At 2/3/2007 06:06, you wrote: >>On 2/2/07, Kevin Custer <<mailto:[EMAIL PROTECTED]>[EMAIL PROTECTED]> wrote: > >>But I doubt I'll ever have time to test that possibility. However, it >>might explain why a lot of people have fairly good luck just stuffing >>crystals in ICOM's. There's probably a fairly small range of caps used >>to bring "the usual" crystals into spec... and a good chance that your >>new crystal behaves similarly enough to the original that it will work >>some large percentage of the time. > >I wouldn't say "a lot of people have good luck". Have you seen the amount >of posts on Repeater-Builder and the other radio branded lists on the >subject over the years?
FWIW, I've had both good luck & bad with recrystalling Mastr II ICOMs. I'll also say that they appear to have more than one temperature compensating capacitor in them. The reason I say that is that after installing a PTC thermistor on the crystal to thermally stabilize it, I would still see thermal drift in the oscillator, & replacing just one or two of those little blue capacitors didn't fix it - I had to remove all of them. I think there were 4 of them total in the one ICOM I moded but not sure. I did decide not to try that mod on a Mastr II again though. The MVPs are much easier as they only use 1 temp. comp. cap & for some reason most of the MVP crystal modules I have don't have any at all. I agree that from the end users (the repeater builder) standpoint, sending elements in for temperature compensation is the easiest way to go. The problem I see is with all the talk about declining quality amongst the different crystal vendors today, I really wonder if there's anyone out there that can truly be considered unconditionally reliable. I mean, is there any ONE crystal supplier that EVERYONE considers a "rock" of stability? (pun intended!) I suppose that's partly why I've resorted to developing my own alternative methods of frequency stabilization; file under "if you want something done right, do it yourself". Bob NO6B
