[Elecraft] [Bulk] 8 or5 Pole cw filters

[Dr. William J. Schmidt, II]

Well let's be clear here...

These are roofing filters, so you will only notice a difference in adjacent frequency rejection of loud signals... so if you live out in the country and don't have any loud stations near you, it’s not likely you will ever perceive a difference between 5 pole and 8 pole filters.   So the decision is driven more by the degree of loud stations operating adjacent to you... than by the type of operating you do.


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ 

Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois

Owner – Operator
Villa Grand Piton – J68HZ
Soufriere, St. Lucia W.I.
Rent it at: http://www.vrbo.com/487375

email:  bill at wjschmidt.com

-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Don Wilhelm
Sent: Tuesday, January 20, 2015 11:23 PM
To: Bill Coleman; Mike Zbrozek
Cc: Elecraft
Subject: Re: [Elecraft] [Bulk] 8 or5 Pole cw filters

Bill,

If you are not into 'hot and heavy' contesting or DXing in a pileup 
and/or diversity receive, you will find the 5 pole filters quite adequate.

The "problem" is that the 8 pole filters have a better slope factor and 
do not have an offset.
The offset is only important for diversity reception, and the slope 
factor is only important in situations where the band conditions are 
such that there are strong signals on adjacent frequencies -- as might 
be encountered in heavy contests or DX pileups.

So if you are not interested in having the optimum receive capability in 
DX pileups and heavy contesting situations, save your $$$ and use the 5 
pole filters.  Some of us are more casual operators, and the $$$ savings 
can be significant.

73,
Don W3FPR

On 1/20/2015 11:17 PM, Bill Coleman wrote:
>> On Jan 13, 2015, at 10:52 PM, Mike Zbrozek <k8xf4 at verizon.net> wrote:
>>
>> As a cw opr that is planning on buying a K3 next month I would
>> like to know how many cw ops use/prefer 5 or 8 pole cw filters?
>> Does anybody use the 1000 Hz 8 pole filter for hunting cq's then
>> switch over to a 500 or 400 Hz filter? And how many cw ops use a sharper 200 or 250 Hz filter?
>>
>> Tnx in Advance
>>
>> Mike Zbrozek, K8XF
> I’m going to buck the trend a little bit. I only have one 8-pole filter — the 13 kHz FM filter.
>
> I see posts from a lot of guys who have a radio full of 8-pole filters. That’s nice — if you can afford it. Those filters are expensive.
>
> During the five years I spent dreaming of owning a K3, I had thought I only wanted to have the 8-pole filters. However, my wife (the best XYL ever!) ordered a very stock K3 for me for Christmas, and it came with the 2700 Hz (5-pole) filter. Swapping out this filter after the fact for the 2800 (8-pole) filter is even more expensive than ordering it in the first place.
>
> Because of the expense, I used the stock filter for about six months before contemplating anything. I bought the 13 kHz filter because it gave me FM and AM receive and transmit capability. I got the 500 Hz (5-pole) filter because someone offered it on this list at a greatly discounted price.
>
> The key thing to remember about the K3 is that the DSP IS your filter! You don’t have to buy any of those expensive crystal filters. PERIOD. The radio works great with just the stock filter.
>
> Do the expensive crystal filters make a difference? Yes. The 500 Hz filter makes a difference. I’ve got it configured to kick in at 450 Hz. There’s a distinct difference in the audio background noise switching to 450 from 500. During the 160m CW contest, this filter knocks down a lot of adjacent channel interference. I’m glad I have a narrow roofing filter available for CW, PSK and RTTY work.
>
>

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