XV222 Mods Question
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Greetings,
I recently purchased a used XV222 that had some modifications done in the local oscillator circuit. The construction was very sloppy, but transverter works OK most of the time. Power output is adequate with good audio on SSB and receiver sensitivity seems OK. Sometimes the xvtr goes in to parasitic oscillation. I can stop the oscillation by touching certain parts of the case, and it will operate normally for a while. Weird. I cannot find any documentation about the mod on line. It appears that two 2.2 pF caps have been added (on the bottom side of the board) in parallel with C12 (10pF), and the collector of Q1 goes above the board directly to Z4 instead of into its hole in the PCB. Has anyone seen this mod or the reason for it documented anywhere? Thank you. ---- 73, Mike Cizek W0VTT New Kid on VHF ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Mike,
Has the paint been cleared from all parts of the enclosure that contact the 2D connectors? If not, that could be reason for your observations. You might want to remove those capacitors to see if all is well without them. I have lots of experience with the Elecraft transverters and do not recall that as a mod. 73, Don W3FPR On 6/10/2021 5:37 PM, Mike Cizek W0VTT wrote: > Greetings, > > > > I recently purchased a used XV222 that had some modifications done in the > local oscillator circuit. The construction was very sloppy, but transverter > works OK most of the time. Power output is adequate with good audio on SSB > and receiver sensitivity seems OK. Sometimes the xvtr goes in to parasitic > oscillation. I can stop the oscillation by touching certain parts of the > case, and it will operate normally for a while. Weird. I cannot find any > documentation about the mod on line. > > > > It appears that two 2.2 pF caps have been added (on the bottom side of the > board) in parallel with C12 (10pF), and the collector of Q1 goes above the > board directly to Z4 instead of into its hole in the PCB. Has anyone seen > this mod or the reason for it documented anywhere? > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Mike Cizek W0VTT
On 6/10/2021 2:37 PM, Mike Cizek W0VTT wrote:
> The construction was very sloppy, but transverter > works OK most of the time. Power output is adequate with good audio on SSB > and receiver sensitivity seems OK. Sometimes the xvtr goes in to parasitic > oscillation. I can stop the oscillation by touching certain parts of the > case, and it will operate normally for a while. Hi Mike, More than 15 years ago, while still living in Chicago, I bought used Elecraft transverters for 50, 144, and 220 MHz, to use with my K2. The two that I had occasion to use were unstable. A simple study of their construction made it obvious why.They were designed and built with Pin One Problems -- RF inputs and outputs are BNC fittings insulated from the shielding enclosure, as badly conceived non-solution to a stability problem lurking somewhere on the PCB, and the isolated BNCs were an inappropriately chosen band-aid. EMC guru Henry Ott talked in his seminars about "the hidden schematic lurking behind the ground symbol," and the unintended current paths that resulted from ignoring it. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Don Wilhelm-5
hi Mike - I checked my notes from field testing the XV222 and didn't see
any C12 mod, and I checked my actual XV222 and didn't find any extra caps there. Regarding Z4... there were a series of Builder's Alerts that came out with mods to be made. It's possible that yours is also a field test and/or some of the mods were not done in your version. Don W3FPR may be better able to talk to that, and to have the Builder's Alerts handy in digital form so I don't have to scan them for you. :) Anyway, Alert #5 says Z4 is supposed to be a 56 ohm resistor. I'll have to dig deeper to see what is up with Q1. 73 jeff wk6i On Thu, Jun 10, 2021 at 3:08 PM Don Wilhelm <[hidden email]> wrote: > Mike, > > Has the paint been cleared from all parts of the enclosure that contact > the 2D connectors? > If not, that could be reason for your observations. > > You might want to remove those capacitors to see if all is well without > them. > I have lots of experience with the Elecraft transverters and do not > recall that as a mod. > > 73, > Don W3FPR > > On 6/10/2021 5:37 PM, Mike Cizek W0VTT wrote: > > Greetings, > > > > > > > > I recently purchased a used XV222 that had some modifications done in the > > local oscillator circuit. The construction was very sloppy, but > transverter > > works OK most of the time. Power output is adequate with good audio on > SSB > > and receiver sensitivity seems OK. Sometimes the xvtr goes in to > parasitic > > oscillation. I can stop the oscillation by touching certain parts of the > > case, and it will operate normally for a while. Weird. I cannot find > any > > documentation about the mod on line. > > > > > > > > It appears that two 2.2 pF caps have been added (on the bottom side of > the > > board) in parallel with C12 (10pF), and the collector of Q1 goes above > the > > board directly to Z4 instead of into its hole in the PCB. Has anyone > seen > > this mod or the reason for it documented anywhere? > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > -- Jeff Stai ~ WK6I ~ [hidden email] RTTY op at W7RN Twisted Oak Winery ~ http://www.twistedoak.com/ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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