It have to work better!
Locked
It have to work better!
 
|
Hi for all K3-users,
Some weeks we searched for the reason of bad K3's sound and high level IMD. We tried to replace resistors on the "line-out board". But it is ineffectual. Fortunately, Vlad UN7GZ has found out the problem. Vlad has analysed the K3-scheme and has found some discrepancy on the RF-board. This problem in poor-quality assembly. I also have made necessary corrections on my K3. The result are impressing! Now I hear the sound is much more better (like my K2). You can see all of these results: here is plot BEFORE "modification" (you can see terrible "spur" near 12kHz) http://forum.cqham.ru/download.php?id=32620 here is plots AFTER "modification": http://forum.cqham.ru/download.php?id=32621 http://forum.cqham.ru/download.php?id=32651 http://forum.cqham.ru/download.php?id=32650 And of course you can read about it here in Russian: http://forum.cqham.ru/viewtopic.php?t=17137 All these results is equal for ALL of K3-outs (both phones-outs and line-out). 73! Alex UR5LAM RU-QRP-Club#0103 K3/100F #0568 _______________________________________________ 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: It have to work better!
|
Hi Alex,
What is the mod/problem found?? 73, Julius n2wn
Julius Fazekas
N2WN Tennessee Contest Group http://www.k4ro.net/tcg/index.html Tennessee QSO Party http://www.tnqp.org/ Elecraft K2 #4455 Elecraft K3/100 #366 Elecraft K3/100 |
|
|
Yes Alex, can you please say more about what you found on the RF Board and what the fix was? Congratulations on the success! 73, Barry N1EU |
|
|
In reply to this post by Alexander Ponomarenko-5
Priwet Alex! I believe you are referring to this picture posted by UN7GZ: http://forum.cqham.ru/download.php?id=32295 Was this W16 jumper cable completely missing or was it just poorly soldered? I also noticed some references on the list about the KXV3 RX ANT isolation problem. I assume you know this is covered on the K3 Enhancements and Application Notes page under "Receive Antenna TX Isolation Improvement (RXA Mod Kit for the KXV3)". This mod is not required for units with the KXV3 "Rev B" Main Board. http://www.elecraft.com/K3/k3_app_notes.htm 73, Bill W4ZV |
Re: It have to work better!
|
|
Priwet Bill,
In original K3 the W16 is monowire (on top of the RF-board), but if we will analyze the scheme, we can see that W16 must be in the screen. The W16 are near non screen-shielded BP-Filters, and we can see second RX-channel on my first web-link: http://forum.cqham.ru/download.php?id=32620 You can get out monowire W16, and replace to new W16 (behind RF-board in our opinion). You must to use coaxial-cable for W16. I'm used silver-plated screen-shielded video-cable from Supra. 73! Alex UR5LAM Bill W4ZV wrote: > Priwet Alex! > > I believe you are referring to this picture posted by UN7GZ: > > http://forum.cqham.ru/download.php?id=32295 > > Was this W16 jumper cable completely missing or was it just poorly soldered? > > I also noticed some references on the list about the KXV3 RX ANT isolation > problem. I assume you know this is covered on the K3 Enhancements and > Application Notes page under "Receive Antenna TX Isolation Improvement (RXA > Mod Kit for the KXV3)". This mod is not required for units with the KXV3 > "Rev B" Main Board. > > http://www.elecraft.com/K3/k3_app_notes.htm > > 73, Bill W4ZV 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 |
|
|
Yes, that seems correct Alex. The K3 schematic clearly shows that W16 is supposed to include a grounded shield. 73, Barry N1EU |
|
|
Hi,
My spectrum on the line out isn't even as clean as the "before" picture. In addition to the spur at 12kHz I have spurs at 3.9kHz and 7.8kHz. They, as well as the 12kHz spur are down about 75dB relative to an above AGC threshold single tone. They are independent of mode and passband settings. I doubt if they are audible (I can't hear them), but if a simple replacement of a jumper could fix it, I would be willing to look at it. Where is W16? On the picture in Fig. 14 in the assembly manual I can clearly see W15, W17, W18, all unshielded wire jumpers, but not W16. Knut - AB2TC
|
|
|
In reply to this post by Alexander Ponomarenko-5
It is the green colored wire beneath the noise blanker board?
And you replaced it with a coaxial cable on the bottom side of the RF board, is that right? 73, Drew AF2Z On Mon, 24 Nov 2008 19:25:56 +0200, Alex UR5LAM wrote: >Priwet Bill, > >In original K3 the W16 is monowire (on top of the RF-board), >but if we will analyze the scheme, we can see that W16 must be in the >screen. >The W16 are near non screen-shielded BP-Filters, and we can see second >RX-channel on my first web-link: >http://forum.cqham.ru/download.php?id=32620 >You can get out monowire W16, and replace to new W16 (behind RF-board in >our opinion). >You must to use coaxial-cable for W16. I'm used silver-plated >screen-shielded video-cable from Supra. > >73! Alex UR5LAM > _______________________________________________ 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: It have to work better!
|
|
In reply to this post by Barry N1EU
Barry N1EU wrote:
> > > Alexander Ponomarenko-5 wrote: >> In original K3 the W16 is monowire (on top of the RF-board), >> but if we will analyze the scheme, we can see that W16 must be in the >> screen. >> The W16 are near non screen-shielded BP-Filters, and we can see second >> RX-channel on my first web-link: >> http://forum.cqham.ru/download.php?id=32620 >> You can get out monowire W16, and replace to new W16 (behind RF-board in >> our opinion). >> You must to use coaxial-cable for W16. I'm used silver-plated >> screen-shielded video-cable from Supra. >> > Yes, that seems correct Alex. > > The K3 schematic clearly shows that W16 is supposed to include a grounded > shield. > > 73, > Barry N1EU > No Barry, that seems as defective. Can be Chinese assembly is guilty? :) 73! Alex UR5LAM _______________________________________________ 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: It have to work better!
|
|
In reply to this post by drewko
Yes Drew,
it is right. And it is only beginning (W16). 73! Alex UR5LAM drewko wrote: > It is the green colored wire beneath the noise blanker board? > > And you replaced it with a coaxial cable on the bottom side of the RF > board, is that right? > > 73, > Drew > AF2Z > > > On Mon, 24 Nov 2008 19:25:56 +0200, Alex UR5LAM wrote: > >> Priwet Bill, >> >> In original K3 the W16 is monowire (on top of the RF-board), >> but if we will analyze the scheme, we can see that W16 must be in the >> screen. >> The W16 are near non screen-shielded BP-Filters, and we can see second >> RX-channel on my first web-link: >> http://forum.cqham.ru/download.php?id=32620 >> You can get out monowire W16, and replace to new W16 (behind RF-board in >> our opinion). >> You must to use coaxial-cable for W16. I'm used silver-plated >> screen-shielded video-cable from Supra. >> >> 73! Alex UR5LAM 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: It have to work better!
|
|
In reply to this post by Alexander Ponomarenko-5
Hi Alex,
are the both ends of coax shield soldered to GND ? thanks for info, Lexa, OK1DST K3/10 #727 Alexander Ponomarenko napsal(a): > Barry N1EU wrote: >> >> >> Alexander Ponomarenko-5 wrote: >>> In original K3 the W16 is monowire (on top of the RF-board), >>> but if we will analyze the scheme, we can see that W16 must be in the >>> screen. >>> The W16 are near non screen-shielded BP-Filters, and we can see >>> second RX-channel on my first web-link: >>> http://forum.cqham.ru/download.php?id=32620 >>> You can get out monowire W16, and replace to new W16 (behind RF-board >>> in our opinion). >>> You must to use coaxial-cable for W16. I'm used silver-plated >>> screen-shielded video-cable from Supra. >>> >> Yes, that seems correct Alex. >> >> The K3 schematic clearly shows that W16 is supposed to include a grounded >> shield. >> 73, >> Barry N1EU >> > > No Barry, that seems as defective. > Can be Chinese assembly is guilty? :) > > 73! Alex UR5LAM > _______________________________________________ > 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 |
Re: It have to work better!
|
Administrator
|
In reply to this post by Barry N1EU
The schematic is in error. It was found that the coax was unnecessary.
The levels of signals reported are not audible at greater than 50-60 dB down from normal signals and do not impact our sensitivity spec. 73, Eric WA6HHQ ---- Barry N1EU wrote: > Alexander Ponomarenko-5 wrote: > >> In original K3 the W16 is monowire (on top of the RF-board), >> but if we will analyze the scheme, we can see that W16 must be in the >> screen. >> The W16 are near non screen-shielded BP-Filters, and we can see second >> RX-channel on my first web-link: >> http://forum.cqham.ru/download.php?id=32620 >> You can get out monowire W16, and replace to new W16 (behind RF-board in >> our opinion). >> You must to use coaxial-cable for W16. I'm used silver-plated >> screen-shielded video-cable from Supra. >> >> > Yes, that seems correct Alex. > > The K3 schematic clearly shows that W16 is supposed to include a grounded > shield. > > 73, > Barry N1EU > > 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: It have to work better!
|
|
In reply to this post by Alexandr Kobranov
Hi Lexa,
yes both, it's right: http://forum.cqham.ru/download.php?id=32786 73! Alex UR5LAM Alexandr Kobranov wrote: > Hi Alex, > > are the both ends of coax shield soldered to GND ? > > thanks for info, > > Lexa, OK1DST > K3/10 #727 > > Alexander Ponomarenko napsal(a): >> Barry N1EU wrote: >>> >>> >>> Alexander Ponomarenko-5 wrote: >>>> In original K3 the W16 is monowire (on top of the RF-board), >>>> but if we will analyze the scheme, we can see that W16 must be in >>>> the screen. >>>> The W16 are near non screen-shielded BP-Filters, and we can see >>>> second RX-channel on my first web-link: >>>> http://forum.cqham.ru/download.php?id=32620 >>>> You can get out monowire W16, and replace to new W16 (behind >>>> RF-board in our opinion). >>>> You must to use coaxial-cable for W16. I'm used silver-plated >>>> screen-shielded video-cable from Supra. >>>> >>> Yes, that seems correct Alex. >>> >>> The K3 schematic clearly shows that W16 is supposed to include a >>> grounded >>> shield. 73, >>> Barry N1EU >>> >> >> No Barry, that seems as defective. >> Can be Chinese assembly is guilty? :) >> >> 73! Alex UR5LAM >> _______________________________________________ >> 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 |
Re: It have to work better!
|
|
In reply to this post by Eric Swartz - WA6HHQ
Hi Eric,
may be error in schematic, may be in my head. :) Please look on these new plots: here is plot with s9-level signal from XG1 BEFORE replaced W16: http://forum.cqham.ru/download.php?id=32057 and here is plot with s9-level signal from XG1 AFTER replaced W16: http://forum.cqham.ru/download.php?id=32650 Please, any yours comments. 73! Alex UR5LAM Eric Swartz - WA6HHQ, Elecraft wrote: > The schematic is in error. It was found that the coax was unnecessary. > > The levels of signals reported are not audible at greater than 50-60 dB > down from normal signals and do not impact our sensitivity spec. > > 73, Eric WA6HHQ > ---- > > > Barry N1EU wrote: >> Alexander Ponomarenko-5 wrote: >> >>> In original K3 the W16 is monowire (on top of the RF-board), >>> but if we will analyze the scheme, we can see that W16 must be in the >>> screen. >>> The W16 are near non screen-shielded BP-Filters, and we can see >>> second RX-channel on my first web-link: >>> http://forum.cqham.ru/download.php?id=32620 >>> You can get out monowire W16, and replace to new W16 (behind RF-board >>> in our opinion). >>> You must to use coaxial-cable for W16. I'm used silver-plated >>> screen-shielded video-cable from Supra. >>> >>> >> Yes, that seems correct Alex. >> >> The K3 schematic clearly shows that W16 is supposed to include a grounded >> shield. >> 73, >> Barry N1EU >> >> > _______________________________________________ > 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 |
|
|
Alex,
From what I see on your plots, the frequencies of the spurs have changed. On the BEFORE plot, I see a main signal at -9dB and the 2 major spurs are -78 dB at 10.4 kHz and another at -77 dB at 12.6 kHz. The difference between the main signal and the greatest spur is 68 dB. On the AFTER plot, I see the main signal at -27 dB, but there are 2 major spurs - one at -85 dB at 5 kHz and another at -88 dB at 10.4 kHz. The difference between the main signal and the greatest spur is now only 58 dB - all in all a worsening of the signal to spur ratio. 73, Don W3FPR Alexander Ponomarenko wrote: > Hi Eric, > > may be error in schematic, may be in my head. :) > > Please look on these new plots: > > here is plot with s9-level signal from XG1 BEFORE replaced W16: > http://forum.cqham.ru/download.php?id=32057 > > and here is plot with s9-level signal from XG1 AFTER replaced W16: > http://forum.cqham.ru/download.php?id=32650 > > Please, any yours comments. > > 73! > Alex UR5LAM > > > Eric Swartz - WA6HHQ, Elecraft wrote: >> The schematic is in error. It was found that the coax was unnecessary. >> >> The levels of signals reported are not audible at greater than 50-60 >> dB down from normal signals and do not impact our sensitivity spec. >> >> 73, Eric WA6HHQ > 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 |
|
|
Good point Don. Similarly, I noticed in the original post that, while the noise floor in the "fixed" case was flatter, it was also 10dB higher than the non-modified version, apparently masking the issue, not fixing it.
here is plot BEFORE "modification" (you can see terrible "spur" near
12kHz) http://forum.cqham.ru/download.php?id=32620 here is plots AFTER "modification": http://forum.cqham.ru/download.php?id=32621 Chad WE9V On Mon, Nov 24, 2008 at 3:47 PM, Don Wilhelm <[hidden email]> wrote: Alex, _______________________________________________ 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: It have to work better!
|
|
In reply to this post by Don Wilhelm-4
Don,
yes, after replaced the W16 the difference between the main signal and the greatest spur is similar "before". But we can see, that quantity of spurs are much less. Here is plots from Line-Out: before replace the W16 : http://forum.cqham.ru/download.php?id=33328 and after replaced the W16 : http://forum.cqham.ru/download.php?id=33327 73! Alex UR5LAM Don Wilhelm wrote: > Alex, > > From what I see on your plots, the frequencies of the spurs have changed. > > On the BEFORE plot, I see a main signal at -9dB and the 2 major spurs > are -78 dB at 10.4 kHz and another at -77 dB at 12.6 kHz. The > difference between the main signal and the greatest spur is 68 dB. > > On the AFTER plot, I see the main signal at -27 dB, but there are 2 > major spurs - one at -85 dB at 5 kHz and another at -88 dB at 10.4 kHz. > The difference between the main signal and the greatest spur is now only > 58 dB - all in all a worsening of the signal to spur ratio. > > 73, > Don W3FPR > > Alexander Ponomarenko wrote: >> Hi Eric, >> >> may be error in schematic, may be in my head. :) >> >> Please look on these new plots: >> >> here is plot with s9-level signal from XG1 BEFORE replaced W16: >> http://forum.cqham.ru/download.php?id=32057 >> >> and here is plot with s9-level signal from XG1 AFTER replaced W16: >> http://forum.cqham.ru/download.php?id=32650 >> >> Please, any yours comments. >> >> 73! >> Alex UR5LAM >> >> >> Eric Swartz - WA6HHQ, Elecraft wrote: >>> The schematic is in error. It was found that the coax was unnecessary. >>> >>> The levels of signals reported are not audible at greater than 50-60 >>> dB down from normal signals and do not impact our sensitivity spec. >>> >>> 73, Eric WA6HHQ >> > 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 |
«
Return to [K3]
|
1 view|%1 views
| Free forum by Nabble | Edit this page |