Hi Don, As usual, thanks for your assistance. Pulling seven crystals with no super confidence that that's the problem seems hard work. How often does a crystal die? I've not had that fault before in any of my equipment.
I have an XG3 sig gen (known level) and access to a CRO. Is there any level testing comparison I can do to get a sense of where the problem is? Is there a matrix describing switching paths with their inputs and outputs? If not, could you describe the area of the circuit I need to look at and understand. Seems like I need some way of stepping through the combinations and confirming they work / finding what doesn't. Cheers Mike On 25-Jun-12 6:20 AM, Don Wilhelm wrote: > Mike, > > I can see that, but unfortunately, it does not help with the isolation > of the problem. > Ome easy thing you could do is assume a bad crystal in the set on the > base K2 board and try replacing the 7 crystals. If I were to make a > first guess, that would be what I would do. > > OTOH, there may be a problem with the switching path through the KSB2 > diodes that change the path for the two filters. Since you have > already checked the diodes for orientation, that is not as likely as a > faulty crystal. > > 73, > Don W3FPR > > On 6/23/2012 3:09 AM, VK1OO wrote: >> Hi Don, >> >> I've attached a ppt showing FL1-FL4 (Slide 1-Slide 4) responses to >> broadband noise. I could send separate jpg if necessary. >> >> You can see the reduction in signal (audio) between FL1, and FL2-4. >> FL1 sounds louder and has the extra three S Meter bars. >> >> Mike >> >> >> >> On 17-Jun-12 10:19 PM, Don Wilhelm wrote: >>> Mike, >>> >>> >>> >>> >>> >>> OK, back up a step and look at the amplitude of the passband when >>> using Spectrogram. >>> The OP1 filter and the other filters should have close to the same >>> amplitude when the K2 is fed with a broadband noise generator. >>> >>> Please verify for that condition. >>> >>> 73, >>> Don W3FPR >>> >>> On 6/17/2012 7:04 AM, VK1OO wrote: >>>> Don, >>>> >>>> Still no joy with this problem. I've resoldered most of the joints on >>>> the KSB2, checked the torroids etc and have gone back and checked the >>>> filters with a noise generator and spectrogram. >>>> What feature of the circuit would account for the increase in S >>>> meter bars? >>>> >>>> Mike >>>> VK1OO >>>> >>>> >>>> On 10-Jun-12 10:12 AM, Don Wilhelm wrote: >>>>> Mike, >>>>> >>>>> Two different filters - the FL1 OP1 filter is the one on the KSB2 >>>>> board while the others are created from the variable bandwidth filter >>>>> on the RF board. Since all but OP1 work correctly, it has to be the >>>>> OP1 filter on the KSB2 board. >>>>> >>>>> Oh, one more piece of info - when you remove the KSB2 board, the OP1 >>>>> filter goes away, and the filtering defaults to a 2.20 bandwidth >>>>> filter from the filter on the RF Board. >>>>> >>>>> 73, >>>>> Don W3FPR >>>>> >>>>> On 6/9/2012 7:54 PM, VK1OO wrote: >>>>>> Hi Don, >>>>>> >>>>>> Wow, thanks for fast response noting it must be late there. >>>>>> >>>>>> I will do. What conclusion can be drawn from X1 being affected, and >>>>>> not X2-4? >>>>>> >>>>>> Mike >>>>>> VK1OO >>>>>> >>>>>> On 10-Jun-12 9:43 AM, Don Wilhelm wrote: >>>>>>> Mike, >>>>>>> >>>>>>> It is on the KSB2 board somewhere. Check everything on the end of >>>>>>> that board containing the filter crystals. Check T1 and T2 to be >>>>>>> certain all the leads are well stripped, tinned and soldered >>>>>>> and be >>>>>>> sure there are no shorted turns on those toroids. I recently >>>>>>> repaired a K2 that had the shorted turn problem because the builder >>>>>>> use a flame to burn off the insulation from the toroid wires and >>>>>>> got >>>>>>> too much flame on the red T2 wires when he tried to strip the green >>>>>>> leads. >>>>>>> >>>>>>> 73, >>>>>>> Don W3FPR >>>>>>> >>>>>>> On 6/9/2012 7:29 PM, VK1OO wrote: >>>>>>>> Hi Don, >>>>>>>> >>>>>>>> We have a long weekend here, so I've been able to get back to >>>>>>>> this. >>>>>>>> I reflowed RF board and KSB2 board, with no improvement. >>>>>>>> >>>>>>>> I then took out the KSB2, inserting the previously removed links >>>>>>>> and the capacitor (effectively returning radio to pre-KSB2 state). >>>>>>>> The noise problem on X1 goes away. >>>>>>>> >>>>>>>> Your thoughts on what to look at next would be appreciated. >>>>>>>> >>>>>>>> Mike >>>>>>>> VK1OO >>>>>>>> >>>>>>>> >>>>>>>> On 03-Jun-12 6:59 AM, Don Wilhelm wrote: >>>>>>>>> Mike, >>>>>>>>> >>>>>>>>> If you do not find the solution re-flowing the solder on the RF >>>>>>>>> board filter area, the problem source may be on the KSB2 board in >>>>>>>>> the switching diodes and/or resistors at the filter end of that >>>>>>>>> board, so for completeness, reflow those connections as well. >>>>>>>>> >>>>>>>>> 73, >>>>>>>>> Don W3FPR >>>>>>>>> >>>>>>>>> On 6/2/2012 4:24 PM, VK1OO wrote: >>>>>>>>>> Don, >>>>>>>>>> >>>>>>>>>> The effect happens when the antenna is disconnected as well >>>>>>>>>> as when >>>>>>>>>> connected. >>>>>>>>>> And in SBB and CW >>>>>>>>>> >>>>>>>>>> SSB Filter Widths >>>>>>>>>> X1 = OP1 >>>>>>>>>> X2 = 2.4 >>>>>>>>>> X3 = 2.1 >>>>>>>>>> X4 = 1.8 >>>>>>>>>> >>>>>>>>>> CW Filter Widths >>>>>>>>>> X1 = OP1 >>>>>>>>>> X2 = 0.7 >>>>>>>>>> X3 = 0.4 >>>>>>>>>> X4 = 0.1 >>>>>>>>>> >>>>>>>>>> I assume something is going wrong in the 4.915MHz Variable >>>>>>>>>> Bandwidth >>>>>>>>>> Crystal Filter. >>>>>>>>>> >>>>>>>>>> >>>> ______________________________________________________________ >>>> 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 >>>> >>> >>> >>> > > > ______________________________________________________________ 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
