12/18/2014

First Steps



So...the question I asked my self was "what the heck shall I build?" Now that the "knack" has struck, where do I go from here? 

So many articles and instructions out there have a phrase much like "...and pull <component> from your junk box..." or presume that the reader has ready access to tons of advanced test and measurement systems. That certainly does not describe me. 

Allow me show you the parts available in my junk box:


My test equipment list is only slightly more comprehensive; I do have a DVM, although it won't do current measurements. I must have been exceptionally cheap the day I bought that one...

Filling the junk box can be handled with the judicious application of magic plastic cards, with some guidance from Pete Juliano (N6QW) in his bit on what should be in an experimenter's junk box. On the same page that has the junk box discussion, there are some great pieces on construction techniques and homebrew test gear, so perhaps I'll "self-help" my way in to some functional test gear.

As I mentioned in my previous post, I don't have even my Technician Class amateur radio license so I won't be building any transmitters yet (if I can't use it I can't see the point in building it). Well, if one cannot or will not build a transmitter and one is interested in radio, that only leaves us with the...receiver

I won't bore anyone with the lengthy list of design ideas a sources I pored over to finally find a design to build up, but ultimately the Neophyte (PDF link) 40 meter receiver from John Dillon was the winner. Some thought was given to an all-discrete-component project, but baby steps are needed for someone who has wielded more PowerPoint slides than soldering irons in the last two decades.

The Neophyte design is a simple one, both in concept and physical design:

Neophyte 40M Direct Conversion Receiver

  • Direct Conversion design - no IF needed.
  • Tuned front-end for some pre-selection.
  • Double balanced Gilbert Cell mixer in the form of an SA602 chip.
  • Wide tuning range oscillator circuit.
  • Simple low pass filter.
  • Ubiquitous LM386 style audio output amplifier.
Give what little I have of parts on hand or test equipment, simpler is better, no? Well, we'll have to see...



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