Before I started this project always thought the BC-474
(SCR-288) was a bit of a Dog. Not built to MIL standards, odd
shape and size compared to the radios that came after and
underpowered for what it is. Looking at the design of the
receiver with only one stage of IF and the transmitter that
appears to be right out of the 1947 ARRL handbook I had low
expectations. Once I started working on it with its multiple
old style leaky capacitors and mysterious “Cap Pack” stuffed
full of the same I did not expect much.
Built up a BA-48 battery pack and got the receiver working
first, OK it’s not the most sensitive receiver but in CW works
well down to a couple micro volts and has good AVC action in
AM. Somehow the set reminds me of the old Navy TBX set but
unlike the TBX this receiver has a working AVC system, and the
audio quality is not that bad considering the entire receiver
only draws around 10 MA @ 90 volts being just about the same
as the TBX. Into a fifty Ohm load with only a couple hundred
volts for the transmitter developed a good couple watts in AM
or CW, spurious down at least forty Db on the second and did
not see any other artifacts. Ok, so the transmitter dose have
the issue with C13 being in the wrong place, the decaying CW
chirp when changing between transmit and receive in CW sucks
and will have to change that but all in all have to say
despite a lot of the ideas I had going into this I now see
that I was wrong. Have to say that in comparison to things
like the BC-654 or later GRC-9 this strange little radio more
then holds its own and, makes a fun little field QRP or Show
set up.
Ray F/KA3EKH
______________________________________________________________
Milsurplus mailing list
Home: http://mailman.qth.net/mailman/listinfo/milsurplus
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html