Homebrew Processor with Discrete Transistors and LEDs

I've been working with an Arduino today.  Seeing this video makes me feel like such an APPLIANCE OPERATOR.  FB OM!  No store-bought mystery boxes for him! 

Thanks to Steve N8NM for alerting us to the magnificent project.

More details here:

http://www.popsci.com/man-builds-huge-megaprocessor

Analog TO THE MAX! An Old School Readout for the BITX 40

Perhaps this was a reaction to a frustrating morning spent trying to get a 20x4 digital display to work with an Si5351 and an Arduino Uno via an I2C bus (I feel my blood pressure rising just due to the typing of those words).   After much digital fiddling, I declared a "BASTA!"  and looked around the shack for an antidote for the digital frustration.  There on the bench was my fully analog BITX40Module rig, with its homebrew L-C analog VFO.   It needed a better frequency readout. And this morning, it got one.  

The pointer is Sharpie ink on a bit of PC board.  It is held in place by superglue, suspended by a piece of wood about 1/4 inch off the chassis (to reduce dial parallax).  The numerals are in Dymo tape -- there was not enough room for the "7" but I think I will be able to remember this. 

Very therapeutic and satisfying.   

25 Watts From a Single IRF510

I should have tried this a long time ago.  It works great.  The power supply that I picked up at the Kempton Park rally many years ago  happens to have a 25 volt unregulated output.  Coincidence you say?  I think not.  TRGHS.  

 Farhan provides a really excellent description of how to do this:

http://hfsignals.blogspot.com/p/25-watt-linear-for-40-and-20.html

"Sideband Suzy" and the History of SSB

Farhan alerted us to a very interesting presentation on the history of single sideband:  It was in episode 81 of Bob Heil's "Ham Nation" show.  It starts at minute 22:

https://www.youtube.com/watch?v=xSF0WBdK1IQ&feature=youtu.be

Two things really caught my attention:

-- Note how OM Carson, way back in 1915, had figured out how to get rid of the carrier, but needed some way of eliminating the unnecessary sideband.  He did it by using his antenna tuner as a filter.  FB OM!

-- In the early days of SSB, when it was an exciting new technology, hams had regular "sideband dinners."  At these events an award was presented.  Kind of like an Oscar or an Emmy I guess.   The award was the "Sideband Suzy" (see above).    Kind of a classic figure...  but half of Suzy was missing!

Putting a Heatsink on the BITX40 Module

The fan that I installed yesterday was driving me nuts.  It was noisy, both acoustically and electrically.  And I would occasionally get my fingers in the blades.  Not good.  While it did seem to keep the IRF510 from getting too hot, I knew that a real heatsink would do better thermally.

But how was I going to attach the sink to the transistor?  That tab on the IRF510 goes to the collector, so if it touches a grounded heat sink, you get a short.   A nylon screw and some mylar between the transistor tab and the heat sink is one option.  But I didn't have a nylon screw.  So I decided to just keep the heat sink electrically insulated from the chassis.

This project required me to refresh my memory on how to tap a 4-40 hole.  I went back and watched the short video I made on the tribal knowledge that Pete had shared with me.  Out came the Tap and Die gear and the machine oil.  The process went very smoothly.

Here is what I did to get the heatsink in place:

1) After removing the original heatsink, I gently bent the leads on the IRF510 so that the transistors outer edge would be flush with the edge of the PC board.
2) I put a strip of thick tape (Gorilla Tape) along the lower side of the heat sink. This will keep the heat sink from shorting to the chassis.
3) I placed the heatsink where I wanted it, and carefully marked where the mounting screw (through the transistor's tab) should go.
4) Drill!  Tap!  (see video)  https://www.youtube.com/watch?v=LuqliWT1k5A
5) I applied some heat sink compound (or Desitin!) and then attached the transistor to the heatsink.
6) I put a few drops of glue between the heatsink and the board and the chassis, just to mechanically stabilize it a bit.
7) Bob's your uncle.

It seems to work great.  The MOSFET stays cool. even after long "old buzzard" transmissions.  And I notice no stability problems.  It was fun  to put to use some tribal knowledge and refresh a mechanical skill.