WB0SMX

  MKARS80 80 Meter SSB Transceiver – Part 3 Filed in Kits on Feb.18, 2012 Construction of the MKARS80 Transceiver continues with the installation of the bag #4 components. This bag contained all of the active devices, as well as the crystals for the BFO and filter. As these were just dropped into the holes, I didn’t take a lot of pictures during this phase. Here is the board after all of bag #4 has been populated:   Bag #5 contained the PIC chip, LCD display, controls and variable capacitor. I could not get the polyvaricon leads to fit into the holes on the board, and ended up trimming them thinner. At first I tried my side cutters, but they are getting a little dull. In the end, I used some toenail clippers! After trimming, the leads fit through the holes OK.    Here is the component side with all of the bag #5 components installed (except the display and PIC chip).  And here is the back of the board, with the controls poking through…    ...

  MKARS80 80 Meter SSB Transceiver – Part 2 Filed in Kits on Feb.18, 2012 Construction of the MKARS80 Transceiver continues with the population of bag #3. This bag contained most of the toroids and bobbins to wind. One of the challenges, from the colonies side of the Atlantic, is the lack of an intuitive feel for the metric system. I was thinking that 50mm = 0.5 cm. But it turns out that it is 5 cm. I guess if I would have thought about it, I could have compared it to electronics. 1 milliamp = 0.001 amp. So 1 millimeter = 0.001 meter, whereas 1 centimeter = 0.01 meter. So now I get it. Anyway, even with trimming the leads 10 times too short on the first transformer, it was still long enough to reach. Note that it takes a really hot soldering iron to burn the insulation off of the enameled wire. I used about 780F degrees when soldering in the transformers. For the rest of the components, I used about 750F degrees.   Transformer T4, with leads cut way short. After...

  MKARS80 80 Meter SSB Transceiver – Part 1 Filed in Kits on Feb.07, 2012 The next project up on the bench is a unique kit from England, the MKARS80 80 meter Single Sideband Transceiver. It was designed and originally kitted by the Milton-Keyens Amarteur Radio Society , and is designed to be something inexpensive but useful for folks to get into building their own rigs. Now kitted by radio-kits , it is probably the most bang for the buck I have seen in a kit in the past couple of decades. This project is an offshoot of the Bitx-20 transceiver, and follows the same basic scheme. The unique part is that it incorporates a frequency stabilizing scheme called a huff-and-puff circuit . This circuit works by sampling the frequency, and when a slow drift is detected, it feeds a small offset voltage to a voltage variable capacitor to bring the frequency back into range. In addition, the rig has an LCD display to show operating frequency, battery voltage and huff/puff status. This...