On 3/29/2012 1:27 AM, Ed Muns wrote:
> "Lying to your K3" may be cute to say, but it detracts from what is
> really going on.
"Lying to your K3" is the correct term in one case ... telling the K3
that the 13 KHz FM filter is a 6 KHz AM filter so one can transmit AM
and/or ESSB. I still don't understand why it is necessary to do that
after all this time. If the transmit image suppression is sufficient
for FM it should be more than sufficient for AM and I certainly can
not see any image when I look for it with a directional coupler and the
SDR-IQ.
Filter slots are too precious. If one is to have "normal" and "narrow"
options for both SSB and CW that leaves but one free slot to cover both
FM and AM/ESSB.
73,
... Joe, W4TV
On 3/29/2012 1:27 AM, Ed Muns wrote:
> "Lying to your K3" may be cute to say, but it detracts from what is really
> going on. That filter parameter simply sets the DSP bandwidth at which the
> crystal filter engages, and for all narrower bandwidths until the next
> crystal filter engages. The crystal filter and the DSP filter can have
> three basic relationships, all with different results. One filter can be
> significantly wider than the other or they can be close to the same
> bandwidth. There are lots of K3s configured in each of these three ways and
> the users that understand the implications of their particular choice will
> have one or more reasons for that choice. One popular reason for engaging
> the crystal filter at a significantly wider DSP bandwidth, is that the shape
> of the audio passband is "rounder" (because it is dominated by the crystal
> filter passband shape) and sounds a bit different than when the more
> rectangular DSP passband dominates, i.e, is narrower than the crystal
> filter. One popular reason for engaging the crystal filter when the DSP
> bandwidth is well inside it, is to maintain consistent bandwidth steps as
> the K3 IF bandwidth is varied via the WIDTH or HI/LO-CUT controls. Users
> that care about this usually don't confuse the marketing name of the filter,
> e.g., 250 Hz, with the actual bandwidth, e.g., 370 Hz.
>
> Ed - W0YK
>
>
>
>
> Mike, KE5GBC, wrote:
>> Don, I thought the comment rather " tongue in cheek". Some
>> consider all caps akin to cursing.
>>
>> As to lying to the k3 as to the filter you have put in it's
>> slot which I think more than a few do.
>> If you have told the k3 that it's a 2.1 but it's actually 1.8
>> and you have dsp set to 2.1, isn't it actually 1.8 and lying
>> to yourself? No offense meant.
>>
>> Is there some advantage to this other than allowing one to
>> jump filter to filter like the old days?
>>
>> I have seen reference to cascading filters but isn't that
>> having the dsp the same as the filter? Could someone as to
>> before mentioned benefit and cascading filters to clear this
>> up for me.
>> I don't see the point in lying to the k3 but wonder if I'm
>> missing a valuable tool?
>
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