Xtal Filters
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Hello all,
Today I received the 1.8 Kc 8 pole filter and installed it tonight. I did the configuration with the software tool used for firmware updates as well (also performed an update as well). All went OK, but I do have a feeling something is wrong or my ears/brains work a little different from the majority (yeh yeh I know...) When XFil 2.7 is selected together with the DSP at 2.7 Kc, the audio sounds great. When decreasing the BW with the DSP to 1.8 (but keeping the centre the same), the hardware filter is switched in at 1.8 Kc DSP setting. During the decreasing process I'm loosing "information" (Ofcourse!) but my feeling says too much. When during the decreasing process I also lower the centre freq, the excessive loss of "information" is compensated. This gives me the feeling as if the filter isn't centered anymore. First I thought this might have to do something with the Offset (-0.91 for a 2.7 5 pole filter) but nothing was written on the 1.8 Kc 8 pole filter. I just tried it, but that didn't compensate the excessive loss. During a process of decreasing bandwidth while listening to an SSB signal, I would appreciate if a shift of the centre-freq of the DSP is not required Any suggestion? 73's, Evert PA2KW _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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I just want to avoid confusion:
With "loss" I do not mean insertion loss of the filter (it can even be compensated with FLx GN) but information loss due to reduced BW. Sorry for the BW :-) 73's, Evert PA2KW -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Evert Bakker (PA2KW) Sent: Wednesday, May 21, 2008 23:58 To: 'Elecraft Reflector' Subject: [Elecraft] Xtal Filters Hello all, Today I received the 1.8 Kc 8 pole filter and installed it tonight. I did the configuration with the software tool used for firmware updates as well (also performed an update as well). All went OK, but I do have a feeling something is wrong or my ears/brains work a little different from the majority (yeh yeh I know...) When XFil 2.7 is selected together with the DSP at 2.7 Kc, the audio sounds great. When decreasing the BW with the DSP to 1.8 (but keeping the centre the same), the hardware filter is switched in at 1.8 Kc DSP setting. During the decreasing process I'm loosing "information" (Ofcourse!) but my feeling says too much. When during the decreasing process I also lower the centre freq, the excessive loss of "information" is compensated. This gives me the feeling as if the filter isn't centered anymore. First I thought this might have to do something with the Offset (-0.91 for a 2.7 5 pole filter) but nothing was written on the 1.8 Kc 8 pole filter. I just tried it, but that didn't compensate the excessive loss. During a process of decreasing bandwidth while listening to an SSB signal, I would appreciate if a shift of the centre-freq of the DSP is not required Any suggestion? 73's, Evert PA2KW _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Evert Bakker (PA2KW)
> During a process of decreasing bandwidth while listening to an SSB signal, I
> would appreciate if a shift of the centre-freq of the DSP is not required > > Any suggestion? Use HI CUT/LO CUT instead of SHIFT/WIDTH in SSB. As you adjust for best recovery, the 1.8 kHz filter will cut in when the difference between HI CUT and LO CUT is 1.8 kHz or less, and will be centered on the difference between them. 73, Lyle KK7P _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Evert Bakker (PA2KW)
Evert,
When using SSB, it is usually easier and better to use the HI CUT/LO CUT rather than width and shift. Just reducing the HI CUT will usually result in a narrowed bandwidth but maintains intelligibility. The BFO/Filter relationship should be preserved with the low end between 250 and 300 Hz for best intelligibility with a narrow SSB filter - using Hi Cut allows you to easily achieve that. You might want to tweak the Lo Cut setting a slight amount, but the bandwidth reduction for a SSB signal should be mostly from the high frequency end. 73, Don W3FPR Evert Bakker (PA2KW) wrote: > Hello all, > > > > Today I received the 1.8 Kc 8 pole filter and installed it tonight. > > I did the configuration with the software tool used for firmware updates as > well (also performed an update as well). > > All went OK, but I do have a feeling something is wrong or my ears/brains > work a little different from the majority (yeh yeh I know...) > > When XFil 2.7 is selected together with the DSP at 2.7 Kc, the audio sounds > great. When decreasing the BW with the DSP to 1.8 (but keeping the centre > the same), the hardware filter is switched in at 1.8 Kc DSP setting. During > the decreasing process I'm loosing "information" (Ofcourse!) but my feeling > says too much. When during the decreasing process I also lower the centre > freq, the excessive loss of "information" is compensated. This gives me the > feeling as if the filter isn't centered anymore. > > First I thought this might have to do something with the Offset (-0.91 for a > 2.7 5 pole filter) but nothing was written on the 1.8 Kc 8 pole filter. I > just tried it, but that didn't compensate the excessive loss. > > > > During a process of decreasing bandwidth while listening to an SSB signal, I > would appreciate if a shift of the centre-freq of the DSP is not required > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Evert Bakker (PA2KW)
Hi,
I am assuming that you are using SSB. For SSB, use the Hi Cut / Lo cut mode instead and adjust the Hi Cut for lower bandwidth. The Shift / Width mode is not suitable for SSB since it wants to keep the center frequency constant, while what you want in almost all cases is simply decreasing the high end of the passband, keeping the low cut at 300Hz or so. SSB with a low cut of 600Hz sounds extremely bad. For the same reason, I find the XFIL button unsuitable in SSB mode since it wants to "center" the new filter which again causes the low cut to be way to high. I still think some of the design choices for this rig are not optimal for SSB operators. Knut - AB2TC
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Thanks Knut, Lyle, Don, Steve and Bill,
It must have become clear that I'm a CW operator and was used to SHIFT/WIDTH already :-). SSB, different mind set eh.... I will check the "hiss" item and learn more. Thanks for support and info! 73's, Evert PA2KW BTW, a vary happy K3 user! It's the first radio (I had) that beats the beast (TR7A/R7A). -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of ab2tc Sent: Thursday, May 22, 2008 00:35 To: [hidden email] Subject: Re: [Elecraft] Xtal Filters Hi, I am assuming that you are using SSB. For SSB, use the Hi Cut / Lo cut mode instead and adjust the Hi Cut for lower bandwidth. The Shift / Width mode is not suitable for SSB since it wants to keep the center frequency constant, while what you want in almost all cases is simply decreasing the high end of the passband, keeping the low cut at 300Hz or so. SSB with a low cut of 600Hz sounds extremely bad. For the same reason, I find the XFIL button unsuitable in SSB mode since it wants to "center" the new filter which again causes the low cut to be way to high. I still think some of the design choices for this rig are not optimal for SSB operators. Knut - AB2TC Evert Bakker (PA2KW) wrote: > > Hello all, > > > > Today I received the 1.8 Kc 8 pole filter and installed it tonight. > > I did the configuration with the software tool used for firmware updates > as > well (also performed an update as well). > > All went OK, but I do have a feeling something is wrong or my ears/brains > work a little different from the majority (yeh yeh I know...) > > When XFil 2.7 is selected together with the DSP at 2.7 Kc, the audio > sounds > great. When decreasing the BW with the DSP to 1.8 (but keeping the centre > the same), the hardware filter is switched in at 1.8 Kc DSP setting. > During > the decreasing process I'm loosing "information" (Ofcourse!) but my > feeling > says too much. When during the decreasing process I also lower the centre > freq, the excessive loss of "information" is compensated. This gives me > the > feeling as if the filter isn't centered anymore. > > First I thought this might have to do something with the Offset (-0.91 for > a > 2.7 5 pole filter) but nothing was written on the 1.8 Kc 8 pole filter. I > just tried it, but that didn't compensate the excessive loss. > > > > During a process of decreasing bandwidth while listening to an SSB signal, > I > would appreciate if a shift of the centre-freq of the DSP is not required > > > > Any suggestion? > > > > 73's, Evert PA2KW > > > > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > > -- View this message in context: http://www.nabble.com/Xtal-Filters-tp17380222p17384263.html Sent from the Elecraft mailing list archive at Nabble.com. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by ab2tc
Hi Knut and all,
I totally agree with you. CW operation of the filters is fine. With SSB it would be way easier if the filter centre frequency would be reduced by a small amount as the width is reduced. In the "heat of battle" those small filter knobs are not easy to adjust without nudging the VFO (I don't have much feeling in my finger tips). I would prefer to use the XFIL button to immediately switch to a narrower filter which is suitably centered for SSB reception. With a 2.1KHz xtal filter the low frequency could be about 250Hz and 350Hz for a 1.8KHz filter. As this (XFIL button) seems to be the unused button on the K3 maybe one or two extra narrower filters for SSB could be setup in DSP with appropriate centering. This then would function even if you did not have the extra "roofing" filters. It would be way simpler than fiddling with those filter knobs. I always thought those knobs should have had a very positive detent (a 1/2 in. longer knob would help too). My shaky hands don't handle them well at all. Food for thought. 73 Tony Fegan VE3QF K3 #137 ab2tc wrote: > Hi, > > I am assuming that you are using SSB. For SSB, use the Hi Cut / Lo cut mode > instead and adjust the Hi Cut for lower bandwidth. The Shift / Width mode is > not suitable for SSB since it wants to keep the center frequency constant, > while what you want in almost all cases is simply decreasing the high end of > the passband, keeping the low cut at 300Hz or so. SSB with a low cut of > 600Hz sounds extremely bad. For the same reason, I find the XFIL button > unsuitable in SSB mode since it wants to "center" the new filter which again > causes the low cut to be way to high. I still think some of the design > choices for this rig are not optimal for SSB operators. > > Knut - AB2TC > > > Evert Bakker (PA2KW) wrote: > >> Hello all, >> >> >> >> Today I received the 1.8 Kc 8 pole filter and installed it tonight. >> >> I did the configuration with the software tool used for firmware updates >> as >> well (also performed an update as well). >> >> All went OK, but I do have a feeling something is wrong or my ears/brains >> work a little different from the majority (yeh yeh I know...) >> >> When XFil 2.7 is selected together with the DSP at 2.7 Kc, the audio >> sounds >> great. When decreasing the BW with the DSP to 1.8 (but keeping the centre >> the same), the hardware filter is switched in at 1.8 Kc DSP setting. >> During >> the decreasing process I'm loosing "information" (Ofcourse!) but my >> feeling >> says too much. When during the decreasing process I also lower the centre >> freq, the excessive loss of "information" is compensated. This gives me >> the >> feeling as if the filter isn't centered anymore. >> >> First I thought this might have to do something with the Offset (-0.91 for >> a >> 2.7 5 pole filter) but nothing was written on the 1.8 Kc 8 pole filter. I >> just tried it, but that didn't compensate the excessive loss. >> >> >> >> During a process of decreasing bandwidth while listening to an SSB signal, >> I >> would appreciate if a shift of the centre-freq of the DSP is not required >> >> >> >> Any suggestion? >> >> >> >> 73's, Evert PA2KW >> >> >> >> >> >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com >> >> >> > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Hi again,
I think your particular problem has a fairly simple solution. Press ("hold") the I/II button (on the HI/Width button) and set up the alternate 1.8kHz the way you want it. Now you will be able to switch between a wide and narrow SSB setting without twiddling any knobs. This is the way I do switch between "normal" and "contest" mode. But I still think the function of the XFIL button should be different in SSB mode. Knut - AB2TC
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In reply to this post by Evert Bakker (PA2KW)
Evert -
I haven't noticed that with mine. It just seems like a nice, linear reduction in bandwidth. I thought the sound of the 1.8 bandwidth was much nicer with the actual 1.8 filter + 1.8 DSP than the 2.8 filter + 1.8 DSP. 73, Steve NN4X On Wed, May 21, 2008 at 5:57 PM, Evert Bakker (PA2KW) <[hidden email]> wrote: > Hello all, > > > > Today I received the 1.8 Kc 8 pole filter and installed it tonight. > > I did the configuration with the software tool used for firmware updates as > well (also performed an update as well). > > All went OK, but I do have a feeling something is wrong or my ears/brains > work a little different from the majority (yeh yeh I know...) > > When XFil 2.7 is selected together with the DSP at 2.7 Kc, the audio sounds > great. When decreasing the BW with the DSP to 1.8 (but keeping the centre > the same), the hardware filter is switched in at 1.8 Kc DSP setting. During > the decreasing process I'm loosing "information" (Ofcourse!) but my feeling > says too much. When during the decreasing process I also lower the centre > freq, the excessive loss of "information" is compensated. This gives me the > feeling as if the filter isn't centered anymore. > > First I thought this might have to do something with the Offset (-0.91 for a > 2.7 5 pole filter) but nothing was written on the 1.8 Kc 8 pole filter. I > just tried it, but that didn't compensate the excessive loss. > > > > During a process of decreasing bandwidth while listening to an SSB signal, I > would appreciate if a shift of the centre-freq of the DSP is not required > > > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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