[Milsurplus] LO radiation

[WA5CAB at cs.com]

The Radar Search Receivers AN/APR-1, AN/SPR-1 and RDO (38-3200 MC, Navy c. 
1943) and AN/APR-4 (38-4000 MC, AAF c. 1944) each have four plug-in tuning 
units.  The two lower frequency ones in each case have RF amplifiers and vacuum 
tube mixers.  The two higher frequency ones have inputs directly to crystal diode 
mixers (no RF amp.).

In a message dated 3/28/2005 1:05:40 AM Central Standard Time, jfor at quik.com 
writes: 
> IMO, 3 dB is on the low side. AFAIK, receivers where the antenna goes 
> directly
> into a mixer are a post WW II development. The first such design I am aware 
> of
> is a roughly 1965 Racal design where the RF is mixed with a LO somewhere in 
> the
> 30 to 70 MHz range, and later down converted again. This design has problems
> even with today's high intercept mixers and Racal and Harris receivers often
> require pre selectors.

Robert Downs - Houston
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