[Milsurplus] re: commercially converted surplus radio gear (BC 433) (long)

[BOEING377@aol.com]

Thanks to the generosity of Jack (SCR 287) I obtained a commercially 
converted BC 434 control box for the BC 433 Radio Compass (ADF). The 
converted control box has a 2-3 Mc marine band for band 3 instead of the 
standard 850 Kc to 1750 Kc. It is so well done that you would almost think it 
was done by the mfr. A new engraved dial, new lithographed metal faceplate 
for the band switch, all done in appropriate lettering to make you think it 
is stock military. This is exactly the box I remember seeing on  commercial 
fishing boats. NEVER thought I would see one again much less obtain one. Jack 
just gave it to me, no strings. I'll find something nice to send him. What a 
great guy!

Somebody went to a lot of trouble converting these BC 433s. The professional 
attn to detail almost made me wonder if they were perhaps done for US Coast 
Guard planes, but as far as I know they were intended solely for the 
commercial fishing market. I do know that they worked very well for DFing AM 
marine band comms. 

A lot of money could be made finding other boats that were catching fish but 
not disclosing their good fortune or location in plain language. My dad paid 
for his DF in one day a couple of times by shooting bearings on other boats 
who were secretly making a killing.  You had to be part psychologist to pick 
up the "too nonchalant, too calm" tone of voice in the guy calling his friend 
and saying fishing was real slow. 

Our ADF was a converted ARN 7, done by me as a high school kid.  ARN 7 was 
quite a bit like the BC 433, but had 4 bands starting at 100 Kc instead of 
200 Kc. Also, the ARN 7 had a ratchet band switch motor that was loud and 
sounded like a machine gun when picked up by a mic while transmitting. The BC 
433 had a quiet rotary motor gear driven bandswitch. 

Our ARN 7 worked great, but my C 4 ARN 7 control box was no competition for 
the BC 434 that Jack sent me. I just penned in a couple of marks on the band 
4 dial to indicate where 2182, 2638, 2738 Kc and other marine freqs could be 
found on a dial that still had BC band freqs on it. My conversion was pretty 
simple, just took some turns off the band 4 osc coil and realigned by ear and 
ref to the signal meter on the control box, no sig gen, no VTVM. 

The BC 433 professional conversion may have been more complex. The BC 434 
band 3 is 2.0 -3.0 Mc and fills up the entire dial. I dont even know what my 
band 4 coverage was after my conversion, just fooled with things til I could 
get 2638 Kc comms in the middle and 2182 (distress freq) somewhere near the 
lower end. Made some pen marks on the dial and called it quits. We had a 
working ADF for under $100 and my dad was happy. To him it was all about 
catching fish, this neat surplus stuff was just a tool. To me, the tools held 
a special fascination and led to an EE degree.


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