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Small Receiver improvements (was:Receiving on harmonics of Receiver LO?)

erik@...
 

Alan,

Thanks for the excellent article!
Some learnings from it: 

  • If I want a wide detection bandwith (say 192kHz of HDSDR I/Q detection) I need to reduce C3 till C6 from 100nF to say 3nF.
  • To reduce noise I should remove (short) resistors R26 and R27 (now 82 ohm)
  • To even further reduce noise I could remove R9, R10, R14 and R15 (10k) and short C9-C12 (1uF). Can this work with the opamps at 12V? I can keep IC5A/B biased at 6V but the instrumentation opamps (IC3 and IC4) seem to do the bulk of the amplification so these preferably also should be kept  at 12V to increase dynamic range, but with bias at 2.5V (instead of 6V) I will not get extra dynamic range.

I'm using the receiver with a magnetic loop amplified with 2 stage balance Norton amplifier. 




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Erik@Home