K2 - RF Board part 2
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Hello Elecraft(ers)!
I just wrapped up part II of the RF board assembly, test, and alignment. I was elated to discover that all the VCO values were in range and that I could hear my KX1 screaming in the headphones attached to the K2. But I have a question - I brought the K2 upstairs and attached it to my outdoor dipole... verified that there was plenty of activity on 40m with my FT840... but didn't hear a THING in the K2. Didn't even hear a blip when I removed/re-attached the antenna cable. I am guessing that the circuitry isn't built up enough to bring in signals generated more than a few feet away, but I don't know... I don't feel that I have the RF electronics background necessary to build this thing, but I'm darn good at soldering and construction :) Should I be concerned or should I move on and finish this thing?? I completed the KX1 this past fall... only made one contact (due to time/effort constraints) but it was a good 300 miles away or so... so I'm really excited to get this rig on the air!! _______________________________________________ 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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At this point of construction, the 40 meter receiver should be as good
as it gets - the following assembly only adds the other bands and the transmit section. You do have a problem somewhere that should be investigated. The easiest first step is to try the "Quick and Dirty Signal Tracing" technique that is in the Builder's Resource page at the Elecraft website. If that does not reveal the area of failure, then one can resort to the Receiver Signal Tracing steps in Appendix E of the manual. 73, Don W3FPR David J. Wallace wrote: > Hello Elecraft(ers)! > > I just wrapped up part II of the RF board assembly, test, and alignment. > I was elated to discover that all the VCO values were in range and that > I could hear my KX1 screaming in the headphones attached to the K2. But > I have a question - I brought the K2 upstairs and attached it to my > outdoor dipole... verified that there was plenty of activity on 40m with > my FT840... but didn't hear a THING in the K2. Didn't even hear a blip > when I removed/re-attached the antenna cable. I am guessing that the > circuitry isn't built up enough to bring in signals generated more than > a few feet away, but I don't know... I don't feel that I have the RF > electronics background necessary to build this thing, but I'm darn good > at soldering and construction :) Should I be concerned or should I move > on and finish this thing?? > > I completed the KX1 this past fall... only made one contact (due to > time/effort constraints) but it was a good 300 miles away or so... so > I'm really excited to get this rig on the air!! > > > _______________________________________________ > 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: 8.0.176 / Virus Database: 270.10.13/1914 - Release Date: 1/24/2009 8:40 PM > > 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 djmd
Hello,
See page 59 of the manual for installation instructions for C6. Ensure that it is indeed soldered into the outer of the two pins i.e. [here][ ][and here] (if the [][][] were to represent the three pins) Merlin
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In reply to this post by Don Wilhelm-4
Alrighty! Bear with me, this is new territory. I followed the signal through the radio per the Cheap and Dirty tracing... cool stuff. I thought I had a problem at C5, as the signal was a bit louder on the other end of C5 (vs. the junction to C4) but I kept going. C228 seems to be where the buck stops. I hear it on C225, I don't hear it at all on C226. On 228 I hear it on the 225 side but not the other side, the junction to 226. Would the first step be to replace this cap?
<quote author="Don Wilhelm-4"> At this point of construction, the 40 meter receiver should be as good as it gets - the following assembly only adds the other bands and the transmit section. |
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Haha!
I skipped over L25 and L26. I'll get those on there and get back to ya'll :) Seriously though, I learned more about the circuit this morning than I have in the whole process of the build, so I'm glad this happened. Wow... |
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Well, now I'm even more confused. I installed those toroids. I checked the pads for connectivity, and they are ok. The signal seems to be present on the "top" pad of L25 and L26, but still nothing on C226 or C227. I guess I should remove them, re-wind them and re-strip/tin? Like I said, I checked them on the DMM but I guess I'm not 100% sure. I'm having way more trouble stripping the enamel off these than I did with the KX1 for some reason. Unfortunately I won't be able to continue till Thursday, as I am heading out of town this afternoon. I will report back then... in the meantime if you have any thoughts, they surely are welcome. 73 K8DJW |
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In reply to this post by djmd
I was just going to tell you to check the lead tinning on L25 and L26
when I saw your note here. Great that you found that omission. 73, Don W3FPR djmd wrote: > Haha! > > I skipped over L25 and L26. I'll get those on there and get back to ya'll :) > > Seriously though, I learned more about the circuit this morning than I have > in the whole process of the build, so I'm glad this happened. > > Wow... > > > > ------------------------------------------------------------------------ > > > No virus found in this incoming message. > Checked by AVG - http://www.avg.com > Version: 8.0.176 / Virus Database: 270.10.13/1916 - Release Date: 1/26/2009 7:08 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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In reply to this post by djmd
If you are having trouble stripping the toroid leads, that is cause to
suspect that they are the problem. If you are using the 'solder blob' method, remember to increase the heat on the iron - at least 800 deg F or even 850. Wait until the enamel starts to smoke a bit before moving the lead through the solder blob. 73, Don W3FPR djmd wrote: > Well, now I'm even more confused. I installed those toroids. I checked the > pads for connectivity, and they are ok. The signal seems to be present on > the "top" pad of L25 and L26, but still nothing on C226 or C227. I guess I > should remove them, re-wind them and re-strip/tin? Like I said, I checked > them on the DMM but I guess I'm not 100% sure. I'm having way more trouble > stripping the enamel off these than I did with the KX1 for some reason. > > Unfortunately I won't be able to continue till Thursday, as I am heading out > of town this afternoon. I will report back then... in the meantime if you > have any thoughts, they surely are welcome. > > 73 > K8DJW > > 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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Yeah, that was more or less it. I remembered that when I did the KX1 I used a much bigger tip on the iron, so I switched to that and it worked just like I remembered. So now I am definitely hearing the outside world loud and clear. However, this has brought to attention a couple new problems.
First of all, very strange noises in certain portions of the band. They seem to disappear suddenly while I am tuning. Hard to explain, it's not any kind of noise that I have ever heard before... hopefully it's related to this problem: When listening to CW (and SSB) signals and tuning across the band, the pitch of the heard signals are staying constant... it's like the frequency is only changing every so often, not steadily as I move up and down. A friend is saying it's probably a VCO issue. Just to be clear, all VCO voltages were in range when I checked them yesterday. I will be unable to work on the radio until Thursday afternoon, but would love to know what I should be checking when I get back. Thanks for all the help!
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The first thing you should do when you get back to it Thursday is to put
the bottom cover on (using all 6 screws) if it is not already mounted, and then run CAL PLL. That should set your tuning straight. Right now it would appear that you have random data in the EEPROM, and a CAL PLL run will straighten that out by storing new values. You might also strongly consider also using CAL FIL to move to each BFO in turn and change its frequency slightly (set it back to the original if your filters are already set correctly). Doing that will cause the K2 to store new values in the EEPROM for the BFO frequencies. If that does not cure the tuning issue, then please ask again and we can provide some troubleshooting aid. 73, Don W3FPR djmd wrote: > Yeah, that was more or less it. I remembered that when I did the KX1 I used a > much bigger tip on the iron, so I switched to that and it worked just like I > remembered. So now I am definitely hearing the outside world loud and clear. > However, this has brought to attention a couple new problems. > > First of all, very strange noises in certain portions of the band. They seem > to disappear suddenly while I am tuning. Hard to explain, it's not any kind > of noise that I have ever heard before... hopefully it's related to this > problem: > > When listening to CW (and SSB) signals and tuning across the band, the pitch > of the heard signals are staying constant... it's like the frequency is only > changing every so often, not steadily as I move up and down. A friend is > saying it's probably a VCO issue. Just to be clear, all VCO voltages were in > range when I checked them yesterday. > > I will be unable to work on the radio until Thursday afternoon, but would > love to know what I should be checking when I get back. Thanks for all the > help! > > > > Don Wilhelm-4 wrote: > >> If you are having trouble stripping the toroid leads, that is cause to >> suspect that they are the problem. If you are using the 'solder blob' >> method, remember to increase the heat on the iron - at least 800 deg F >> or even 850. Wait until the enamel starts to smoke a bit before moving >> the lead through the solder blob. >> >> 73, >> Don W3FPR >> >> >> > > > ------------------------------------------------------------------------ > > > No virus found in this incoming message. > Checked by AVG - http://www.avg.com > Version: 8.0.176 / Virus Database: 270.10.13/1916 - Release Date: 1/26/2009 7:08 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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In reply to this post by djmd
djmd wrote:
> > Well, now I'm even more confused. I installed those toroids. I checked the > pads for connectivity, and they are ok. The signal seems to be present on Both ends of the filter are grounded when the filter is not selected, and the power off relay positions are not defined (probably last setting). That could give a false indication of continuity. > the "top" pad of L25 and L26, but still nothing on C226 or C227. I guess I > should remove them, re-wind them and re-strip/tin? Like I said, I checked > them on the DMM but I guess I'm not 100% sure. I'm having way more trouble > stripping the enamel off these than I did with the KX1 for some reason. > -- 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 |
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In reply to this post by Don Wilhelm-4
Thanks Don, this did the trick!
Unfortunately I can't test it again on the dipole... mother nature decided to dump an inch of ice on us which weighted down the antenna and took down the mast holding up one end of it..... booo... I'm still a little bit concerned about the strange noises I was hearing on and off throughout the band when I was connected to the big antenna. But I think I am just going to start part 3.
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