[Elecraft] K3 Configuration Cookbook?

[Don Wilhelm]

Rich,

I suggest you consider your need for the 8 pole 2.8 filter first - 
remember that it is the DSP that does the real filtering, the roofing 
filter is only to keep strong offending signals out of the DSP front 
end.  On that basis, consider your operating desires - if you are heavy 
into SSB DX chasing or contesting where you will be operating on very 
crowded bands, then the 2.8 kHz filter may provide you with some small 
extra benefit, but if your operation is more casual than that, the 2.7 
kHz filter should be adequate.

I believe once you answer the question about the 2.7 vs. the 2.8 filter, 
the rest of your considerations will come naturally.

Actually the filters in the sub-receiver do not have to be matched 
unless you will be using diversity receive where the two receivers 
ideally would be matched not only in frequency, but in phase.  You will 
not notice any slight differences in the filter centers unless you use 
diversity receive.

If immediate budget is a concern, I suggest you consider the following:
Basic K3/10 or K3/100 with the 2.7 kHz filter.
Add the FM filter when you want to add FM capability (receive or 
transmit or both) - the FM filter can also be used for AM receive (the 6 
kHz filter is required for AM transmit)
Then add the KBF3 to give you general coverage and take full advantage 
of the AM receive capability.
At that point, decide whether you really need the sub-receiver.  You 
should also know enough by that time to select the needed filters for 
the subreceiver.
Add narrow filters as needed to support your operating conditions and 
desires.

Of course, all this ignores things like the KXV3 and the KAT3, but your 
station requirements for these will likely be different than anyone 
else's - look at the features each adds and select them on the basis of 
cost vs. utility in your station.

That is similar to my personal upgrade path for the K3 except I do not 
think I will ever want the general coverage because I have several 
transceivers that are capable of general coverage already and I will not 
be hunting for weak SW BC stations.  I am not likely to add the sub-RX 
because my casual operation does not provide enough added utility to 
justify the cost - but it may be added much later down the road 'just 
because'.

I hope that helps a bit - your choices will not be the same as mine, but 
perhaps this gives you some clues to the reasons why each option or 
filter is to be added.

73,
Don W3FPR




Rich wrote:
> Lets try this again with further explanation. I am retired and do not have an
> endless budget to upgrade the K3. The upgrades I make will depend on their
> cost – yet I want to progress toward the “ultimate” K3 and not end up with a
> box of high dollar “junk.” I would like to know what I need to do certain
> things and not buy unnecessary parts and/or not have everything I need.  I
> have read here that if you want the 8-pole filter on the second receiver
> that you need to have an 8-pole filter on the main receiver. Perhaps a few
> (but not every) examples will give you the idea. I do not think these are
> correct – that is why I am asking.
> 1.	Second receiver used only as general coverage receiver – desire to listen
> to AM, FM, and CW. The following is needed, at a minimum - 
>      a.	KRX3,
>      b.	KBF3,
>      c.	KFL3B-FM,
>      d.	KFL3A-6K - ??,
>      e.	KFL3A-2.7 - ??.
> 2.	 No second Receiver – Desire to add FM
>      a.	KFL3B-FM
>      b.	???
> 3.	No second receiver – desire to add second receiver WITH 2.8 8 pole filter
>      a.	KRX3,
>      b.	KFL3A-2.8
>      c.	KFL3A-2.8 – for main receiver - ??????
>      d.	What do I do with the old 5 pole filter,
>      e.	Or should I just order the 5-pole filter.
> 
> Does this give you a better idea?
> 
> As you can see, looking at all of the options and various configurations you
> (almost) need a spreadsheet!