You probably got them years ago from my same source. HSC Electronics had them pretty cheap in a cardbord bin. They are long gone now... sold out.
Also keep in mind you could run the Ovenair unit un-powered as an insulator... an expensive one but the thermal insulating properties might be very helpful. See you at the super secret lunch in an hour... skipp Glad to be back in one piece from IWCE and Dayton... > "na6df" <[EMAIL PROTECTED]> wrote: > > I have a few Ovenair ovens, physically identical to the hamtronics > unit. They seem to be 60 deg C (140 deg F) ovens, but not verified, > other than with my finger. > Just as an experiment, I stuffed the other transmit rock on a > closeby frequency (from ICM) in the rig, put the oven down over it, > and let it cook for about 20 minutes. It was still pretty close to > on frequency, so I zeroed it, and kept checking every so often. It > is now very stable. I do have a call in to the crystal engineers at > ICM to determine the safe tempurature range for the standard midland > cut rocks, though. I'll wait and see what they say, and post it here. > > I wasn't gonna risk my repeater TX rock for this experiment, so I > just used another that was in the repeater when I got it... > > na6df dave > > --- In [email protected], "skipp025" <skipp025@> > wrote: > > > > The first fix might be to put a non conductive insulator > > over the crystal (xtal). A foam pad or rubber sheeting is > > sometimes used by various mfgrs. Just floating a crystal > > to relative exposed cabinet/box air is not so great if > > the air temp changes more than a small amount. > > > > Second item which might help would be to seal the box > > and possibly insulate it from larger thermal changes as > > mentioned above. > > > > If things get really out of hand, you could find/buy a > > typical Ovenair Crystal unit from various places (like > > Hamtronics) along with the proper Ovenair type crystal. > > I would not put a standard room temp crystal in an Oven > > air unit, nor would I try the xtal heater (resistor) trick > > on a xtal not spec for operation in a heated loop/oven > > circuit. Chances are it's not going to be anywhere close > > to the desired frequency when you heat it to normal xtal > > oven temps... > > > > Keeping in mind the Ovenair unit draws a lot a bit of > > serious current in operation... ie not so great for solar > > only radio sites. > > > > Also note the crystal pins often plug into a tin plated > > holder. It might be prudent to swap the crystal holder pins > > for something better. I use older gold plated transistor > > sockets that can be found surplus or removed from vintage > > salvage. The cheaper xtal socket/pin metal doesn't help > > much as well as the xtal floating in air.... and the exposure > > to mechanical vibration. > > > > I have seen & heard of numerous examples where you could > > modulate a transmitter with modest hits to the outside > > equipment case. > > > > A most funny college example was a friend actually using > > a B&K VFO for Two-Meter operation. Sitting on a firm thin > > table you could actually yell close to the table surface > > and hear the audio on the air. > > > > Your results will probably vary... > > > > cheers, > > skipp > > > > > no6b@ wrote: > > > > > > At 5/23/2006 07:20, you wrote: > > > > > > > > >One other thing you might try - tape a 100 ohm 1 watt resistor > to the > > > >side of the crystal and put 12 VDC across it. Not a pretty > sight, and > > > > > > If you're going to heat the crystal, might as well use something > > that will > > > keep it at a more or less stable temperature: a 50 ohms 50 > degree C PTC > > > thermistor. Digikey has them for $1.68 each (manufacturer part > # > > > RL3006-50-50-25-PTO). Desolder one of the leads & solder the > disk > > directly > > > onto one side of the crystal, ground the crystal case & apply a > > regulated > > > voltage to the other side. > > > > > > Bob NO6B > > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
