K3 160M Diversity Users

[Michael Raskin]

I am about to order filters for the K3 and need some final advice.  I have
the capability for diversity reception on 160 and 80 and am wondering what
is the best filter pair to use for CW.  Price really doesn't enter into the
equation as a pair of matched 5-poles filters are about the same price as a
pair of 8-pole filters.  What are your recommendation if I were to get only
one pair of filters?  Is there any real value to getting a pair of narrow
(200Hz or 250Hz) filters as well as a pair of the wider (400Hz or 500Hz) CW
filters, or am I just wasting money?  Is there a noticeable difference
between the 5-pole and 8-pole filters?  I would appreciate hearing from
someone who has already gone through this and it would save me a lot of
mental anguish!

Mike, W4UM

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[Bill W4ZV]

W4UM wrote:

> What are your recommendation if I were to get only
one pair of filters?  

I would go with either the 500 or 400 8-poles.

> Is there any real value to getting a pair of narrow
(200Hz or 250Hz) filters as well as a pair of the wider (400Hz or 500Hz) CW
filters, or am I just wasting money?  

I have a 200 Hz in my Main in addition to 500 Hz 8-poles in Main and Sub.  If you contest or are in huge simplex pileups, there are definitely times when the 200 Hz may be useful.  For some reason I don't understand, I have no offset warbling when setting WIDTH to 200 (which enables the 200 Hz in Main and 500 Hz in Sub).  Most of the time when listening to weak signals, I use 350-500 Hz WIDTH so a pair of 500 Hz filters is fine excluding the extreme cases of simplex pileups or a strong station nearby (e.g. the CQ 160 CW contest).

> Is there a noticeable difference between the 5-pole and 8-pole filters?  

I used 5-pole 500s in my first K3 and have not noticed a significant difference with the 8-poles, but I've not compared them simultaneously.  As you stated, there's little cost difference (after the matching charge) so I went with the 8-pole 500 Hz when it became available.  I personally prefer a slightly wider BW than the 400 Hz allows but that's another option some choose.

You'll love diversity on 160 and 80, especially if you have good RX antennas.  I use my TX antenna (similar to a 4-square) in one RX and Beverages in the other, and I use diversity 99% of the time on the low bands.  I would never own any rig without diversity now that I've used it.

73,  Bill  W4ZV

[Gary Hinson]

> I am about to order filters for the K3 and need some final
> advice.  

Hi Mike.

I have a pair of 400Hz and a pair of 250Hz 8 poles in my K3.  I'm
pretty active, 99% CW, and rarely use the 400Hz (maybe once a day) and
very rarely the 250Hz (once a week).  The DSP works extremely well.
So of these, I'd recommend the 400Hz, and save up for the 250's later
if you decide you need even narrower bandwidth than the 400+DSP can
achieve.  

The 8 poles probably have a better shape factor than the 5 poles,
judging by my experience comparing the 5 pole stock Kenwood filters
with the 8 pole IRC replacements in my old TS850.  With the DSP, I'm
not sure you'd notice the difference but as you see I went for the
better filters and don't regret it.

On extremely rare occasions (e.g. fishing out CW callers in SSB QRM
from Indonesian pirates) I have wound the filters right down to the
minimum 50Hz and even at that ridiculously narrow setting, the K3 is a
joy to copy with no appreciable ringing - miles better than the TS850
and indeed any other rig I've tried.  

I also use diversity with a 30m fullwave loop.  Works great!

I'm thinking of getting the AM and/or FM filters next so I can open up
the bandwidth to listen to a whole chunk of band at once using an AF
spectrum program: it sometimes helps to listen to all the callers in a
pileup and to choose a clear slot to call.

73,
Gary  ZL2iFB



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[Joe Subich, W4TV-4]

> The 8 poles probably have a better shape factor than the 5
> poles, judging by my experience comparing the 5 pole stock
> Kenwood filters with the 8 pole IRC replacements in my old
> TS850.  With the DSP, I'm not sure you'd notice the
> difference but as you see I went for the better filters and
> don't regret it.

The 8-pole filters do have significantly better shape factor
but mostly at the lowest levels on the filter skirts.  For
the most part you will never see the difference as the DSP
has an almost rectangular response.  

You're not likely to see any real difference between the 500 Hz
5-pole and 400 Hz 8-pole filters in practice.  I've measured the
-6dB bandwidth of the 500 Hz 5-pole filters in both of my radios
at just under 500 Hz and the -30 dB bandwidth at about 760 Hz.  
This compares to the published data of 435 Hz @ -6dB and 650 Hz
@ -30 dB for the 400 Hz 8-pole filters - see:
www.elecraft.com/K3/K3_8_pole_plots.htm or
www.inrad.net/product.php?productid=150&cat=140&page=1

73,

   ... Joe, W4TV
 

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Gary Hinson
> Sent: Saturday, July 25, 2009 1:43 AM
> To: [hidden email]
> Subject: Re: [Elecraft] K3 160M Diversity Users
>
>
> > I am about to order filters for the K3 and need some final
> > advice.  
>
> Hi Mike.
>
> I have a pair of 400Hz and a pair of 250Hz 8 poles in my K3.  
> I'm pretty active, 99% CW, and rarely use the 400Hz (maybe
> once a day) and very rarely the 250Hz (once a week).  The DSP
> works extremely well. So of these, I'd recommend the 400Hz,
> and save up for the 250's later if you decide you need even
> narrower bandwidth than the 400+DSP can achieve.  
>
> The 8 poles probably have a better shape factor than the 5
> poles, judging by my experience comparing the 5 pole stock
> Kenwood filters with the 8 pole IRC replacements in my old
> TS850.  With the DSP, I'm not sure you'd notice the
> difference but as you see I went for the better filters and
> don't regret it.
>
> On extremely rare occasions (e.g. fishing out CW callers in
> SSB QRM from Indonesian pirates) I have wound the filters
> right down to the minimum 50Hz and even at that ridiculously
> narrow setting, the K3 is a joy to copy with no appreciable
> ringing - miles better than the TS850
> and indeed any other rig I've tried.  
>
> I also use diversity with a 30m fullwave loop.  Works great!
>
> I'm thinking of getting the AM and/or FM filters next so I
> can open up the bandwidth to listen to a whole chunk of band
> at once using an AF spectrum program: it sometimes helps to
> listen to all the callers in a pileup and to choose a clear
> slot to call.
>
> 73,
> Gary  ZL2iFB
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

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[Joe Planisky]

Hi Gary,

Do keep in mind that in CW mode, the maximum audio bandwidth is  
limited by the DSP to 2.8 kHz even if you have the AM or FM roofing  
filter installed.  Even in phone modes, the audio rolls off somewhere  
around 4 kHz, so that would give you a fairly narrow chunk of the band  
at audio.

73
--
Joe KB8AP

On Jul 24, 2009, at 10:43 PM, Gary Hinson wrote:

...
>
> I'm thinking of getting the AM and/or FM filters next so I can open up
> the bandwidth to listen to a whole chunk of band at once using an AF
> spectrum program: it sometimes helps to listen to all the callers in a
> pileup and to choose a clear slot to call.
>
> 73,
> Gary  ZL2iFB

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[wc1m]

My experience pretty-much aligns with Bill's. I started out with matched
pairs of 5-pole 500 Hz and 5-pole 200 Hz filters. The 500/200 combination
makes a little more sense than the 400/250 combination because there's more
difference between the filter widths.

Like Bill, I rarely use the 200 Hz filters. Most of my use is contesting. If
you spend too much time with BW cranked down to 200 Hz or less, you're going
to miss a lot of callers. I only use narrow BW when someone plops down very
close to my frequency when I'm in the middle of a QSO. That said, the narrow
BW saves me every now and then, which for me is worth the cost.

I was fairly satisfied with the 5-pole 500 Hz filters, but was sometimes
bothered by thumping and clicking from loud stations (S9 and higher) just
above my passband. This is likely caused by the hardware AGC activating at
somewhat too low a level. Quite a while ago there was a fix to the RF board
to raise the threshold, but some of us think it's still too low.

At any rate, though the theory says that roofing filters aren't responsible
for the ultimate selectivity (the DSP does that), I found that they do make
a difference in the above situation. Switching off the 500 Hz filters and
using the 200 Hz filters produced audibly less interference, most likely by
providing greater attenuation at the hardware AGC stage. That induced me to
replace the 5-pole 500 Hz filters with 8-pole 400 Hz filters.

The result was a minimal improvement, not easily detected by testing. The
real test will come this fall when I'm squeezed into 40m or 20m with
zillions of loud stations on either side.

All that said, Bill is correct that, with the matching fee, the price
difference between 5-pole and 8-pole filters is small enough that it makes
sense to get the 8-pole filters. I should note that the 8-pole filters are
not necessarily perfectly centered, but they're close enough that you
probably won't need to use any offset for diversity.

As far as the 200 Hz vs 250 Hz filters go, if you want to have them in
reserve for those really tough QRM situations, I would get the 5-pole 200 Hz
filters. Elecraft says they're narrower than the 250 Hz filters all the way
down. Also, there's more BW difference between the 200s and the 400s/500s.

I agree completely with Bill on the merits of diversity: with the right
antennas, it's amazing.

73, Dick WC1M

> -----Original Message-----
> From: Bill W4ZV [mailto:[hidden email]]
> Sent: Friday, July 24, 2009 10:27 PM
> To: [hidden email]
> Subject: Re: [Elecraft] K3 160M Diversity Users
>
>
> W4UM wrote:
>
> > What are your recommendation if I were to get only
> one pair of filters?
>
> I would go with either the 500 or 400 8-poles.
>
> > Is there any real value to getting a pair of narrow
> (200Hz or 250Hz) filters as well as a pair of the wider (400Hz or 500Hz)

CW
> filters, or am I just wasting money?
>
> I have a 200 Hz in my Main in addition to 500 Hz 8-poles in Main and Sub.
> If you contest or are in huge simplex pileups, there are definitely times
> when the 200 Hz may be useful.  For some reason I don't understand, I have
> no offset warbling when setting WIDTH to 200 (which enables the 200 Hz in
> Main and 500 Hz in Sub).  Most of the time when listening to weak signals,
I
> use 350-500 Hz WIDTH so a pair of 500 Hz filters is fine excluding the
> extreme cases of simplex pileups or a strong station nearby (e.g. the CQ
160
> CW contest).
>
> > Is there a noticeable difference between the 5-pole and 8-pole filters?
>
> I used 5-pole 500s in my first K3 and have not noticed a significant
> difference with the 8-poles, but I've not compared them simultaneously.
As
> you stated, there's little cost difference (after the matching charge) so
I
> went with the 8-pole 500 Hz when it became available.  I personally prefer
a

> slightly wider BW than the 400 Hz allows but that's another option some
> choose.
>
> You'll love diversity on 160 and 80, especially if you have good RX
> antennas.  I use my TX antenna (similar to a 4-square) in one RX and
> Beverages in the other, and I use diversity 99% of the time on the low
> bands.  I would never own any rig without diversity now that I've used it.
>
> 73,  Bill  W4ZV
> --
> View this message in context:

http://n2.nabble.com/K3-160M-Diversity-Users-
> tp3322951p3323855.html
> Sent from the Elecraft mailing list archive at Nabble.com.


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[Joe Subich, W4TV-4]

> All that said, Bill is correct that, with the matching fee,
> the price difference between 5-pole and 8-pole filters is
> small enough that it makes sense to get the 8-pole filters.

This is particularly true if you are buying multiple filters.
With the discount for three (5%) or five (10%) filters, the
direct route is less expensive than including the filters with
the transceiver.  

> I would get the 5-pole 200 Hz filters. Elecraft says they're
> narrower than the 250 Hz filters all the way down.  

Close enough ... measurements of my 200 Hz filters "in circuit"
show 210 Hz @ -6dB and 840 Hz @ -50dB (I need to repeat the
measurements with the preamp to extend the range) versus the
published data (www.elecraft.com/K3/K3_8_pole_plots.htm) for
the 250 Hz filters: 370 Hz @ -6dB and 785 Hz @ -60dB.

73,

   ... Joe, W4TV
 

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Dick Green WC1M
> Sent: Saturday, July 25, 2009 1:30 PM
> To: 'Bill W4ZV'; [hidden email]
> Subject: Re: [Elecraft] K3 160M Diversity Users
>
>
> My experience pretty-much aligns with Bill's. I started out
> with matched pairs of 5-pole 500 Hz and 5-pole 200 Hz
> filters. The 500/200 combination makes a little more sense
> than the 400/250 combination because there's more difference
> between the filter widths.
>
> Like Bill, I rarely use the 200 Hz filters. Most of my use is
> contesting. If you spend too much time with BW cranked down
> to 200 Hz or less, you're going to miss a lot of callers. I
> only use narrow BW when someone plops down very close to my
> frequency when I'm in the middle of a QSO. That said, the
> narrow BW saves me every now and then, which for me is worth the cost.
>
> I was fairly satisfied with the 5-pole 500 Hz filters, but
> was sometimes bothered by thumping and clicking from loud
> stations (S9 and higher) just above my passband. This is
> likely caused by the hardware AGC activating at somewhat too
> low a level. Quite a while ago there was a fix to the RF
> board to raise the threshold, but some of us think it's still too low.
>
> At any rate, though the theory says that roofing filters
> aren't responsible for the ultimate selectivity (the DSP does
> that), I found that they do make a difference in the above
> situation. Switching off the 500 Hz filters and using the 200
> Hz filters produced audibly less interference, most likely by
> providing greater attenuation at the hardware AGC stage. That
> induced me to replace the 5-pole 500 Hz filters with 8-pole
> 400 Hz filters.
>
> The result was a minimal improvement, not easily detected by
> testing. The real test will come this fall when I'm squeezed
> into 40m or 20m with zillions of loud stations on either side.
>
> All that said, Bill is correct that, with the matching fee,
> the price difference between 5-pole and 8-pole filters is
> small enough that it makes sense to get the 8-pole filters. I
> should note that the 8-pole filters are not necessarily
> perfectly centered, but they're close enough that you
> probably won't need to use any offset for diversity.
>
> As far as the 200 Hz vs 250 Hz filters go, if you want to
> have them in reserve for those really tough QRM situations, I
> would get the 5-pole 200 Hz filters. Elecraft says they're
> narrower than the 250 Hz filters all the way down. Also,
> there's more BW difference between the 200s and the 400s/500s.
>
> I agree completely with Bill on the merits of diversity: with
> the right antennas, it's amazing.
>
> 73, Dick WC1M
>
> > -----Original Message-----
> > From: Bill W4ZV [mailto:[hidden email]]
> > Sent: Friday, July 24, 2009 10:27 PM
> > To: [hidden email]
> > Subject: Re: [Elecraft] K3 160M Diversity Users
> >
> >
> > W4UM wrote:
> >
> > > What are your recommendation if I were to get only
> > one pair of filters?
> >
> > I would go with either the 500 or 400 8-poles.
> >
> > > Is there any real value to getting a pair of narrow
> > (200Hz or 250Hz) filters as well as a pair of the wider (400Hz or
> > 500Hz)
> CW
> > filters, or am I just wasting money?
> >
> > I have a 200 Hz in my Main in addition to 500 Hz 8-poles in
> Main and
> > Sub. If you contest or are in huge simplex pileups, there are
> > definitely times when the 200 Hz may be useful.  For some reason I
> > don't understand, I have no offset warbling when setting
> WIDTH to 200
> > (which enables the 200 Hz in Main and 500 Hz in Sub).  Most of the
> > time when listening to weak signals,
> I
> > use 350-500 Hz WIDTH so a pair of 500 Hz filters is fine
> excluding the
> > extreme cases of simplex pileups or a strong station nearby
> (e.g. the
> > CQ
> 160
> > CW contest).
> >
> > > Is there a noticeable difference between the 5-pole and 8-pole
> > > filters?
> >
> > I used 5-pole 500s in my first K3 and have not noticed a
> significant
> > difference with the 8-poles, but I've not compared them
> > simultaneously.
> As
> > you stated, there's little cost difference (after the
> matching charge)
> > so
> I
> > went with the 8-pole 500 Hz when it became available.  I personally
> > prefer
> a
> > slightly wider BW than the 400 Hz allows but that's another option
> > some choose.
> >
> > You'll love diversity on 160 and 80, especially if you have good RX
> > antennas.  I use my TX antenna (similar to a 4-square) in
> one RX and
> > Beverages in the other, and I use diversity 99% of the time
> on the low
> > bands.  I would never own any rig without diversity now
> that I've used
> > it.
> >
> > 73,  Bill  W4ZV
> > --
> > View this message in context:
> http://n2.nabble.com/K3-160M-Diversity-Users-
> > tp3322951p3323855.html
> > Sent from the Elecraft mailing list archive at Nabble.com.
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html

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