FLx GN Adding Db gain
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FLx GN I've bought a 400hz eight pole CW filter. Although the manual recommends 1-2 db for a setting, I see that the adjustment can be higher. What setting are most CW operator using? I can't tell that there is an improvement. Ted [hidden email]
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> I've bought a 400hz eight pole CW filter. Although the manual
> recommends 1-2 db for a setting, I see that the adjustment can be > higher. What setting are most CW operator using? You want to use the setting that most closely compensates for the filter's loss. If you lack a means of measurement, please use the recommended value. 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 wa6riv
There is a table of “first guess” filter gain
settings that Elecraft uses for factory-built units in the K3 Utility Help on
the Crystal Filter configuration page. The 400 Hz 8-pole filter has 7 dB
of gain in that table. After starting with these approximate values, you might measure
the AF voltage at the speaker, perhaps with the alternate VFO B display
function “AFV” described on page 36 of the owner’s manual to
display the AF voltage and set the filter gain settings so that the AF voltage
stays relatively constant as you change bandwidth when tuned to a steady
carrier (perhaps generated by a signal generator). You could also clip a
voltmeter across the speaker leads. Some just do this aurally. Dick, K6KR From:
[hidden email] [mailto:[hidden email]] On
Behalf Of wa6riv FLx GN I've
bought a 400hz eight pole CW filter. Although the manual recommends 1-2
db for a setting, I see that the adjustment can be higher. What setting are
most CW operator using? I can't tell that there is an improvement. Ted [hidden email] _______________________________________________ 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 wa6riv
<quote author="wa6riv"> FLx GN I've bought a 400hz eight pole CW filter. Although the manual recommends 1-2 db for a setting, I see that the adjustment can be higher. What setting are most CW operator using? <unquote> I measured the gain change going from 450 Hz to 400 HZ (where the rig changes from the 2.8 filter to the 400 Hz filter) by turning the AGC off and using WSJT v 4 signal power measurement function. I got 6-7 dB less signal through the narrow filter .. it was very obvious to my ear. Anyway, I found the menu option for filter gain and put in 6 dB for the narrow filter and 0 dB for the wider filter and now the transition across the 450- to 400 Hz bandwidth is very seamless. I am happy. The 2 dB number is bogus, in my opinion/experience. Ken
73
Ken |
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There is a table of starting values for each of the crystal filters in the
K3 Utility Help for the Filter Configuration page. Dick, K6KR -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Ken_ke2n Sent: Tuesday, November 11, 2008 7:23 AM To: [hidden email] Subject: Re: [K3] [Elecraft] FLx GN Adding Db gain FLx GN I've bought a 400hz eight pole CW filter. Although the manual recommends 1-2 db for a setting, I see that the adjustment can be higher. What setting are most CW operator using? <unquote> I measured the gain change going from 450 Hz to 400 HZ (where the rig changes from the 2.8 filter to the 400 Hz filter) by turning the AGC off and using WSJT v 4 signal power measurement function. I got 6-7 dB less signal through the narrow filter .. it was very obvious to my ear. Anyway, I found the menu option for filter gain and put in 6 dB for the narrow filter and 0 dB for the wider filter and now the transition across the 450- to 400 Hz bandwidth is very seamless. I am happy. The 2 dB number is bogus, in my opinion/experience. Ken -- View this message in context: http://n2.nabble.com/FLx-GN-Adding-Db-gain-tp1330201p1485455.html Sent from the [K3] 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 Ken_ke2n
> FLx GN
> > I've bought a 400hz eight pole CW filter. Although the manual recommends > 1-2 db for a setting, I see that the adjustment can be higher. What setting > are most CW operator using? > <unquote> > > I measured the gain change going from 450 Hz to 400 HZ (where the rig > changes from the 2.8 filter to the 400 Hz filter) by turning the AGC off and > using WSJT v 4 signal power measurement function. You can also use the AFV/dBV function in the radio to directly measure the filter insertion loss. I won't give you a step by step procedure. That is left as an exercise for you. I will suggest that AGC ought to be OFF, the signal you tune in ought to be steady with a good SNR, and that the K3 has an internal oscillator around 49.380 MHz. Enjoy! 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 wa6riv
hmmm let me try again
the value in the table for the 400 Hz filter is clearly wrong. or the spec for the filter has changed since the manunal was written Ken _______________________________________________ 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
73
Ken |
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Hmm - a conclusion is based on one data point? A compensation of 2dB
was correct in the case of my 400 Hz filter - but that's just anecdotal too. Bob NW8L On Tue, Nov 11, 2008 at 8:40 AM, <[hidden email]> wrote: > hmmm let me try again > > the value in the table for the 400 Hz filter is clearly wrong. > or the spec for the filter has changed since the manunal was written > > Ken > > _______________________________________________ > 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 Ken_ke2n
Hi Ken,
> The 2 dB number is bogus, in my opinion/experience. At least for me the 2dB recommendation for the 400Hz hit the nail right on the head. But on the other hand, I am not much of CW man. vy 73 de toby -- DD5FZ (ex 4n6fz, dj7mgq, dg5mgq, dd5fz) K2 #885, K2/100 #3248, K3 #67 _______________________________________________ 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've looked at three 400 Hz filters to date and values do vary from
filter to filter; one of mine required 6 dB gain. Other 8-pole filter bandwidths also vary a bit as well. Just measure all the filters in the radio and true up the gains. Don't need to worry about what the actually gain numbers are, as long as they can be goosed up to a uniform level. on 08 Nov 11 Tue 10:44 [hidden email] said the following: > Hi Ken, > >> The 2 dB number is bogus, in my opinion/experience. > > At least for me the 2dB recommendation for the 400Hz hit the nail > right on the head. But on the other hand, I am not much of CW man. > > vy 73 de toby _______________________________________________ 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 wa6riv
K3NA wrote:
"I've looked at three 400 Hz filters
to date and values do vary from
filter to filter; one of mine required 6 dB gain. Other 8-pole filter bandwidths also vary a bit as well. Just measure all the filters in the radio and true up the gains. Don't need to worry about what the actually gain numbers are, as long as they can be goosed up to a uniform level." I have the 500 Hz 5-pole, 400 Hz 8-pole, and 200 Hz 5-pole
filters
and "trued up" the gains by ear and came up with 2dB, 6dB, and
8 DB respectively. This ability to adjust the gain in
one dB
increments to compensate for filter insertion loss is a
wonderful
feature of the K3. BTW, the 400 Hz 8-pole is my favorite
CW
filter.
73,
Chuck Guenther NI0C
K2/10 s/n 5853
K3/100 s/n 1061
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Thanks to all who responded to this
thread. I have K3 1433 with 2.8K and 400 Hz. filters. I boosted the 400 gain
from 2 to 6 and the difference was amazing. With the NR the CW is now EASILY cleaned
up at VERY narrow bandwidths! I thought it was good before but now I see why
contesters and DXers would love this rig. Jack, AE6GC K3NA wrote: "I've looked at three 400 Hz filters to date and values do vary from I have the 500 Hz 5-pole, 400 Hz 8-pole, and 200 Hz 5-pole
filters and "trued up" the gains by ear and came up with
2dB, 6dB, and 8 DB respectively. This ability to adjust the gain in
one dB increments to compensate for filter insertion loss is a
wonderful feature of the K3. BTW, the 400 Hz 8-pole is my
favorite CW filter. 73, Chuck Guenther NI0C K2/10 s/n 5853 K3/100 s/n 1061
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In reply to this post by Ken_ke2n
The value in the table in the K3 Utility Help for the Crystal Filter
Configuration for the 400 Hz filter is 7 dB. This is a starting point. Your individual filter may vary from that. The values in this table came from the Elecraft manufacturing lab. These are the starting gain compensation values that Elecraft uses when it prepares a factory-built K3. After these starting values are set, then the filter gain compensation is further adjusted (using a voltmeter across the speaker and a signal generator, I think) to deal with filter sample variations. 7 db from the table in K3 Utility Help seems pretty close to the 6-7 db you mentioned in your findings. I agree that the value in the Owner's Manual isn't consistent with this. Dick, K6KR -----Original Message----- From: [hidden email] [mailto:[hidden email]] Sent: Tuesday, November 11, 2008 7:40 AM To: "Dick Dievendorff"; [hidden email] Subject: RE: [K3] [Elecraft] FLx GN Adding Db gain hmmm let me try again the value in the table for the 400 Hz filter is clearly wrong. or the spec for the filter has changed since the manunal was written Ken _______________________________________________ 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 wa6riv
>What setting
>are most CW operator using? Here are my K3 filter gain settings that make for mostly seamless transitions. I did this by ear and looking at AFV. 13 KHz +1 dB 6 KHz +2 dB 2.7 KHz 0 dB 0.5 KHz +6 dB So I agree that the narrower filters seem to need more than 2 dB gain adjustment. The wider filter gain adjustments above are probably normal filter variations within a lot, possibly because my 2.7 KHz filter has maybe a dB less than average loss Mike Scott - AE6WA Tarzana, CA (DM04 / near LA) K3-100 #508/ KX1 #1311 _______________________________________________ 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 wa6riv
>There is a table of starting values for each of the crystal filters in the
>K3 Utility Help for the Filter Configuration page. >Dick, K6KR Dick I notice that the table from K3 Utility Help (snippet below) does not show the stock 2.7 KHz filter. I would guess 0 dB but strange that it wasn't included. Part Number Bandwidth Gain KFL3A-200 0.20 kHz 8 dB KFL3A-250 0.25 kHz 8 dB KFL3A-400 0.40 kHz 7 dB KFL3A-500 0.50 kHz 6 db KFL3A-1.0K 1.00 kHz 1 dB KFL3A-1.8K 1.80 kHz 2 dB KFL3A-2.1K 2.10 kHz 2 dB KFL3A-2.8K 2.80 kHz 0 dB KFL3A-6K 6.00 kHz 0 dB KFL3B-FM 13.00 kHz 0 dB Mike Scott - AE6WA Tarzana, CA (DM04 / near LA) K3-100 #508/ KX1 #1311 _______________________________________________ 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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This has been corrected in a version of the K3 Utility that is now being
evaluated by Field Test. 0 db is right. Thanks! Dick -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Mike Scott Sent: Tuesday, November 11, 2008 12:40 PM To: [hidden email] Subject: RE: [K3] [Elecraft] FLx GN Adding Db gain >There is a table of starting values for each of the crystal filters in the >K3 Utility Help for the Filter Configuration page. >Dick, K6KR Dick I notice that the table from K3 Utility Help (snippet below) does not show the stock 2.7 KHz filter. I would guess 0 dB but strange that it wasn't included. Part Number Bandwidth Gain KFL3A-200 0.20 kHz 8 dB KFL3A-250 0.25 kHz 8 dB KFL3A-400 0.40 kHz 7 dB KFL3A-500 0.50 kHz 6 db KFL3A-1.0K 1.00 kHz 1 dB KFL3A-1.8K 1.80 kHz 2 dB KFL3A-2.1K 2.10 kHz 2 dB KFL3A-2.8K 2.80 kHz 0 dB KFL3A-6K 6.00 kHz 0 dB KFL3B-FM 13.00 kHz 0 dB Mike Scott - AE6WA Tarzana, CA (DM04 / near LA) K3-100 #508/ KX1 #1311 _______________________________________________ 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 |
dB Gain -- was RE: FLx GN Adding Db gain
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In reply to this post by Dick Dievendorff
At the risk of being pedantic, the correct unit is the deciBel, one
tenth of a Bel, and the correct abbreviation is dB (not Db). The Bel is a unit of change in loudness and is named after Alexander Graham Bell. Because the way humans hear is logarithmic (as is our perception of light), the Bel (and the deciBel) are the log of the ratio of sound levels, and are translated into the log of power levels and voltage levels corresponding to that loudness change. 73, Jim K9YC _______________________________________________ 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 |
RE: dB Gain -- was RE: FLx GN Adding Db gain
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Lots of questions. See some answers interspersed.
On Tue, 11 Nov 2008 18:22:50 -0800, Dick Dievendorff wrote: >I think I usually get that right (along with kHz), but I get confused when I >see dBi, dBm, seemingly dBx for all X. I presume it's a measure of loudness >relative to X, so a dBi is gain relative to an isotropic radiator, and dBw >is what with watts? All dB is relative -- that is, A is x dB louder or quieter than B. >And is a dB of voltage equivalent to a dB of power or an audio dB of >loudness? The equation for ALL dB numbers is dB = 20 log (V1/V2) or 10 log (P1/P2), where V is voltage and P is power. When you append a letter to it, the letter defines some reference condition that could be voltage, power in some impedance, acoustic loudness, etc. MANY references have been defined. dBm indicates dB referenced to 1 mW. dBmV is dB referenced to 1 mV. dBu indicates a reference to 0.78V dBV is referenced to 1 volt. What is a VU meter measuring? Voltage? It's actually measuring power if it's a true VU meter. 0VU is 1 mW in 600 ohms, and a VU meter has a carefully defined dynamic characteristic -- that is, the meter movement has its ballistic characteristics defined so that it indicates subjective loudness -- sort of. The standard for the VU meter goes back to the early days of broadcasting. VERY few modern meters calibrated in VU actually have this characteristic, which isn't cheap to build. AND -- most VU meters are calibrated so that a reading of 0 dB is +4VU or +8VU. Not only that, but a true VU meter includes rectifiers that combine with the ballistics to do a lot of smoothing so that they are reading the average power. Actual peaks of audio are typically 10-14 dB hotter than the indicated reading. Are you confused yet? :) >And why are our ears logarithmic anyway? That's the way God made us. >And every time I see a recording studio meter in a movie or TV clip, it's >seemingly always dancing to the pin, way over into the red. Why do they do >that? Broadcasters have long been in an eternal search for loudness. If the meter moves below the red there isn't enough processing, and someone is going to get fired. :) What does the red mean? In today's world, not much, because broadcast stations, like hams, use LOTS of signal processing -- compression, peak limiting, and other tricks -- that prevent those peaks from being much greater than the average voltage. If there were no processing, the red range of the meter would indicate that the waveform was getting close to clipping on peaks. 73, Jim K9YC _______________________________________________ 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 |
Re: dB Gain -- was RE: FLx GN Adding Db gain
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Jim Brown wrote:
> Lots of questions. See some answers interspersed. > > On Tue, 11 Nov 2008 18:22:50 -0800, Dick Dievendorff wrote: > >> I think I usually get that right (along with kHz), but I get confused when I >> see dBi, dBm, seemingly dBx for all X. I presume it's a measure of loudness >> relative to X, so a dBi is gain relative to an isotropic radiator, and dBw >> is what with watts? > > All dB is relative -- that is, A is x dB louder or quieter than B. Unfortunately, on the K3, Elecraft apparently confuse the issue by using a "v" suffix to indicate that the dB, although not relative to a defined standard, are computed using the 20 Log 10 (V1/V2) method, rather rather than the 10 Log 10 (P1/P2) method. (Whilst these are identical if the load impedance is constant, they produce different results if the impedance isn't constant.) > >> And is a dB of voltage equivalent to a dB of power or an audio dB of >> loudness? Audio dB are weighted by frequency, so the same power at different frequencies will not produce a 0dB difference. > > Broadcasters have long been in an eternal search for loudness. If the meter > moves below the red there isn't enough processing, and someone is going to > get fired. :) It's more complex than that. Classical music broadcasters need to respect dynamic range, whereas pop music broadcasters tend to want maximum loudness. FM broadcasts tend to be companded less than AM ones. In the UK, at least, TV adverts are transmitted at a higher loudness than most programme material. -- David Woolley "The Elecraft list is a forum for the discussion of topics related to Elecraft products and more general topics related ham radio" List Guidelines <http://www.elecraft.com/elecraft_list_guidelines.htm> _______________________________________________ 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 |
Re: dB Gain -- was RE: FLx GN Adding Db gain
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On Thu, 13 Nov 2008 23:42:37 +0000, David Woolley (E.L) wrote:
>Audio dB are weighted by frequency, so the same power at different >frequencies will not produce a 0dB difference. The use of weighting requires another suffix. >It's more complex than that. Classical music broadcasters need to >respect dynamic range Of course -- I oversimplified (only slightly) as an exageration of conditions in the US. Here we have VERY few classical broadcasters. AND -- while dynamic range must be respected, it cannot be maintained as a copy of an actual performance because the noise level of the listening environment is simply too high. A symphonic performance on CD can have a dynamic range of 90 dB, but the noise level in most homes is on the order of 50 dBA. 90 dB + 50 dBA = 140 dBA, which is 20 dB more than almost any home stereo rig. And your car is more like 70 dBA. 73, Jim K9YC _______________________________________________ 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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