Impoverished Radio Experimenter #5
Oooh!
It's time to build one of those scary superhets. I get a kick out of the guys
who are terrified to try anything more complicated than a crystal set. But
I get a charge out of the equally frightened guys who will build a regenerative
receiver but never try a superhet.
Here you get details on building a three tube superhet that
is actually easier to build than 
the
regenerative receiver shown in Vol 4, but
easily outperforms it. Three inexpensive octal tubes plugged into plastic
relay sockets, driven by homemade IF transformers made from cardboard boxes
and aluminum foil, deliver signals that are more stable and far more easily
separated than any regen can. And you can power this radio with the simple
power supply shown in Experimenter Vol
1.
This radio is an adaptation of a circuit that appeared in QST
in August 1938. Then (and still today, I suspect) hams were terrified of superhets.
The authors demonstrated how easy it was to build a superior receiver they
could use 
on
the air. This is no more complicated than 
bolting
three simple radios together: a pentagrid converter, an IF amplifier, and
a detector/BFO.
You wind the IF transformers on cardboard cores taken from kitchen plastic wrap, put them inside of corrugated cardboard boxes covered with aluminum foil. The whole radio is mounted on a pine board. It's easy to tune, easy to adjust, and you'll discover in an instant why regenerative receivers were relegated to the dumpster.
You also get plans on how to build a simple three transistor
oscillator
that you use to align the receiver, and can use to align other receivers as
well. The most expensive component is the nine-volt battery.
You'll learn how to build a simple coil winder to make coil
winding easier
and a simple oscillator that you can use to check the frequency of junk IF
transformers found in the alley or at a flea market. And you'll be introduced
to the complexities of universal coil winding, and how it can be done today.
It's all here from winding the IF transformers, choosing the frequencies, winding the coils and getting the whole thing working. You have to try it. This is so much better than a regenerative, easy to build, and it's dirt cheap.
If you're a coward, keep building the same crystal set. But if you want to experience the same excitement that you did when you first heard a crystal set as a kid, then you have to move on and build bigger and better radios. And this is one you MUST try. It's great. You'll see.
No. 22938 ... $6.95
 | ||
 | | |
