Unless you are working in a contest situation, or when there are
nearby strong signals, you can use the bandwidth filter in the
DSP for most situations. The exceptions are:
You need something wider than the required 2.7KHz/2.8KHz
filter -- e.g
FM operation. In this case, get the 13KHz FM filter. With the latest
firmware, you will also be able to use that filter for
wide-band SSB
and AM transmit.
You want the last bit of performance. See below.
There are two modes of operation to consider, tuning and QSO.
During tuning, you will want a bandwidth which is wide enough so
you can find the other station's signal. Once you have the
station tuned in, you want filters a bit wider than the
bandwidth of the mode you are using to eliminate as much QRN and
QRM as possible.
With SSB and AM, where the bandwidth determines the quality of
the audio, there is a tradeoff between the minimum needed for a
QSO and the bandwidth which will give maximum listening comfort.
On SSB receive, I find I usually dial in about 2.3KHz, but
people's opinions differ widely here.
I find the 250Hz filter works well for PSK operation, which is
my primary mode of operation. I also have the 3.7KHz standard
filter and the 13KHz "FM" filter.
Consider waiting until you have used your K3 for a while before
deciding which filters to get. You can use the DSP bandwidths
you are using most often to identify the filters which will
compliment those bandwidths.
I don't know the bandwidths of the WSJT modes you are using or
the modes you use for 2M contesting, but the above guidelines
should get you into the right ballpark for any of them.
Cheers - Bill, AE6JV/1
On 12/15/12 at 6:34 AM, [email protected] (PETER
HUTCHISON) wrote:
I appreciate that this is somewhat of a thorny / subjective
issue but a search of the archives actually revealed very
little in the way of useful information.
I'm in the throes of putting together an order for a K3 kit
after being given the appropriate financial go-ahead. However,
the issue of suitable filters is still to be finialised hence
this plea for help.
What filters would be suitable for a station that is primarily
interested in WJST modes namely FSK441 and JT65B on 2m? Also,
some 2m contest working from the hills where just occasionally
there are some big, wide signals to contend with. Very little,
if any HF use is anticipated.
As I said earlier, this is a subjective issue but all opinions
will be of use as although I have the go-ahead the price of the
filters in the UK being what they are I don't want to make a
(costly) mistake!!
Peter G4URT
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