if its the yellow tantalum. then yes 39 uf at 10V. Soooo sort of surprised it didn't go nuclear on you. Makes for a serious mess. Regards Paul WB8TSL
On Sat, Oct 29, 2016 at 9:59 AM, Bob Camp <kb...@n1k.org> wrote: > Hi > > If the OCXO was designed for a ~70 C upper end temperature spec, then a > ~90C crystal > would make sense. > > When you feed +12 into the oven control, you are increasing the effective > gain of the control > loop (it has more power). The cycling you see is the loop going into > oscillation. It’s the same thing that happens if > you put way to much insulation around an OCXO. > > I *hope* the 4 amps below is a typo. 20W into the beast is way to much. > 0.4 A at 5V would be > 2W. That is a fairly normal number for an OCXO like you have at room > temperature. > > Bob > > > > On Oct 29, 2016, at 9:51 AM, Peter Reilley <preilley_...@comcast.net> > wrote: > > > > More information; > > > > I added a picture to the dropbox from my Flir IR camera. The picture > shows the copper block > > that the crystal is attached to running at about 200 F. In the IR shot > the copper block is to the > > right. In most of the regular pictures it is toward the bottom of the > picture. This is with the > > unit (minus the S30 chip) running on 5 volts for more than 10 hours. > Is that too hot? > > > > While running at 5 volts the current is constant at about 4. amps, no > cycling. At 12 volts > > it cycled between .9 to .1 amps. I would not expect cycling for the > temperature control > > of an OCXO. I would expect a linear temperature control circuit. > > > > I looked at the tantalum capacitor on the bottom of the board. The > marking is 39-10. > > Does that mean 39 uF and 10 volts? If so then it must be a 5 volt > unit. The capacitor > > did not explode at 12 volts. > > > > Dropbox link: > > https://www.dropbox.com/sh/52e9d1rva9kpb3w/ > AABmbIj1aK7Zk2J9SNMmu-JAa?dl=0 > > > > Pete. > > > > On 10/18/2016 9:11 AM, Peter Reilley wrote: > >> I bought an Isotemp OCXO82-59 with a frequency of 10 MHz for a $3 at > the MIT flea market. > >> As expected it was dead. It heats up as expected but looking at the > output with a scope there > >> is nothing. However looking at the output with a spectrum analyzer I > can see a faint 10 MHz > >> signal. It seems that the oscillator is running but the output > circuitry is dead. Reasonable > >> assumption? > >> > >> Anyway, has anyone had any luck unsoldering the tin case without > destroying it? > >> > >> Pete. > >> > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@febo.com > >> To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > >> and follow the instructions there. > >> > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.