Crystal oven.

[dr pepper]

I want to build a vcocxo, I have built a satisfactory voltage trimmed xtal osc, now I need to put the xtal in an oven.
I have a very old but serviceable cathodeon oven, the connections to the xtal would mean having leadout wires to the board, 1 to 2", do I run 2 wires direct back to the 'hc00 chip oscillator or should I twist them?.
I'dve liked to have put the 'hc and everything in the oven but it wont fit, I'm not totally sure theres any benefit as the laoding caps and the varactor diodes being outside the oven will be subject to temp changes and thermal drift still might be an issue.

 

[MikeMl]

TXCOs typically put the entire oscillator and a buffer inside the oven, sometimes even the voltage regulator.

 

[dr pepper]

Yes, but didnt know about the reg.
Might be better not bothering then, the osc is disciplined anyway.

 

[ChrisP58]

TI and Fairchild, and others probably, make single gate versions of all the classic parts in very small packages.

The SN74AHC1G00 is a single gate version of the HC00. It is available from TI in a 5 pin SOT-23, or the even smaller SC70. That might be small enough to fit it all in your oven.

 

[MrAl]

I want to build a vcocxo, I have built a satisfactory voltage trimmed xtal osc, now I need to put the xtal in an oven.
I have a very old but serviceable cathodeon oven, the connections to the xtal would mean having leadout wires to the board, 1 to 2", do I run 2 wires direct back to the 'hc00 chip oscillator or should I twist them?.
I'dve liked to have put the 'hc and everything in the oven but it wont fit, I'm not totally sure theres any benefit as the laoding caps and the varactor diodes being outside the oven will be subject to temp changes and thermal drift still might be an issue.

Hi,

You're going to need a bigger oven

Seriously though, care to show your schematic so we can take a look at this voltage trimmed xtal oscillator circuit?

 

[alec_t]

Can't you use a home-brew oven to house the whole caboodle?

 

[dr pepper]

I'll post a schematic when I'm next near a scanner, theres nothing to it.
I plan to put a meter on the finished design so if the system goes out of its control range the meter will at least show it.

 

[dr pepper]

I finished the frequency standard, I didnt use an oven as the circuit controls the xtal over its 100ppm operating range.

I did however get this, for another project, its an ex air force frequency standard, It has a nice large platform on a brass base within, the temp feedback is from a ra53 mounted on the brass base, theres enough room for a piece of vero and a pic/10mc xtal/varicap. Maybe I'll put a ds18b20 in there with rs232 temp data from the pic.

Unfortunately I think I blew the temp control circuit, thinking it was just 2 wires to the heater I bunged 60 v up it, but its made from bc107's and a bfy51 so shouldnt be hard to sort.