[Elecraft] [K3] Perfect for Field Day S&P ... Limited Production 700 Hz 8-Pole Filters

[Wes (N7WS)]

That's why on more than one occasion I've said that to evaluate a transceiver's 
receiver performance, instead of a couple of HP8663 signal generators, two other 
like transceiver transmitters should be used as the signal sources for the 
measurements, until that is, our transceivers have the spectral purity of '8663s.:-)

  On 3/1/2014 7:17 PM, Joe Subich, W4TV wrote:
>
> Fred,
>
> In general you are correct.  However, there is one other effect that
> the narrow roofing filters are not going to resolve - garbage from
> your neighbors in the form of key clicks, transmitted phase noise and
> IMD.  I see it every time my neighbor (.66 mi) comes on a band with
> his Icom POS ... phase noise an clicks +/- 20 KHz.  The K3 handles his
> fundamental just fine as little as 500 Hz away but the phase noise and
> clicks make any band almost unusable.
>
> 73,
>
>    ... Joe, W4TV
>
>
> On 3/1/2014 7:59 PM, Fred Jensen wrote:
>> If you can, help me out here Don ...
>>
>> These are roofing filters.  From my perspective, which is likely wrong,
>> their job is to restrict the bandwidth presented to the 2nd mixer [and
>> downstream ADC].  They are of most value when you have very strong [i.e.
>> geographically close] signals adjacent to the desired signal [That would
>> be WX6V for me :-)].  The ultimate BW is set by the DSP of course, but a
>> really strong adjacent signal can begin to activate the HW AGC in the K3
>> which affects the signal inside your DSP BW, or I think that's true. So,
>> it follows to me that, if you are plagued by KW neighbors, narrower
>> roofing filters can reduce that problem.  This could be true on FD or
>> any other closely spaced HF operations ... IF you have two stations on
>> the same band/mode.
>>
>> If you are not so plagued, I can't figure out why it really matters.  I
>> have the filter that came with the K3 and I bought one [2.7 and .5, I
>> don't remember which was which], I've had no difficulties.  Jim [WX6V]
>> and Jack KF6T [equally close] became non-problems when I got my K3 ...
>> even more so now that Jim has a K3 and phase-noise has disappeared. :-)
>>
>> I've got to be missing something here, and sadly, it wouldn't be even
>> close to the first time.
>>