Saturday, October 28, 2017

Raduino as NBFM TX


Here is a neat, 30 minute hack for your Raduino to turn the Si5351 into a pretty stable, solid NBFM transmitter. The hack is to add a varactor diode in series with the reference crystal oscillator and drive it with audio. I used a very simple audio amplifier to boost up the audio. Here is the circuit:

Attach a small piece of wire to clock 2 to radiate the signal. Here is the sketch :

/**
 * This source file is under General Public License version 3.
 */
#include <Wire.h>
#include <si5351.h>
Si5351 si5351;

void setup()
{
  int32_t cal=0;
  
  si5351.init(SI5351_CRYSTAL_LOAD_8PF,25000000l, cal);
  si5351.set_correction(cal);  
  si5351.set_pll(SI5351_PLL_FIXED, SI5351_PLLA);
  si5351.set_pll(SI5351_PLL_FIXED, SI5351_PLLB);

  //si5351.drive_strength(SI5351_CLK2, SI5351_DRIVE_2MA);
  si5351.output_enable(SI5351_CLK0, 0);
  si5351.output_enable(SI5351_CLK1, 0);
  si5351.output_enable(SI5351_CLK2, 1);

  si5351.set_freq(14500000000l,  SI5351_CLK2);   
  
  delay(10);
}

void loop(){

}

Thursday, August 31, 2017

Ergonomic BITX Enclosure -- 3D Print


Wow, Michael's amazingly cool BITX enclosure looks like you could use it to ask Scottie to beam you up. 
Put an end to those freakish contortions -- 3D print yourself an Ergonomic BITX box! Very FB Michael. Thanks. 

Hi Bill and Pete:

I thought you’d be interested to see my ergonomic enclosure for the BITX40. While operating homebrewed regen radios, I noticed that my hands/arms/shoulders were becoming uncomfortable after a while. After thinking about this for a few days, I realized that the dials on the front of these small radios were forcing my hands into freakish contortions—and having both hands on the dials at all times while tuning made matters worster faster! So I did some homework and determined that our arms and hands most naturally hold things toward each other, as though they are holding a small cylinder by the ends. But the conventional “dials-and-speaker-facing-front” radio case forces us to twist our hands up and outwards from our bodies to twist things. See my blog post http://blog.generaleccentric.net/?p=2009 for illustrations of this problem.

My enclosure design for the BITX40 re-orients the volume and tuning knobs toward the sides of the radio, making their operation much more natural—and pleasant. Although it’s not retro, it does have an unconventional appearance and should fit in quite naturally with all the other homebrewed solutions featured on SolderSmoke. 

You can visit my post at http://blog.generaleccentric.net/?p=2082; the box is available for download and printing at Thingiverse: https://www.thingiverse.com/thing:2508147

By the way, I also have a 3D printable mic for the BITX40: https://www.thingiverse.com/thing:2500483

73, Michael VE1LEB

Saturday, August 26, 2017

Speech Processor and Antenna Tuner/SWR meter for BITX



Check out the blog of homebrew wizard K.P.S. Kang.   OM has a nice speech processor based on the LM386.   He also has a very simple antenna tuner and SWR bridge.  FB OM.  

http://smallwonderqrp.blogspot.com/2017/08/two-essential-add-ons-for-bitx-and.html

Monday, July 24, 2017

KC8WBK's Cakepan BITX Enclosure and PVC Mic/PTT Grip


I talked to Paul KC8WBK last night during the regular 7277 kHz Sunday night BITX gathering (7 pm local). I like his BITX enclosure.  Very practical and economical.  It provides ready access to the circuitry.  He also has nice enclosure for the microphone and push-to-talk switch. He has more info on his QRZ.com page. 


Thursday, June 1, 2017

KY3R's Metalized Cigar Box BITX Enclosure


Bob KY3R writes:

Bill:  I was watching your visit with Farhan, and you mentioned your penchant for building projects into wooden hobby boxes, and using copper  flashing for shielding. I want to share my solution. 

I snatched up any old cigar boxes I come across. For shielding I use "metal repair tape." This is the stuff used for joining or repairing dryer lint vent ducts, and it is available at any hardware store. Very lightweight, and you just cut the desired lengths, peel off the backing, and press onto the inside of the box. The only drawback is that it is aluminum and doesn't take solder very well, but it is easy enough to add one or two short lengths of wire from the circuit ground plane to a terminal bolted down onto the case interior. 

The attached photos show my current project--a Por Larranaga cigar box in the process of being converted into a home for a BitX-40! I haven't yet fully decided exactly how to position the unit in the box, but as shown in one of the potos, it fits with plenty of room for later mods. As for other decisions, I toyed with the idea of painting or covering the outer box, but I am leasing toward leaving the original cigar box labeling. Arguable adds a bit of "soul," plus who needs a clean panel and all that fancy stenciled lettering anyway.I'll know which knob is which! <g>

73, and as always, thanks to you (and Pete, of course) for your continued work on the SolderSmoke  podcast.

Bob Keller, KY3R




Thursday, April 6, 2017

Hot Water BITX 40 Hack

Fred's idea really resonated with me.   My first SSB rig was an HW-32A, the 20 meter version of the rig shown above.  If -- as I suspect -- these rigs are anything like the HW-101, they are not aging well. Heath's drive for economy resulted in rigs that don't hold up to well over time. I remember the sound of the  plastic HW-101 dial clutch cracking when I pushed the button.

BITX40 Modules to the rescue! Put a mono-band board inside an old mono-band rig.   There are a lot of possibility here.  Some ideas:

-- Put that Heath VFO to use.  Maybe convert it to solid state.  Or just put the LCD from an Si5351 in the window (Pete did this with an HW-101).

-- Get the S-Meter wiggling.  

-- Keep the final amplifier circuitry in there and let the BITX drive it.  This will give you a QRO option.  Bill N2CQR 

Hello Fellows,
Attached is a picture of my BITX-40 V3 adapted to a Heath kit Single Bander HW22. This is a work in progress but what a neat way to bring an old boat anchor into the present.
 
The only parts of the HW 22 used were the front panel and case and knobs. Modifications yet to be  incorporated include: AGC , a USB port on the front panel to access the Arduino, and a PTT/CW mode switch.
 
I enjoy your pod cast and web site…Best of 73 KC5RT.

Wednesday, March 29, 2017

ND6T's Forward and Reverse Power Meter for the BITX


RF Monitor
by Don Cantrell, ND6T

In response to several requests for a VSWR and output power monitor I have developed a simple circuit to be easily added to the BITX (or any transceiver) and some software to get it working. I used a 20 dB directional coupler design, sometimes called a “Stockton bridge”, that is simple, broadband, and requires no adjustment.

The sensor circuitry is mounted on a small piece of printed circuit board that is held in place under the mounting nut of the BNC antenna connector, replacing the ground lug that was originally supplied. The (brown) wire from the 2-conductor “ANT1” plug feeds through the center of one toroid core (T1) and solders to the BNC jack, the other (black) solders to the new board's ground plane. Two new wires connect to the Raduino plug for reading and display of the results.

I began with a square of un-etched printed circuit board stock, one inch on each side, and drilled a 3/8” hole near one corner to fit over the antenna jack. Leaving enough room for the mounting nut, I glued 4 small pieces of PC board as solder pads. The two transformers are T37-43 ferrite cores wrapped with 10 turns of AWG#24 wire in a single layer. The 50 ohm terminations are ½ watt 51 ohm resistors. I hand-selected two of the ones closest to 50 ohms but this is not critical (what's an ohm between friends?) ¼ watt will work fine at these levels. I used two 1N34A diodes for detectors.

I mounted all of the components upright to save space. A short jumper wire feeds from T1 secondary through the center of T2 to the forward detector as that primary winding. Note that you do not wrap this around the core, just pass it through like the antenna lead on T1.

Don't have any #24 wire? Use whatever you have that will fit 10 turns. Don't have a T37 core? A T50 or even T60 will work. It is best, however, to stick to 43 mix ferrite unless you adjust the turns accordingly. Capacitor voltage or temperature coefficient is not important. Got lots of room around the antenna connection on your build? Then go large with the PC board and give yourself some space for component mounting and ease of connection.

Testing is simple. If windings have the proper polarity then, when you transmit into a dummy load, there should be a couple of volts DC on the “Forward” solder point and a very low voltage on the “Reflected” pad. The coupler works the same in both directions, meaning that if it were built outside of the BITX, then you could reverse it and get the same readings by switching voltage pads. A nice check of operations. 7 watts on my build resulted in a bit over 2 volts volts on the output, well under the maximum 5 volts allowed on an Arduino® A/D input.

I included some formulas in the software to average the peaks during SSB operation and displaying it every 3 seconds. The results are also displayed after a half-second key down in straight-key mode. The power reads out as watts in both forward and reverse directions. As usual, the Arduino sketches are available free by emailing ND6T@arrl.net.

Not using a digital readout? Just attach meters and adjustment pots to the output connections. If you want just one single-movement meter then use a switch and a trim pot for each switch position.

de ND6T