Monday, 1 January 2018

Building a BITX40 40M SSB Radio

This is the first in a series of posts about the BITX40 radio, the next post is here.

The radio kits from HF Signals are quite popular because they are:
  1. inexpensive;
  2. hackable in both hardware and software;
  3. well supported;
  4. work well considering they are inexpensive and hackable.
The kit doesn't come complete, which makes it easier and less expensive to ship. But that does mean you will need to come up with a power supply, a case (or at least some way to mount the boards and controls), complete or find a microphone assembly and some others things. Some may see this as a drawback, but I see it as an advantage if your goal is to experiment with the radio rather than simply use it as you would any other appliance. You have the option of only building that which you need for you experiments.

My radio kit arrived in September but I did not really have time to put the radio together, and had not decided on a case. I finally settled on a case from Amateur Radio Kits World-Wide, the colour is very nostalgic of my days as a signalman.

Universal Case Siemens Grey II & Accessories

It comes with some useful parts not included with the BITX40
The case, like the BITX40 ships from India, but the only shipping options is by Post. Never the less it arrived at my mailbox in Canada less than three weeks after I ordered it right in the middle of the holidays. Perfect timing to put it together.

The first thing I did was test fit the boards and parts into the case. Doing this while reading the wire up instructions gives you a better idea of how the wires traverse the case and a chance to consider various options. I learned three things while doing this.

First, the BIT40 diagram is a bit confusing because it shows the Raduino board from the side facing the front of the case, rather than the side you would be looking at while running the wires. The text instructions are better, but again from a point of view I would not have chosen. But this is not a huge problem.

Second, I had to ream out some of the mounting hols to get them large enough to mount the parts. Again not a huge problem, nor unexpected since the case is powder coated, but one you should be prepared to deal with.

Third, the voltage regulator on the Raduino protrudes past the left side of this style of case. Again easily dealt with by carefully folding the regulator the other way.
Voltage regulator folded back between the Raduino and the LCD display.
The rest of the installation was quite easy as described on the BITX40 web pages.
Left side of the radio.

Right side of the radio.
If you look closely you will notice that I have not completed the hook up. I have not:
  • provided for MIC or headphone jacks,
  • installed a PTT switch or any way to get the radio to transmit,
  • trimmed the shaft of the tuning pot.
This is because I intend to do a number of modifications. The first step in this process will be to decide on which firmware to run. But these are discussions for a later post. I will leave you with pictures of the front and back panels and an anecdote of my first test.
Front panel.

Back panel.
The only antenna I have at home is a 2m ground plane whip in my attic which works well for me on 70cm as well. Once the radio was completed and knowing there was no way I could accidentally transmit and perhaps damage the rig I hooked up this antenna and started tuning around the band. I quickly game across a stations calling "CQ contest" likely for this RAC event. I was able to make out some VA3 call signs. Some more tuning and I came across a station from Long Island NY calling "CQ DX" and listened to him for a while. Not a bad days work as a HAM if I do say so myself.


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