[Milsurplus] BC-9 Loop Test: Scratching My Head

[Hubert Miller]

Per the manual, the tuning range is 74-76 meters. That equates to about a 100 kHz range – i don’t have any information
otherwise. So the set divides this into channels marked 1-10 – this again, per manual; i don’t have an actual one to check out.
Channels 1 and 10 are not to be used, per manual. But the channel spacing is around 10 kHz. As i suggested earlier, maybe it
will be possible to “calibrate” the set and pencil mark where the “correct” setting for transmitting is. Yes, this does require
retuning between transmit and receive.  Marking the dial with pencil ticks is not a no-no; per the manual the individual
working channel positions are to be marked with pencil, where they differ from the actual dial markings. Just an idea, i don’t
know how practical it is.
I recall i actually owned a BC-9 back around 1980. This may possibly be the same one Dave has. When i read that only one
in 10 or 15 VT-1’s could be expected to work in the RF tube slot, i think i realized i did not want to pursue that project. I have
a BC-148 right now, but it needs a replica antenna. I appreciate now how improved that circuit is over the BC-9, especially
the clever use of a bridge circuit in the receiver input, to limit receiver reradiation. I also have a BC-156, which has the same
package format, but has a built-in inductor for the single #10 transmitter.
In the unlikely case that someone here has a BC-148 with damaged meter, i think i have a spare or two, but hiding at the
instant. This is the meter with the metal covered meter face with a small cutout for viewing the pointer in one reading
area only.
I just looked at my SCR-131 ( BC-148 )  SCR-161 ( BC-151 ) manual  TM 11-237 and saw it was dated 1942 -  a surprise and
kind of a disappointment. The channel spacing is also the 10 kHz as earlier.
Inside it says, “This manual supersedes TR 1210-50, July 6 1932”.   So that is a long time for the BC-9 variants to rule
the roost.
-Hue

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