Month: October 2014

Pete’s Homebrew Double Balanced Mixer Video (Part 1)

Another great video from the famed Italian Director Giovanni Manzoni! Bravo Giovanni!

Pete’s discussion of double balanced mixers and the associated toroids has made me feel uneasy about my efforts in this area. I wonder if my diodes were completely matched. And I KNOW that my toroids are not as well done as Pete’s.

I recently put an SBL-1 into my old, long-evolving 20 meter ceramic resonator DSB rig. Careful with those nice little boxes! A bit too much juice and you can fry the little internal toroids (as I have done!).

A while back I found in an RSGB Handbook a nice diagram showing how the diode ring mixer does its thing:


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SolderSmoke Podcast 166: Getting Started in Homebrew Radio

SolderSmoke Podcast 166 is available for download:

http://soldersmoke.com/soldersmoke166.mp3

Bench Report: Pete working on Direct Conversion Receivers.
Bill on his 2B and on 20DSB rig, and an M0XPD/Kanga DDS kit, and a 140 watt amp.

GETTING STARTED IN HOMEBREW:
Start simple: Build an oscillator. Make it oscillate!
Gather tools, simple test gear, and books.
Try to understand what you build.
Build a direct conversion receiver.
Don’t fear the toroids!
Be patient. This is not Plug and Play.
Build a DSB transceiver.
Little tips:
Protect variable caps.
Use heat sinks.
Use reverse polarity protection.
Don’t breathe the solder smoke! Ventilate your bench.

 China Radio International Mystery Solved.
Book Recommendation: “International QRP Collection” by Dobbs and Telenius-Lowe
MAILBAG

Our book: “SolderSmoke — Global Adventures in Wireless Electronics” http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Sines, Squares, Harmonics, ‘Scopes, FFTs, and Sounds

Bil Herd of Hackaday did a very nice video on Sine Waves, Square Waves and FFTs. This is, of course, an important part of understanding how mixers mix. I look forward to his upcoming video on Direct Digital Synthesis.

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Hunting for Sprites

Don’t let the comments about “positive lightning” and “gravity wave” cameras turn you off — in the world of meteorology, these terms seem to make sense (but I had to do some Googling). The New York Times article on this topic is very interesting:

http://www.nytimes.com/2014/09/30/science/on-the-hunt-for-a-sprite-on-a-midsummers-night.html?_r=0

Our book: “SolderSmoke — Global Adventures in Wireless Electronics” http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20