Thanks a lot Don and Ed, I will be working on it over the weekend and will report back.
73, Tom On Fri, Jan 18, 2019, 10:33 AM Don Wilhelm <[email protected] wrote: > Tom, > > Normally I would say to spread or compress the turns on T5, but Elecraft > encountered a batch of J310 FETs that do not work very well at Q19 - the > PLL reference oscillator. These troublesome FETs have now been purged > from the Elecraft stock, that the problem should go away going forward. > I am not sure that is your problem, but it is worthy of checking. > > First question is - did you get good frequency readings for the PLL > Reference Oscillator range? If it fails, you see a strange frequency > reading at the high frequency end (when BAND+ is tapped). > Now, the other "funny" thing is that it sometimes checks OK with the > internal counter probe plugged into TP3, but fails when the probe is > removed. > > Under those conditions, the PLL and VFO do not lock together > > So the first thing to try is to solder a 10 to 15pF capacitor between > the source of Q19 and ground. Then between a combination of adjusting > the red turns on T5 and L30 see if you can obtain the correct R30 voltage. > > If that is successful, then all should be well. > > If not successful, get a replacement Q19 from Elecraft. Send the part > number and description to [email protected] and ask for a replacement. > > If that does not correct things, then email me and we can go through > some other checks to determine the source of the failure. > > 73, > Don W3FPR > > On 1/18/2019 8:48 AM, K2bew wrote: > > Don et al, > > > > Since I know Don monitors the reflector as well as the support emails, > > rather than email Don directly I thought I would ask the question on here > > because I know I always find it helpful to read other peoples questions > on > > here and Don's answer. > > > > Building the K2 I am at the VCO Alignment voltage check on R30 and > > adjusting L30. > > VFO frequency set at 4000.00 kHz > > I initially got 3.5 volts and bottomed out L30 to get it to 5.5 volts, > and > > then I over screwed it to try to get that last half a volt and ended > > damaging it, so, then I carefully took out L30 and put in a new one. > > > > I also took out T5 and rechecked all the ends for continuity, rewound the > > green wire to space it exactly in the middle of the red winding and > spaced > > everything evenly. I confirmed it is the large yellow core, I have 16 on > > the red wire and 4 on the green (by the way the illustration shows 14 > turns > > of red) . I verified I have R30 as Br-R-Br 120 ohms with both my DVM and > by > > color, and I verified C72 is 271, and I reflowed the solder on both. > > With a new 4.7 inductor (large slot, no red mark) in L30 I now get 2.75 > > volts on the left side of R30 to start with and it bottoms out at 4.5 > volts > > (I was very careful to not bottom it out too hard this time and damage > this > > one, and I have already ordered a couple new ones from Elecraft). > > > > What else can I do to increase that voltage? Would changing the number of > > windings on T5 change it enough to get to 6 volts? > > > > Thank you and 73, > > Tom Bewick K2BEW > ______________________________________________________________ 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]
