Bits and pieces of things that I'm currently working on, or that I've worked on in the past.
The SimpleX Super Mark II
January 2012
I was poking around looking for a first project to introduce myself to tube radio design. I found this project documented in the 1963 edition of the ARRL Radio Amateur's Handbook. I understand that it was originally designed by Byron H. Goodman, W1DX (SK). It's a neat design.
- Description (4.4 MB PDF)
- Annotated Schematic (415 KB PNG)
- Close-up of the top of the chassis (640 KB JPG)
- Close-up of the bottom of the chassis (640 KB JPG)
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My proposed modification to the power supply (45 KB PNG)
The original supply design used a 125V secondary and a voltage doubler, but the transformer I had has a 250V center tapped secondary. Selenium rectifiers are undesirable for a number of reasons, so I'm using a silicon rectifier with 1N4007 diodes instead. For safety I added a fuse, and a 500K bleeder resistor in parallel to the filter.
PDP-11/35 Restoration
May 2012
I've always loved classic computers, and I'm a particular fan of computers made by Digital Equipment Corporation, so I was absolutely thrilled to recently get my hands on a vintage 1973 DEC PDP-11/35.