RCA Radiomarine AR-8712 radio direction finder
The AR-8712 is the gold-faced RDF to the right. This is a common
unit from the mid 1950's. it receives on
broadcast, beacon and "marine"... being "interpreted" as 1.7 to 3.4 MHZ
in this case.
I got this one for under $10, as it was advertised as non-working, and
has bad paint, some rust, and pencil marks on the panel. Scrawled is
"Weather-3.0". This is a unit that got much use.
Of course I plugged it in when I got it. If the power cap spilled it's
guts, no harm, no foul... it should be replaced anyway. But everything
was fine... and when I wiggled a couple of tubes, I first heard
static... then voices! Garbled though... and the next image will
explain this.
It has a nifty spring post for an external antenna, so I hooked up my
100' longwire and tried the marine (SW) band. You can see the red lead
under the upside-down RDF antenna. And to my surprise, the SW works,
too.
Garbled speaker, garbled speech. The real suprise is that I could hear
any speech at all, because the coil magnet was completely frozen around
the permanent magnet. I had to wiggle it out with a pliers after this
pic was taken. I suppose it "worked" when the whole speaker sort of
vibrated, making some approximation of sound.
I'm going to try to re-cone the speaker if I can, using the original
coil and spider. The spider is bronze mesh, and perfect. After cleaning
around the sides of the magnet, I may be able to center and glue the
coil back to the spider... then glue a new cone to the coil tube.
Since posting the above images a couple
of years ago, I was lucky to find another ET-8712 in
fine shape. It does need a cleaning and repaint, but works fine and has
no major problems. I think the project shown here will be on the back
burner for a time. So it goes.
Radiomarine ET-8056 marine radiotelephone, which I just won
on eBay. But I have always assumed that this unit is the "sister" unit
to
the above RDF. The only major difference is that the radiotelephone
does not appear to have the ribbed front panel... this appears to be
smooth. Other than that, the log badge, speaker grill, tuning dial,
knobs, cabinet shape... all appear to be the same as the
RDF. I think I have seen the two of them together in the same ad, but I
have to dig around my Yachting magazines to see for sure.
It will make a nice matching set for display.
