What I Learned About Radio Repair
Read What Phil Says About This
This
is a quick and dirty summary of my knowledge of old radio repair and may this
provide some answers to frequently asked questions by newcomers to the radio
restoration hobby. Radio repair is expensive to have done, that’s why I’m
learning it myself. I also really enjoy working with vintage electronics.
I learned that vacuum tubes aren’t the only things that
cause an old radio to quit. Radios are incredibly complex circuits with
many parts. Tubes are just a small fraction of what it takes to build a
radio receiver. Tubes can burn out, true, but what causes them to burn
out is what needs to be investigated and repaired.
Capacitors fail
and either fail to pass current (they’re said to be “open”) or they pass
current directly, free from obstruction, or just simply short. Capacitors
can also burn up. So can transformers. Transformers usually
burn up because the capacitors are shorted. Are you lost yet? The
only way to know what I’m talking about is to read about radios and electrical
theory. Replacing the capacitors in old radios as well as replacing bad
resistors is the first stage in restoration (assuming the transformer is still
good). The last thing is replacing tubes. Some, if not all, of the
tubes in an old set you find may still be good. How do you know?
Buy a tube tester. I can guarantee you won’t find a tube tester at any
local electronics store. Because old radios run on high voltage (as
opposed to low-voltage for solid-state, or transistorized, electronics) you
will find almost nothing usable for purchase locally. Almost all parts
are special order through suppliers like Antique
Electronic Supply or Radio Daze.
Radio work requires tons
of equipment, books, knowledge, and experience. Radio equipment you’ll
need to get started includes a soldering iron, a tube tester, an ohm/voltage
meter, an RF generator, and an isolation transformer for safety, electrical
contact cleaner, and the list goes on. This stuff isn’t cheap. What
makes this process even more complicated is that some of these tools are only
available through special-order and some haven’t been made in at least the past
30 years. Next you have to learn how to use all these tools. That
requires reading- LOTS of reading. Keep in mind radio is the least
complicated of electronic devices from the past. Televisions are even
more difficult to repair.
Finding good books on radio repair requires hunting at flea
markets and antique bookshops, and of course your local library. Many libraries still have books on
radio repair that are 40+-years-old. There are modern books about old
radio repair, but I’ve found the best books were written when these sets were
new, that is, books from the 1920s-1960s.
Tubes are easily
available and most tubes (for the majority of surviving old radio sets
and other electronics 1930-present) are cheaper today than they ever have
been (in terms of both nominal values and real values!) Reasons for
this are simply supply and demand. Conservative estimates say that at our
current rate of use, we’ll have enough vacuum tubes to last us the next
thousand years. Certain high-demand and common tubes are still being made
in China and Russia, because certain modern day electronics are built to use
tubes, collectors need them, and many nations are still using vacuum tube
equipment out of necessity. Think of all the antique radios that still
exist and are being used on a daily basis. There are hardly any.
Most collectors just buy sets to display, not to use. This means that nobody is
really using the supply of vacuum tubes up anyway. When I buy radio
tubes, they usually don’t cost me any more than $6, sometimes they’re under $2.
Most tubes that people find today are for televisions from
the 1950s-1960s. They’re practically worthless, but should not be thrown
away. If you have some, sell them
to an antique dealer, put them on Ebay, or e-mail me! These tubes are
about the size of a person’s thumb and have 9-10 pins on the bottom. They
shouldn’t be thrown out, in my opinion, but they aren’t worth a lot. Most
people want radio tubes from the 1920s-1940s. Few people are restoring
and using 1960s television sets. The reason these tubes are so prevalent
is that television repairmen would travel from house to house to fix TVs, which
were too heavy to carry in for service. Radios, on the other hand, would
be brought to the radio shop by their owners for repair. When TV
repairmen retired, they often took home and stored their supply for televisions
and unfortunately these tubes are not compatible with radios. Keep in mind
there were hundreds of types of tubes manufactured over a 40-year span.
I hope this helped you
to understand the very basics radio repair. It’s all about testing
components, research, studying schematics, and soldering, soldering, soldering.
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