Les projets de VE2CUY

Project 4 – SW tube receiver

Document converti depuis ve2cuy.com/blog — dernière modification : 2010-05-23

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Update – 22.05.2010

I did a little work on the project:

Replaced 10.7 “IF” cans by 455kc ones.

Selected all 12 volt filament tubes: 12BE6 (converter), 12BA6 (IF), 12AV6 (DET, AVC, AF-PRE) and 12BA6 (AF-AMP).

Fixed B+ at 20 volt (-12 + 12 from an ATX-Power supply). Current is around 4ma (yep!).

Heaters current = 650ma.

I am starting to get results from it!

.

▶️ Vidéo YouTube : Voir la vidéo

Schematic – version 1

Next steps:

– add rf amp stage
– add a third “IF” stage (done)
– add a magic eye tube on the AVC signal (done – but wont make it to the final version)
– add a regeneration stage on V2 (not shure any more …)

Update – 28.05.2010

With the initial concept, I was thinking of a 50C5 35W4 12BE6 12AU6 12AV6 alignment with 10.7 IF.

Finally, I decided that it was too usual and I did not want it to be 117volts live.

So, the actual state of the project is:

Tubes: 12BE6 (converter), 12BA6 (IF1), 12BA6 (IF2), 12AV6 (DET) and 12BY7 (AF-AMP – It as a better sound than a 12BA6),

2 x IF stages,

3 x 455kc transformers used in transistor radios,

Controlled auto-Oscillation of the first IF-AMP (BFO) for SSB and CW reception,

Interchangeable L1, L2 and L3 for multiband,

Very low (24volts – from an ATX power supply: +12 + -12) B+. I did some tests with 12volts and it works very well with headphones.

I will add a frequency counter on the converter tube (LO – IF) to display the reception frequency using a 74HC161 and an Arduino board to drive Nixie tubes or a LCD display.

Looking at the following picture, I understand why I love those tube radio projects; they are so great in the dark…

Nixie or LCD ? …

Schematic – version 2

Update 20.06.2010

I’ve made some progress on my 5 tubes shortwave radio.

The frequency counter prototype is working.

I’m using a MPF102 as an RF amp, then the signal is feed in a 74HC161 (16x prescaler) and finally into an atmega328p for counting.

See the frequency counter at work:

▶️ Vidéo YouTube : Voir la vidéo

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Source code:
=====================

/*
Project: Frequency counter for the 5 tubes (3 IF) homemade shortwave receiver
By: VE2CUY – Alain Boudreault
Date: June 2010
*/

#include #include #include #include

//#define __debug

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 3, 2, 1, 0);

// Read fz input via Atmega328 pin 11 (arduino digital 5)
void setup() {
lcd.begin(16, 2);
lcd.print(« L.O. frequency »);

#ifdef __debug
Serial.begin(57600); // connect to the serial port
Serial.println(« Test fz counter »);
#endif
lcd.clear();
delay(500);
}

long int frq;

void aff_number(long int number){
long int divider = 100000;
long int reminder;
int digit;

for (int i=0;i<6;i++){  
  reminder = number % divider;  
  digit = (number – reminder) / divider;  
   
  #ifdef __debug  
    Serial.print(digit);  
  #endif  
  lcd.print(digit, DEC);  
  if ( i == 1 || i == 4) {    // format -> 00.000.0  
    #ifdef __debug  
      Serial.print(« . »);  
    #endif  
    lcd.print(« . »);  
  }  
   
  number=reminder;  
  divider/=10;  
} // for i  
 
#ifdef __debug  
  Serial.println( » MHz »);  
#endif  
lcd.print( » MHz « );  

} // void aff_number
void loop() {
FreqCounter::f_comp=1;
FreqCounter::start(10);

while (FreqCounter::f_ready == 0){  
  frq=FreqCounter::f_freq;  
}  
  
lcd.setCursor(0, 0);  
lcd.print(« LO: »);  
frq\*=16;                  // Adjust for prescaler  
frq+=90;                //frequency fine tuning  
aff_number(frq);  
lcd.setCursor(0, 1);  
lcd.print(« FZ: »);  
aff_number(frq-4550);  //IF = 455KC    }