Topics

1

The RF Workbench / Ten Minute Transmitter

« on: February 26, 2016, 0423 UTC »

It's been a while since I've had time to do some radio tinkering.  I came across an interesting schematic last weekend for a very simple transmitter called the Ten Minute Transmitter.  I wrote about it here: http://makerf.com/posts/ten-minute-transmitter

If you buy a store bought RFC and use some capacitors in parallel instead of a variable capacitor, the only 'hard to get' part is the crystal.

I've done some tinkering with it since the initial build and have been able to amplify the signal up to about 9 watts!  I'm going to play with it some more and post about it again soon.

2

The RF Workbench / 5 watt crystal oscillator transmitter

« on: July 28, 2014, 0401 UTC »

I was playing around with amplifying a basic crystal oscillator transmitter.  I was able to get it up to 5 watts with an IRF510.  As I mention in my write up, this isn't a design you want to put on the air.  IMHO it's far too dangerous to be amplifying square waves to 5 watts -- the RF pollution will be all over the place.  But, it's a fun little circuit to experiment with into a dummy load, and burn your fingers (the IRF510 gets HOT!).

More Fun With Crystal Oscillators: Amplifying RF:
http://makerf.com/posts/more-fun-with-crystal-oscillators-amplifying-rf

3

The RF Workbench / Experimenting with Colpitts Oscillators

« on: April 05, 2014, 0346 UTC »

Just posted a write up on my site that some may be interested in:

Experimenting with Colpitts Oscillators
http://makerf.com/posts/experimenting_with_colpitts_oscillators

For those of you who don't know, the Colpitts oscillator is a common RF oscillator circuit.  Useful for when you don't have a crystal in the frequency range you want to use.  The colpitts can be scaled for pretty much any frequency range based on the L and C values in the tank circuit.

4

The RF Workbench / Jameco asking hams which parts they should stock

« on: March 11, 2014, 2055 UTC »

Got an email from Jameco today, and it appears they are soliciting radio enthusiasts about what parts they should stock.  Might be a great opportunity if they start stocking some hard to find components.

Here's the link, which has another link at the end where you can send feedback:
http://www.jameco.com/Jameco/email/ham-world.html

5

The RF Workbench / Measuring transmitters with an oscilloscope

« on: September 10, 2013, 0137 UTC »

All,

I just posted a write up about measuring transmitters with an oscilloscope.  A good one for beginners out there that want to get down some basics.

Essential Equipment: Measuring RF Circuits with an Oscilloscope
http://makerf.com/posts/essential_equipment_measuring_rf_circuits_with_an_oscilloscope

As always, comments and feedback are welcomed!

6

The RF Workbench / A simple shortwave pirate transmitter build

« on: August 27, 2013, 2130 UTC »

Hello all,

I recently joined the forums after being a long time lurker (probably a few years now), and am mainly interested in the electronics / homebrew aspect of radio, but do a fair amount of SWL and general ham activities as well.  My favorite past time is building simple transmitters and want to share some of my builds to get feedback and encourage others to pick up a soldering iron and have some fun.

I recently posted on my website an article that would be of particular interest to the community here.

So You Want to Be a Shortwave Pirate
http://makerf.com/posts/so_you_want_to_be_a_shortwave_pirate

Essentially this takes the Michigan Mighty Mite transmitter build and adds on an audio modulator and low pass filter to create a very basic shortwave pirate transmitter that puts out about 1/2 watt.  Of course, this should only be used while hooked up to a dummy load!

The circuit is simple enough for novices to build, and is pretty fun to experiment with.  Feedback and discussion are welcome!