Amateur Satellites

By Mike November 24th, 2009, under Uncategorized

I’ve always had an interest in making contacts over amateur satellites. Not only did the idea of talking to someone over a satellite seem really cool, but it can be done with basic equipment that almost every ham has. So, this week I decided to make an honest attempt at making a satellite contact–and it worked!

For receive, I used a handheld 440 MHz cubical quad antenna that was built for foxhunting, not satellite work. That said, it makes a pretty awesome satellite antenna due to its light weight and compact size. To transmit, I simply used the whip mounted on the top of my Jeep. The antenna probably provides somewhere around 3-5 dB of gain, but not necessarily directed upwards. I set my mobile to output 10W.

My first contact was on Friday, November 20th and I made it from the Chicken Hill parking lot on the campus of Virginia Tech (Grid Square EM19), on satellite SO-50. Sadly, I didn’t buffer the call of the other station, so I was unable to log it correctly. My second and third contacts occurred on Monday night, November 23rd, and were also on SO-50. The first contact was ZL7VX, who I believe was stateside in FM18. I then spoke with N9AMW in EN52 in Wisconsin.

Working the bird at night was definitely a pleasurable experience as I didn’t feel rushed to make the contact and get off the bird; there was plenty of time to slowly exchange calls and say a few words as well.

I’m looking forward to continuing to work satellites in the near future, and look for updates here on this blog as to how I’m doing with that.


By Mike October 13th, 2009, under Uncategorized

I’ve always been interested in the upper UHF and microwave amateur radio bands (900 MHz and up).  Unfortunately, nobody actually makes full-on radios for these bands (save for 1.2 GHz, and they’re expensive).  This leaves the curious amateur with two options:  build a radio, or build a converter to allow common radios to operate at higher frequencies.  The second option, obviously, is simpler and the route I decided to take.

I recently discovered W1GHZ’s multiband transverter project.  Essentially, his goal was to build inexpensive transverters that worked “well enough”–and ones that had an interchangeable LO to keep costs down.  Since I already own commercial 900 MHz gear that works on the 902-928 amateur band, I decided to order the 902 MHz transverter kit.  I should get the boards and parts in soon, and I’ll post again once I get it assembled and tested.  Here’s hoping it works well!

Technical Topics for Wireless Mics

By Mike September 18th, 2009, under Wireless Mics

This section goes into detail on some of the more technical topics relating to wireless microphones.
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Frequency Selection for Wireless Microphones

By Mike September 18th, 2009, under Wireless Mics

Frequency coordination is essential to the proper function of wireless systems. Not only must channels be sufficiently spaced apart, but they must also be checked to ensure that they will not interfere with each other if the RF signals become distorted. This phenomenon, commonly referred to as \emph{Intermodulation distortion}, occurs when signals pass through nonlinear devices such as amplifiers and receiver circuits. Finally, channels must be selected to avoid television stations (both analog and digital), and also two-way radio systems operating in certain cities.
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The Big Picture – What’s in a Wireless System?

By Mike September 18th, 2009, under Wireless Mics

Wireless systems consist of a number of components. Transmitters and receivers are the most obvious of these componenets, but coaxial cable (sometimes referred to as transmission line), antenna splitters, amplifiers, and antennas also contribute to wireless systems. In this section, we will discuss these components in depth.
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