[Elecraft] Determining best roofing filter with DSP??

[Dick Dievendorff]

A 2.7 kHz 5-pole filter is included with each K3 and each KRX3.  (See the K3
price list/order form at http://www.elecraft.com/elecraft_prod_list.htm#k3)

You may replace that 2.7 kHz 5-pole filter with a 2.8 kHz 8-pole filter at
the time of initial order for an additional amount that is slightly less
than a new 2.8 kHz filter. (see the KFL3A-2.8_2.7sw item on the K3 order
form).   

If you're ordering both main and sub, you should consider "matching" the
filters if you decide on the 2.7 kHz 5-pole filters. (see KFLMATCH on the
order form). Matching is not required for two 2.8 kHz 8-pole filters.

A 2.7 or 2.8 kHz filter is required in the main K3. It is used as the
transmit filter for CW, Data and SSB modes. Even if you're a 100% CW
operator, you'll need one of these two filters, 2.7 or 2.8 kHz, on the K3
main RF board.

If you're uncertain, the smallest initial investment would be to order the
"default" 2.7 kHz 5-pole filters for both main and sub.  If you plan to use
diversity, investing in a matched pair would be a good idea.  Some users
feel that starting with two 2.8 kHz 8-pole filters is a better investment
than the matching fee.  Others are quite happy with the 2.7 kHz 5-pole
filters.

I chose 2.8 kHz 8-pole filters as my initial filters in main and sub.

If you're primarily a CW operator, you should also consider a narrow filter,
somewhere around 400-500 Hz.  There are several to choose from; Elecraft
offers a 400 Hz 8-pole filter and a 500 Hz 5-pole filter, and I think Inrad
may offer a 500 Hz 8-pole filter.  

You don't have to get this right on day one.  You can start with what you
know you need and add filters later.

73 de Dick, K6KR



-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of callen1155
Sent: Wednesday, February 24, 2010 2:30 PM
To: elecraft at mailman.qth.net
Subject: [Elecraft] Determining best roofing filter with DSP??



Hello guys.

Sorry about all the questions but I think this is the last one before I
press the "buy" button for a K3.

Once again a question about cw roofing filters.

I am initially ordering the K3 without the 2nd receiver but do plan on
getting one within a year. 

That said, and knowing it's best to have 'matching roofing filters' for both
receivers, even after all the reading I still have no idea what would be the
best roofing filter to get. It seems to be such an individual choice.
Ideally, I'd prefer to purchase only one filter (or one for each receiver)
and want to make the best filter choice for my operating. 

So if I order the K3 with no roofing filters, can I determine from operating
with just the DSP which cw roofing filter would be the optimal one for me.

Or is the above an exercise in futility and I just need to order say a 400
and see how that does before I'll know? 
But then again I guess it wouldn't be 'matched'' when I get one for the
second receiver.

Too many decisions!

thanks again.
chuck
af4xk