K3 with sub RX here. Both with stock 2.7kHz and five pole 500Hz
filters. Not a contester but haunt DX and DXped piles. I have a
neighbour 300 metres away with a 9+60 signal from another brand
transceiver that fills any band he is on with S5 noise, somewhat less on
adjacent bands but still there. Inclusion of a band filter between his
transceiver and linear cures the adjacent band problem. A visiting K3
at the same location being used on SSB whilst I was on CW was not known
to be on the band until I saw a spot. A quick check revealed that I
could get within +/- 35kHz before noise became a problem. At that point
I was till copying a VE SSB mobile at S2-3 without difficulty.
The nice thing about the K3 is you can tell it lies about the filter
setup, both width and offset. Both my unmatched filter pairs have
exactly the same offset, I told the K3 they had. As far as I am aware
this information is only used in the maths used to set the syth
frequencies to make sure the filters are suitably positioned with
respect to the desired audio passband. A 500Hz filter passband window
error of a few tens of Hz is not an issue. I believe the "matched"
filters are only good for 10Hz, could be wrong there.
Five pole works for me.
Regards,
Mike VP8NO
On 21/01/2015 02:55, Dr. William J. Schmidt, II wrote:
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: [email protected]
-----Original Message-----
From: Elecraft [mailto:[email protected]] 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 <[email protected]> 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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