Mike, I’ve done some of these mods, but not all.
I replaced the MAR6 this morning and it now hears a little better, but the S-meter on the K3 is not moving. Q3 is next. AND I JUST REMEMBERED!!! When I was setting up the rover before the contest, I was keying all the equipment with the antennas attached to check power output, listen to local beacons, etc. The XV222 was receiving OK. I then transmitted and in a few seconds blew the 5A fuse in my WestMountain Radio distribution block. I intended on commenting it to a 10A PP connector but “missed”. I replaced the fuse and went roving. I wonder whether maybe that caused some TX energy to get back into the RX circuit? Oh well, the MAR6 is replaced and I’ll get a new ATF. The crazy thing is that I did not think of this until last night when I had everything on the bench. 73, Mark K2QO FN03ra > On Sep 17, 2020, at 10:54 PM, M Cresap <[email protected]> wrote: > > Hi Mark > > Yes, the XV432 transverter needed a few fixes to work reliably. NT4RT wrote > an excellent article on how to improve the performance of the XV432 (which I > see you have found already). My XV432 is extensively modified with my own > fixes, most of NT4RT's fixes, and K9YC's recommended "Pin 1 problem" fixes > (i.e. rebuild the back panel). > > For the XV222, the first thing I would do to hook up your noise generator to > the RF input and try to adjust R13 for about 250 mV on TP2. See if that > improves your ability to receive the noise generator. I found that the gain > varies a LOT as R13 is adjusted. Be careful not to mistakenly tweak R10, > which is nearby! Don't ask how I know that :-( > > Let me know if that helps. > > 73, Mike, W3IP > > On Thursday, September 17, 2020, 10:29:59 PM EDT, Mark Adams > <[email protected]> wrote: > > > Thanks Mike. I built this along with the XV432 a LONG time ago :-) The 432 > unit had loads of issues. My rover partner, a EE grad from 1964 who designed > military radios and antennas for a living was not impressed with either of > these transverters, especially the XV432. For a hobby, he checks the math in > QEX articles. One time he told me that the author mis-applied Maxwell’s > equation and he ran his own set of differential equations to prove the point. > > On to the my results: > > >> On Sep 17, 2020, at 9:44 PM, M Cresap <[email protected] >> <mailto:[email protected]>> wrote: >> >> Take off the top cover of the transverter, check the voltage between TP2 and >> ground (should be between 200 to 275 millivolts). That measures part of the >> source voltage of Q3, the first receiver amplifier. > > > 65mV > > >> >> Find R16 (a 120 ohm resistor) and measure the voltage to ground on each side >> of the resistor. One side should be 12 volts, the other should be about 5 >> volts. That measures the series dropping resistor for U1, the second >> receiver amplifier. R16 will normally be very warm to the touch. > > > 13.8 and 4.9V > > >> >> If those measurements are correct, the problem is most likely elsewhere. >> >> You can check the condition of the local oscillator by measuring the voltage >> between TP1 and ground. It should be between 1.0 and 1.5 volts. > > > 0.92V > > > Additionally, TP1 is 0.76V, not the minimum 1V. > The output pin of U1 is 0V, not 3.0-6.0V. > > > > >> >> >> >> >> On Thursday, September 17, 2020, 8:58:35 PM EDT, k2qo <[email protected] >> <mailto:[email protected]>> wrote: >> >> >> During the recent September VHF contest I could only hear the absolute >> strongest local stations on the XV222/K3 in my rover. It worked FB in June. >> My XV432 worked just OK as usual. Stations told me I was the loudest signal >> on the 222 band so the TX side is fine. >> >> I put it on the bench and connected my Elecraft N-Gen. When turned on I >> could barely detect an increase in noise. Tried the same on my XV432 and it >> went from S0/1 to a solid S9. >> >> I'm guessing that I somehow blew up U1 (an ERA6) and/or Q3 (an ATF 34143). I >> don't have a good scope, RF generator, or RF voltmeter but kinda think >> replacing both will fix my XV. A bad relay is an option too. >> >> Thoughts? I'd like to fix it to have for a spare as I plan on moving >> non-BigE transverters for 222 and 432. >> >> 73, >> Mark K2QO >> NF2RS/R for the September VHF >> >> >> >> -- >> Sent from: http://elecraft.365791.n2.nabble.com/ >> <http://elecraft.365791.n2.nabble.com/> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> <http://mailman.qth.net/mailman/listinfo/elecraft> >> Help: http://mailman.qth.net/mmfaq.htm <http://mailman.qth.net/mmfaq.htm> >> Post: mailto:[email protected] <mailto:[email protected]> >> >> This list hosted by: http://www.qsl.net <http://www.qsl.net/> >> Please help support this email list: http://www.qsl.net/donate.html >> <http://www.qsl.net/donate.html> >> Message delivered to [email protected] <mailto:[email protected]> > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
