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Old 8th Apr 2020, 2:42 pm   #31
Radio Wrangler
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Default Re: Marconi C100 B28 vs. Eddystones

Quote:
Originally Posted by ORAWA01 View Post
But aren't all the sets with BFOs are not the best for SSB reception? They are good for CW. I think I read somewhere on this.
A normal SSB receiver has a 'Carrier insertion oscillator' which is usually a crystal oscillator offset from the IF filter and fed into a mixer (usually called a product detector in this position) where it converts the SSB signal in the IF down to audio.

A CW receiver has the same structure, except it is usual to have the 'carrier insertion oscillator' a variable frequency one. This allows the operator to vary the tone of the signal he's listening to for best comfort, and to move it around for a bit of variety. The variable CIO is usually called a BFO

The receiver intended for CW needs to have a wide enough IF to let an SSB signal through (about 3kHz compared to 200-600Hz for CW) and you just need to set the BFO for the right amount of offset on the appropriate side of the IF for USB/LSB and off you go.

Presence of a BFO doesn't mean a receiver can't do SSB, it may mean that it's a bit more work, that's all.

David
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