narrow filer. Most of the older generation of rigs set the carrier
... Joe, W4TV
> I generally agree with Joe's advice, but will differ here. Joe is right
> that full bandwidth (with the 2.7 or 2.8 kHz filter) is 2.8 kHz, but
> optimum spectrum for speech intelligibility with this bandwidth limit is
> 400 Hz to 3.2 kHz. This is fundamental stuff -- Bell Labs, probably the
> premier engineering institution on the planet back then, figured it out
> at least 100 years ago, and lots of research in the years since has
> confirmed it.
>
> I own 1.8 kHz roofing filters, but find them too narrow for my
> ear-brain. We're all different, so YMMV. I have a 2.1 kHz filter in one
> of my K3s, and like it. I rarely set my IF narrower than 2 kHz for SSB.
>
> As Joe has noted, RXEQ can be adjusted to tilt the response a bit. If
> like many of us old guys you have much hearing loss, you might want to
> boost the top octave band in RXEQ by 3 dB.
>
> There are two other issues at play here. First, the K3 has a pretty good
> but pretty small speaker. Second, chief engineer Wayne Burdick has
> strong roots in backpacking, so his audio stages tend to be a bit
> current starved.
>
> 73, Jim K9YC
>
> On 10/18/2017 5:31 PM, Joe Subich, W4TV wrote:
>>
>> > Is there some adjustment I’m missing?
>>
>> Try adjusting the center frequency (shift) or decreasing the Low Cut
>> (FL) and High Cut (FH) by similar amounts. In general, the important
>> spectrum for speech is 400 - 2200 Hz while simply "dialing down" the
>> width causes the Low Cut to raise too quickly.
>>
>> The K3/K3S nominal 2.8 KHz bandwidth is set at 100 - 2900 (FC = 1500).
>> Simply dialing the width down to 1.8 KHz results in a passband of
>> 600 - 2400 Hz (FC remains 1500 Hz). Adjusting FC down to 1250 or 1300
>> Hz will greatly improve the "clarity" of SSB.
>>
>> In addition, the K3 has a flat audio response while most rigs have a
>> slight raising characteristic (about 3 dB/octave). You can emulate
>> that response using the RX EQ. Set 0.05 = -16, 0.10= -16, 0.20= -6,
>> 0.40= 0, 0.80= +3, 1.60= +6, 2.40= +8, 3.20= +9 and the audio will
>> emulate "other rigs". You can also set 3.20 to -6 to minimize high
>> frequency noise.
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