OPEN COMMUNICATION THE LATEST IN NETWORKING AND WIRELESS TECHNOLOGIES
■ BY LOUIS E. FRENZEL W5LEF
COMM KITS
A radio kit is a great way to get familiar
with electronics and communications.
When is the last time you built a kit? Or, have you ever built a kit? A kit is a
super way to get close to electronics, and building a communications kit like
a radio is more interesting and useful than other electronic devices. I have
built many kits over the years and a high percentage of them have been
radios. If you are looking for a way to explore electronics or to experiment
with radio-related technology, kits are the way to go. Here is a look at some
available comm kits and some tips on kit building in general.
SWL RADIOS
A great way to start with kit building is to make a
shortwave receiver. They are relatively easy to build and
shortwave listening is pretty interesting because of the
variety of stations out there. There are two SWL radios I
can recommend. One of these is the Ramsey Electronics
SR-2C (see Figure 1). It is an actual superheterodyne
radio with input filter, mixer, IF amplifier with AGC, and
an audio power amplifier output. The tuning range is 4 to
20 MHz which covers most of the really interesting
shortwave broadcasts. Tuning is done with a pot that
varies the DC bias voltage on a
varactor diode. A varactor is really
a voltage variable capacitor that
varies the local oscillator
frequency. That range is limited to
a few MHz, and the kit gives you
the option to select some
capacitor values and coil
adjustments that will give you the
range you want. I selected the 6
to 11 MHz range that has lots of
stations, as well as WWV’s 10
MHz time signal.
68
February 2012
