When I crank the volume down to nothing, I get what I can only describe
as a "whine" out of the speaker or headphones, maybe 500-600 Hz. When I
spin the knob (tune the radio) it becomes modulated.
Anyone else see this effect? Most prominent when listening w/phones.
Still looking for noise blanker and additional modules. Thanks!
* Scott Rosenfeld NF3I Burtonsville, MD FM19 QRV 80-10/6/2/440 *
*** 6m 64 grids worked on 8 watts ** HF 138 cfmd * QRP-L #147 ***
** QRP ARCI #9054 ** DXCC/WAS/WAC ** 100% dipole powered HF/6m **
* 301-549-1022 h / 301-982-1015 w * 145.490- 147.225+ PL 156.7 *
Scott,
What you hear is the microprocessor/counter noise running through the
AF system. It is part ground loop and part lack of filtering on the
B+. As a quick fix, I suggest a 100 ohm resistor in series with your
headphones. With low impedance phones, the attenuation requires more
AF gain which then raises your effective S/N. It also cuts the high
frequency response a bit which is less fatiguing.
Dick, K4XU
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