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Ten Minute Transmitter

Last weekend I was browsing the internet for radio circuits and came across an interesting design I've never seen before, nicknamed the Ten Minute Transmitter.  The design apparently originated in 1996 in an amateur radio club QRP publication.  The name originates since the original author claimed he built this transmitter and make a QSO with it in just 10 minutes time.  Impressive!

I didn't set a stopwatch to time myself, but I can tell you that I was able to slap this rig together on a breadboard and tune it up very quickly.  There are no coils to wind (unless you want to); it tunes a wide range of crystal frequencies, and it outputs an easy 500mW AM signal.  I had three crystals on hand, and was able to load up frequencies 6925 kHz, 14322 kHz and 28266 kHz without problem.

Here's the schematic:

ten minute transmitter schematic

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Posted: Feb 25, 2016

Keyword tags: shortwavetransmitterqrpschematicAM transmitterelectronics500mW

ARRL Field Day 2015

It's already been a month since the 2015 ARRL Field Day, so I better get this post up soon or else it will be old news!  The the last few years I've tried to get on the air for some portion of Field Day.  You can read about my 2013 and 2014 experiences on this site.  Each year I try to do things a little different, and this year was no exception.

ARRL Field Day 2015

For those not in the know, Field Day is an annual amateur radio event sponsored by the ARRL to encourage operators to get on the air, and make contact with as many other radio operators as possible.  People participate for many different reasons.  Some treat it like a contest, trying to bag the highest score possible.  Others, use it to test portable or emergency operations.  And, probably most people who participate just do it for casual fun.  I'm usually in that last boat even though I have in the past operated on emergency power, for fun.

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Posted: Jul 29, 2015

Keyword tags: arrlfield daycwradio operating

Dayton Hamvention 2015 Roundup

This past weekend was the 2015 Dayton Hamvention, the biggest convention dedicated to amateur radio.  I had the pleasure of attending for the first time last year and was happy to return this year.

My goals were: to pick up some components for new projects, enhance my station with some new equipment, shake hands with some of the folks I met last year, and enjoy a day trip with my father.

dayton hamvention 2015 tickets

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Posted: May 20, 2015

Keyword tags: dayton hamventionham radio

A Crystal Powered Steampunk Matchbox Radio

One of my friends recently had a birthday, and I got the idea to make him a simple steampunk themed matchbox radio.  I'm not a steampunk expert, but I do know that devices should work without electricity.  So, what better than a crystal radio?

Crystal radios in their most basic form require no electrical power, and are directly powered by the radio waves floating around us.  Of course, you can add a little amplification to boost performance, like in my Altoids tin crystal radio, but it's not required.

steampunk crystal radio

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Posted: Feb 25, 2015

Keyword tags: crystal radiosteampunkschematicelectronicsbasicsmatchbox radio1N34 diode

Make Your Own Rocket Radio with the TA7642

When my mom was a kid she owned a rocket radio, which was type of TRF crystal radio that was a popular kids toy in the 50's and 60's.  As a kid one of my favorite past times was tuning the AM dial on my favorite radio (after bedtime); it turns out she did the same as a kid with her rocket radio, pulling in stations around the north east US corridor.

vintage rocket radio

You can find vintage rocket radio's on eBay, but as a Christmas present I decided to make an updated model for her using the TA7642 IC.

The TA7642 is a complete AM radio receiver on a chip.  With a few extra components, you can have a fully functional TRF radio receiver in the palm of your hands.  In fact, there's a whole community of people that build use these types of IC's to build matchbox radios!

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Posted: Jan 25, 2015

Keyword tags: rocket radiota7642mk484zn414AM radioschematicmake a radio