|[AMRadio] Resurrection of ARC-5 receiver|
tonne at comcast.net
Wed May 14 15:30:07 EDT 2008
Jim et al:
A ballpoint pen case is my "tuning stick" for now
but thanks for the suggestion. Others suggested
copper or brass tubing and some variations on that.
But of far more interest to me is that I noted that this
receiver has AVC. Accordingly I found a teeny 25k
pot and used that for the "sensitivity" control (I think
most of us would now call it RF gain). And I found
a teeny switch to allow or disable the BFO. And
finally I figured out a way to adjust audio level. That
was, by the way, a 500 k pot from grid of 12A6 to
ground. There is a high-value resistor just ahead
of that and so I used the new pot to attenuate the
audio. Cut a piece of aluminum to fit in the "adaptor"
plate and mounted the parts. Finally a small 120 volt
AC to 12 volt AC power transformer from a defunct
wireless intercom matched (sort of!) the 300 ohm
output to 8 ohms for the speaker.
Now have it working from a 24 VDC supply, using the
original dynamotor for B+. Draws 3.5 amps at
startup and quickly settles down to 1.1 amps. Next
step is to get B+ from other than the dynamotor and
I will have my monitor radio for 3885 kc. Early in the
afternoon and only things on are some BC stations.
Took about 9 "shop" hours to get this stuff done,
counting an hour or two to get detailed conversion
info from the 'net.
- Jim WB6BLD
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