[Elecraft] [K3] Filters for mixed JT65 and JT9 HF

[Joe Subich, W4TV]

> If I am correct, then you can most certainly take advantage of your 6
> kHz AM filter which will limit your broadcast audio bandwidth to 3.0
> kHz.

That only applies in AM transmit because of the double sideband nature
of AM.  If you use the 6 KHZ filter for SSB/ESSB/DATA receive, the
entire filter passband is used for one sideband ... one edge of the
filter is placed at 50 Hz in SSB/ESSB or 200 Hz in DATA and the other
edge of the filter is 6+ KHz away from the carrier ... more than enough
for the 4200 Hz HF limit in the DSP.

73,

    ... Joe, W4TV


On 10/7/2013 7:31 PM, Charlie T, K3ICH wrote:
> I believe that figure of 3400 Hz is the AUDIO bandwidth which is
> equivalent to an AM bandwidth twice that, or 6.8 kHz.  If I am correct,
> then you can most certainly take advantage of your 6 kHz AM filter which
> will limit your broadcast audio bandwidth to 3.0 kHz.  The 15 kHz filter
> will get you an extra 400 Hz.of audio, but is probably not practical due
> to the excessive bandwidth.  Save that one for FM.
>
> 73, Charlie k3ICH
>>
>>
>> On 10/7/2013 4:51 PM, Joe Subich, W4TV wrote:
>>>
>>> On 10/7/2013 4:39 PM, Bob wrote:
>>>> Just be aware that current DSP firmware in the K3 limits the receive
>>>> bandwidth to something around 3400 Hz. So even if you have a wider
>>>> filter, like the 6 KHz AM filter, you will not be able to utilize the
>>>> full 4 KHz bandwidth of WSJT-X for JT65/MT9 modes.
>>>
>>>
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