Wasn't there some issue with the 78L09 at some point? I seem to recall replacing the low-power versions with standard 7809s .. I'd have to pop them open to check
de w1rt/john On Fri, Jan 25, 2013 at 9:01 AM, Don Wilhelm <w3...@embarqmail.com> wrote: > Ian, > > Two possibilities occur to me. First, detune the LO inductors L3, L4 and L5 > a bit to give you 3 volts maximum at TP1 and see if it stabilizes. > Secondly, try adjusting L4 a bit. It may be that the adjustment of L4 puts > the crystal right on the 'hairy' edge of oscillation which would make the > frequency unstable. The voltage at TP1 should remain between 1.7 and 3.0 > volts. > > 73, > Don W3FPR > > > On 1/25/2013 3:40 AM, Ian Greenshields wrote: >> >> The LO on my XV432 transverter seems to be very unstable. I think it's >> something more than just temperature drift as the frequency will sometimes >> jump by several kHz. It's almost as if the crystal is hunting between >> different modes of oscillation. >> >> Prodding & wiggling the components in the LO circuit doesn't point to any >> obvious poor connection, although the crystal itself is sensitive to being >> touched, or heated by a finger. The LO alignment voltage at TP1 peaks at >> about 3.3V. >> >> I don't have the temperature oven for the crystal, although I think it's a >> requirement. But I'm concerned about the frequency jumping and a frequency >> drift of almost 10kHz which I would not expect even of a non-temperature >> controlled crystal oscillator. >> >> Any thoughts or pointers as to what could be wrong? >> >> TIA, Ian G4FSU >> > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > 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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
