[Milsurplus] National R-1230 countermeasures receiver

HL zbyte at comcast.net
Sat Dec 10 00:16:22 EST 2011

Many, many thanks to those in the Milsurplus group who responded with recommendations and to Francesco Ledda with some critical PDF pages. 
Progress report:   With the help of a partial schematic, I traced all wires of the ten-pin power connector and then carefully applied voltages to confirm each traced connection.  Everything worked; all tubes lit up; and the receiver came to life. However, sensitivity was quite low, so, now every stage will have to be checked--a slow process to begin early next year --IF I can find a complete readable schematic.  Meanwhile, for anyone who might own this remarkable receiver, here are the Amphenol (Type 18-1) pin IDs with voltage/current measurements. Note that other versions of this receiver may have different pin allocations.

Pin A	115VAC (for the rear fan if installed)
Pin B	115VAC (for the rear fan if installed)
Pin C	175VDC (B+ at 250mA)
Pin D	7.3VAC 5.5A (reduced by internal resistor to 6.3VAC)
Pin E	7.3VAC 5.5A (reduced by internal resistor to 6.3VAC)
Pin F	no connection
Pin G	no connection
Pin H	Ground
Pin I		5VAC 330mA (for receiver lamps, other side grounded)
Pin J	18VAC 730mA (reduced to regulated 6.3VAC for V301 filament, other side grounded)

Again, if anyone has any readable schematic pages for either the R-1125/FLR or the R1230/FLR, please let me know. I am desperate!

73 Hal KK6HY

Website for receiver:  http://online.sfsu.edu/~hl/R-1230FLR.html

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