},
{'N', {0x0ffc, 0x0700, 0x01c0, 0x0070, 0x0ffc, 0x0000, 0x0000}},
{'O', {0x0ffc, 0x0c0c, 0x0c0c, 0x0c0c, 0x0ffc, 0x0000, 0x0000}},
{'P', {0x0c0c, 0x0ffc, 0x0ccc, 0x0cc0, 0x0780, 0x0000, 0x0000}},
{'Q', {0x0ffc, 0x0c0c, 0x0c3c, 0x0ffc, 0x000f, 0x0000, 0x0000}},
{'R', {0x0ffc, 0x0cc0, 0x0cc0, 0x0cf0, 0x079c, 0x0000, 0x0000}},
{'S', {0x078c, 0x0ccc, 0x0ccc, 0x0ccc, 0x0c78, 0x0000, 0x0000}},
{'T', {0x0c00, 0x0c00, 0x0ffc, 0x0c00, 0x0c00, 0x0000, 0x0000}},
{'U', {0x0ff8, 0x000c, 0x000c, 0x000c, 0x0ff8, 0x0000, 0x0000}},
{'V', {0x0ffc, 0x0038, 0x00e0, 0x0380, 0x0e00, 0x0000, 0x0000}},
{'W', {0x0ff8, 0x000c, 0x00f8, 0x000c, 0x0ff8, 0x0000, 0x0000}},
{'X', {0x0e1c, 0x0330, 0x01e0, 0x0330, 0x0e1c, 0x0000, 0x0000}},
{'Y', {0x0e00, 0x0380, 0x00fc, 0x0380, 0x0e00, 0x0000, 0x0000}},
{'Z', {0x0c1c, 0x0c7c, 0x0ccc, 0x0f8c, 0x0e0c, 0x0000, 0x0000}},
{'0', {0x07f8, 0x0c0c, 0x0c0c, 0x0c0c, 0x07f8, 0x0000, 0x0000}},
{'1', {0x0300, 0x0600, 0x0ffc, 0x0000, 0x0000, 0x0000, 0x0000}},
{'2', {0x061c, 0x0c3c, 0x0ccc, 0x078c, 0x000c, 0x0000, 0x0000}},
{'3', {0x0006, 0x1806, 0x198c, 0x1f98, 0x00f0, 0x0000, 0x0000}},
{'4', {0x1fe0, 0x0060, 0x0060, 0x0ffc, 0x0060, 0x0000, 0x0000}},
{'5', {0x000c, 0x000c, 0x1f8c, 0x1998, 0x18f0, 0x0000, 0x0000}},
{'6', {0x07fc, 0x0c66, 0x18c6, 0x00c6, 0x007c, 0x0000, 0x0000}},
{'7', {0x181c, 0x1870, 0x19c0, 0x1f00, 0x1c00, 0x0000, 0x0000}},
{'8', {0x0f3c, 0x19e6, 0x18c6, 0x19e6, 0x0f3c, 0x0000, 0x0000}},
{'9', {0x0f80, 0x18c6, 0x18cc, 0x1818, 0x0ff0, 0x0000, 0x0000}},
{'*', {0x018c, 0x0198, 0x0ff0, 0x0198, 0x018c, 0x0000, 0x0000}},
{'.', {0x001c, 0x001c, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000}},
{'?', {0x1800, 0x1800, 0x19ce, 0x1f00, 0x0000, 0x0000, 0x0000}},
{'!', {0x1f9c, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000}},
{'(', {0x01e0, 0x0738, 0x1c0e, 0x0000, 0x0000, 0x0000, 0x0000}},
{')', {0x1c0e, 0x0738, 0x01e0, 0x0000, 0x0000, 0x0000, 0x0000}},
{'#', {0x0330, 0x0ffc, 0x0330, 0x0ffc, 0x0330, 0x0000, 0x0000}},
{'$', {0x078c, 0x0ccc, 0x1ffe, 0x0ccc, 0x0c78, 0x0000, 0x0000}},
{'/', {0x001c, 0x0070, 0x01c0, 0x0700, 0x1c00, 0x0000, 0x0000}},
} ;
 
#define NGLYPHS         (sizeof(glyphtab)/sizeof(glyphtab[0]))
 
void
encodechar(int ch)
{
    int i, x, y, fch ;
    word fbits ;
 
    /* It looks sloppy to continue searching even after you've
     * found the letter you are looking for, but it makes the
     * timing more deterministic, which will make tuning the
     * exact timing a bit simpler.
     */
    for (i=0; i<NGLYPHS; i++) {
        fch = pgm_read_byte(&glyphtab[i].ch) ;
        if (fch == ch) {
            for (x=0; x<7; x++) {
                fbits = pgm_read_word(&(glyphtab[i].col[x])) ;
                for (y=0; y<14; y++) {
                    if (fbits & (1<<y))
                        digitalWrite(radioPin, HIGH) ;
                    else
                        digitalWrite(radioPin, LOW) ;
                         
                    delayMicroseconds(4045L) ;
                }
            }
        }
    }
}
 
void
encode(char *ch)
{
    while (*ch != '\0')
        encodechar(*ch++) ;
}
 
void
setup()
{
  Serial.begin(9600) ;
  pinMode(radioPin, OUTPUT) ;
}
 
 
void
loop()
{

    sensorvalue = analogRead(A0);
   
    encode("CQ TEST CQ TEST ") ;

}
The TX is designed by PY2OHH and refined by DX explorer on youtube. The Arduino code is from the link below, at Brainwagon.org

https://brainwagon.org/2012/01/11/hellduino-sending-hellschreiber-from-an-arduino/

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HFUnderground T-Shirt
HFUnderground Garden Flag
by MitchellTimeDesigns