[ARC5] RAX If Frequency

[Hubert Miller]

I will guess the 456/2 BFO of the GRC-9 was for stability  and/or  anti-pulling. The RU receiver also uses BFO at F/2.
This doesn't seem very common, though. I don't recall the BC-1306 manual mentioning such. 
I noticed some Japanese receivers that tune up to about 6 MHz use an IF around 750 kHz. There are a couple Japanese
comm receivers including the "HRO type" that use plug-in IF coils to change the IF for the low or high range tuning coils.
The Squires-Sanders SSR-1 ham bands and SSIBS shortwave broadcast use a 1000 kHz IF and interestingly, derive their
AM selectivity entirely from high-Q IFs at this frequency. Someone told me this rec. is difficult to work on out of its 
cabinet because the 1000 kHz MW broadcast stations are received well.
I recall years ago, probably the early 1980s, on a vacation up to the San Juan islands north of Seattle, using a transistor
broadcast radio, I heard unmistakable CW loud in the background. Apparently some merchant vessel on the 600 meter
band. I have never seen any transistor entertainment radio with a 500 kHz blocking circuit, but this was not uncommon
in the better radios of the tube era.
-Hue Miller