K3 dbV in 2.38
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When turning on the K3, the dbV readout (AGC off) reads +99.9. Tech menu is on and other parameters one can display are OK.
It doesn't change until I get impatient and start tuning around, turning menu main on/off or switching between parameters with the VFO B knob. It is not clear what brings it to life. ( A two minute wait alone does not do it.) After that it works properly. Anybody else seeing this? 73 de Brian/K3KO |
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Brian,
You have to let the AFV value stabilize first, and then the dBV shows the value compared to the last AFV value. Page 36 of the manual shows more details. 73 's Steef PA2A K3 1184 ----- Original Message ----- From: "alsopb" <[hidden email]> To: <[hidden email]> Sent: Tuesday, September 16, 2008 2:47 PM Subject: [Elecraft] K3 dbV in 2.38 > > When turning on the K3, the dbV readout (AGC off) reads +99.9. Tech menu > is > on and other parameters one can display are OK. > > It doesn't change until I get impatient and start tuning around, turning > menu main on/off or switching between parameters with the VFO B knob. It > is > not clear what brings it to life. ( A two minute wait alone does not do > it.) > After that it works properly. > > Anybody else seeing this? > > 73 de Brian/K3KO > > > -- > View this message in context: > http://n2.nabble.com/K3-dbV-in-2.38-tp1092599p1092599.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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Hi Steff,
Thanks reply. Try this. Set your K3 up to display dBV. Turn your K3 off. Turn the K3 on. Look at the value. Wait. See if it ever changes from +99.9. It never does here. This works: Have any other parameter displayed in the VFO B area. Turn rig off. Turn it on. That parameter does display. Then turn VFO B to display dbV. In a matter of seconds, it displays OK. It is like the K3 doesn't know the dBV display option has been selected at startup-- at least here. No big problem of course. 73 de Brian/K3KO
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> Try this. Set your K3 up to display dBV. Turn your K3 off. > Turn the K3 on. Look at the value. Wait. See if it ever > changes from +99.9. It never does here. In setting up the dBV display, you must first set a reference. Select AFV (AF Voltage), allow the display to stabilize, then select dBV. If dBV is selected when initially applying power to the K3, the reference voltage is ALWAYS zero volts. ANY audio output is an infinite increase over zero - thus 99.9 dBV. As Stef says, you must first set a reference (AFV) before the dBV (relative change) value has any meaning. > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]] On Behalf Of alsopb > Sent: Tuesday, September 16, 2008 4:50 PM > To: [hidden email] > Subject: Re: [Elecraft] K3 dbV in 2.38 > > > > Hi Steff, > > Thanks reply. > > Try this. Set your K3 up to display dBV. Turn your K3 off. > Turn the K3 on. Look at the value. Wait. See if it ever > changes from +99.9. It never does here. > > This works: > Have any other parameter displayed in the VFO B area. Turn > rig off. Turn it on. That parameter does display. Then turn > VFO B to display dbV. In a matter of seconds, it displays OK. > > It is like the K3 doesn't know the dBV display option has > been selected at > startup-- at least here. > > No big problem of course. > > 73 de Brian/K3KO > > > > Steef PA2A wrote: > > > > Brian, > > > > You have to let the AFV value stabilize first, and then the > dBV shows > > the value compared to the last AFV value. Page 36 of the > manual shows > > more details. > > > > 73 's Steef PA2A > > K3 1184 > > > > ----- Original Message ----- > > From: "alsopb" <[hidden email]> > > To: <[hidden email]> > > Sent: Tuesday, September 16, 2008 2:47 PM > > Subject: [Elecraft] K3 dbV in 2.38 > > > > > >> > >> When turning on the K3, the dbV readout (AGC off) reads > +99.9. Tech > >> menu > >> is > >> on and other parameters one can display are OK. > >> > >> It doesn't change until I get impatient and start tuning around, > >> turning menu main on/off or switching between parameters > with the VFO > >> B knob. It is not clear what brings it to life. ( A two > minute wait > >> alone does not do > >> it.) > >> After that it works properly. > >> > >> Anybody else seeing this? > >> > >> 73 de Brian/K3KO > >> > >> > >> -- > >> View this message in context: > >> http://n2.nabble.com/K3-dbV-in-2.38-tp1092599p1092599.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 > > > > > > -- > View this message in context: > http://n2.nabble.com/K3-dbV-in-2.38-tp1092599p1093680.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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On Tue, 16 Sep 2008 17:29:46 -0400, Joe Subich, W4TV wrote:
>As Stef says, you must first set a reference (AFV) before the >dBV (relative change) value has any meaning. That MAY be how it's programmed, but that would not be right. 0 dBV is quite well defined by international standard as 1 volt RMS. 0 dBu is defined as 0.78 volts. Both of these are purely voltage measurements, independent of impedance. 0 dBm is 1 mw -- to measure it, one must also know the impedance. 0 dBu is the voltage that would be present with 0 dBm in 600 ohms. 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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The K3's dBV function is a *relative* measure. It must be set to
whatever reference you wish by first using AFV. The calculation measurement is true RMS. It is used for measuring things like MDS, AGC slope, roofing filter attenuation and so forth. This function has been in the K3 for a very long time (as K3 things go) and has always worked in exactly this manner. 73, Lyl eKK7P _______________________________________________ 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 Jim Brown-10
Maybe dBv stands for dB "variable," not dB with respect to a volt.
Once you get used to it, the relative reference can be of some benefit. For example, set dBV to 0.0 at the bandwith peak and then the dBV reading gives you a direct reference to how many dB down from the filter peak you are when doing a filter bandwidth scan. Jack K8ZOA Jim Brown wrote: > On Tue, 16 Sep 2008 17:29:46 -0400, Joe Subich, W4TV wrote: > > >> As Stef says, you must first set a reference (AFV) before the >> dBV (relative change) value has any meaning. >> > > That MAY be how it's programmed, but that would not be right. 0 dBV > is quite well defined by international standard as 1 volt RMS. 0 dBu > is defined as 0.78 volts. Both of these are purely voltage > measurements, independent of impedance. 0 dBm is 1 mw -- to measure > it, one must also know the impedance. 0 dBu is the voltage that > would be present with 0 dBm in 600 ohms. > > 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 > > 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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> Maybe dBv stands for dB "variable," not dB with respect to a volt.
Not with respect one volt, but voltage based, using the 20log rather than the power-based 10log conversion. AFV is "AF Voltage" and corresponds to the voltage you would measure across the speaker with AF GAIN set to max. Units are mV RMS, and over-range truncates the MSD in the display (but is still accurate, I think, over the serial port). I no longer remember if this is with AF gain scaling set to H or L. 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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On Tue, 16 Sep 2008 15:40:04 -0700, Lyle Johnson wrote:
>> Maybe dBv stands for dB "variable," not dB with respect to a volt. >Not with respect one volt, but voltage based, using the 20log rather >than the power-based 10log conversion. Hold on a minute. We cannot sit over in our little corner and pretend that the rest of the world does not exist. That's how we got into trouble with the KIO3. dBV is a voltage measure with a reference of 1V RMS. It's an international standard. If a K3 function does something else, it needs to be called something else. 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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Jim Brown wrote:
> ... > Hold on a minute. We cannot sit over in our little corner and pretend > that the rest of the world does not exist. That's how we got into > trouble with the KIO3. > > dBV is a voltage measure with a reference of 1V RMS. It's an > international standard. If a K3 function does something else, it needs > to be called something else. Agreed. If dBr is not already taken how about using it to mean "dB relative"? My searches have turned up no conflicts for this designation as it relates to voltage measurements. Gus Hansen KB0YH _______________________________________________ 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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On Sep 16, 2008, at 5:07 PM, Augie Hansen wrote: > Jim Brown wrote: >> ... >> Hold on a minute. We cannot sit over in our little corner and >> pretend that the rest of the world does not exist. That's how we >> got into trouble with the KIO3. >> dBV is a voltage measure with a reference of 1V RMS. It's an >> international standard. If a K3 function does something else, it >> needs to be called something else. > > Agreed. If dBr is not already taken how about using it to mean "dB > relative"? My searches have turned up no conflicts for this > designation as it relates to voltage measurements. I agree with both of you. However, just a small nit... dB (decibel) is already a relative measure, with no units. When another letter is appended, it turns the value to an absolute measure (m for miiliwatts, V for 1 V RMS, u for 0.775 V RMS, etc). If you use dBr, you'll need to define what unit "r" is in. I.e., dBr is no longer just a ratio, but a value that is relative to 1 "r". 73 Chen, W7AY _______________________________________________ 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 Jim Brown-10
I suppose when Wayne has time, he can modify the display driver to light two fewer segments so the "V" is "v." That will not conflict with dBV is that offends your sense of propriety. However, since the previous "meter selection" is AFV (AF Voltage), dBV makes plenty of sense as way to identify the meter setting. dBA would also make sense but it also has a specific "standard" meaning. > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]] On Behalf Of Jim Brown > Sent: Tuesday, September 16, 2008 7:54 PM > To: [hidden email] > Subject: Re: [Elecraft] K3 dbV in 2.38 > > > On Tue, 16 Sep 2008 15:40:04 -0700, Lyle Johnson wrote: > > >> Maybe dBv stands for dB "variable," not dB with respect to a volt. > > >Not with respect one volt, but voltage based, using the 20log rather > >than the power-based 10log conversion. > > Hold on a minute. We cannot sit over in our little corner and pretend > that the rest of the world does not exist. That's how we got into > trouble with the KIO3. > > dBV is a voltage measure with a reference of 1V RMS. It's an > international standard. If a K3 function does something else, > it needs > to be called something else. > > 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 _______________________________________________ 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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On Sep 16, 2008, at 5:38 PM, Joe Subich, W4TV wrote: > I suppose when Wayne has time, he can modify the display > driver to light two fewer segments so the "V" is "v." That is probably no good either. dBv is the deprecated version of dBu. It was changed from dBv to dBu because it was too easy to confuse dBv with dBV. If you reference to a full scale meter reading or A/D converter clipping level, a standard that is in use is dBFS (or dBfs). 73 Chen, W7AY _______________________________________________ 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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> If you reference to a full scale meter reading or A/D converter clipping
> level, a standard that is in use is dBFS (or dBfs). We have a total of three characters available, and we wanted to express that this was a dB value, and it was voltage based. So we used dBV. 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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Lyle Johnson wrote:
> > We have a total of three characters available, and we wanted to express > that this was a dB value, and it was voltage based. So we used dBV. Into a linear load, and I presume we have one here[A], there is no difference between dB relative to a voltage, using the 20 log10, voltage, formula and dB relative to the power corresponding to that voltage using the 10 log10. power, formula. The difference between 10 and 20 is to account for the need to square the voltage to get the power. In this case the units should be bare dB. You will still have problems because of the large number of people who don't know the definition of a dB and are only used to seeing dB's relative to some defined standard. [A] strictly speaking the load at any one stage could be non-linear, as long as the total system, through to the air outside the speaker believes in a linear way. -- 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: K3 dbV in 2.38
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In reply to this post by alsopb
Would it be useful to call it Vdb, i.e. a voltage measurement not
necessarily using the 1V RMS standard reference? 73, Geoff GM4ESD > On Tue, 16 Sep 2008 15:40:04 -0700, Lyle Johnson wrote: > >>> Maybe dBv stands for dB "variable," not dB with respect to a volt. > >>Not with respect one volt, but voltage based, using the 20log rather >>than the power-based 10log conversion. Jim K9YC wrote: > Hold on a minute. We cannot sit over in our little corner and pretend > that the rest of the world does not exist. That's how we got into > trouble with the KIO3. > > dBV is a voltage measure with a reference of 1V RMS. It's an > international standard. If a K3 function does something else, it needs > to be called something else. _______________________________________________ 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 alsopb
Lateral thinking. Sounds good to me
David G3UNA > > From: "Geoffrey Mackenzie-Kennedy" <[hidden email]> > Date: 2008/09/17 Wed AM 09:33:31 BST > To: "Elecraft Discussion List" <[hidden email]> > Subject: Re: [Elecraft] K3 dbV in 2.38 > > Would it be useful to call it Vdb, i.e. a voltage measurement not > necessarily using the 1V RMS standard reference? > > 73, > Geoff > GM4ESD > > > > On Tue, 16 Sep 2008 15:40:04 -0700, Lyle Johnson wrote: > > > >>> Maybe dBv stands for dB "variable," not dB with respect to a volt. > > > >>Not with respect one volt, but voltage based, using the 20log rather > >>than the power-based 10log conversion. > > Jim K9YC wrote: > > > Hold on a minute. We cannot sit over in our little corner and pretend > > that the rest of the world does not exist. That's how we got into > > trouble with the KIO3. > > > > dBV is a voltage measure with a reference of 1V RMS. It's an > > international standard. If a K3 function does something else, it needs > > to be called something else. > > _______________________________________________ > 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 > ----------------------------------------- Email sent from www.virginmedia.com/email Virus-checked using McAfee(R) Software and scanned for spam _______________________________________________ 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 KK7P
On 2008-09-17 00.26, "Lyle Johnson" <[hidden email]> wrote:
> The K3's dBV function is a *relative* measure. It must be set to > whatever reference you wish by first using AFV. The calculation > measurement is true RMS. It is used for measuring things like MDS, AGC > slope, roofing filter attenuation and so forth. So what's the correct procedure for measuring MDS using the internal meter and a XG2 oscillator? 73 de Björn /SM0MDG _______________________________________________ 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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>> The K3's dBV function is a *relative* measure. It must be set to
>> whatever reference you wish by first using AFV. The calculation >> measurement is true RMS. It is used for measuring things like MDS, AGC >> slope, roofing filter attenuation and so forth. > > So what's the correct procedure for measuring MDS using the internal meter > and a XG2 oscillator? See the MDS procedure in the XG2 manual, pages 5-7. You can use the K3 AFV and/or dBV functions instead of an external meter. 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 Bjorn
You should be able to use the AFV readings instead of the voltage
measured with a DMM across the speaker - then using those values, enter them into the calculations in the XG2 manual for calculating MDS. 73, Don W3FPR Björn Mohr wrote: > On 2008-09-17 00.26, "Lyle Johnson" <[hidden email]> wrote: > > >> The K3's dBV function is a *relative* measure. It must be set to >> whatever reference you wish by first using AFV. The calculation >> measurement is true RMS. It is used for measuring things like MDS, AGC >> slope, roofing filter attenuation and so forth. >> > > So what's the correct procedure for measuring MDS using the internal meter > and a XG2 oscillator? > > 73 de Björn /SM0MDG > > > > > _______________________________________________ > 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 > ------------------------------------------------------------------------ > > > No virus found in this incoming message. > Checked by AVG - http://www.avg.com > Version: 8.0.169 / Virus Database: 270.6.21/1676 - Release Date: 9/17/2008 9:33 AM > > 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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