[time-nuts] Re: DOXCO from Z3801

[ed breya]

I don't recall seeing that anyone ever reported the official temperature 
setpoint for the outer oven. Most of the info on the Z3801A still 
resides on realhamradio.com.

I found in my notes a paper printout of a webpage apparently put up 
someone named Shegnauer, circa 2006, showing the schematic, and some 
info and estimates for the temperature range, and a spice model of the 
control system operation. It's a nice document. I tried to find it 
online now, but it seems to have disappeared over the years. The same 
link showed up in old messages on time nuts and other lists, but it 
appears dead now. It must have been pretty well known, so it's likely 
still floating around out there at some URL or in someone's files. If 
you don't have it already, you should try to find it. I only have the 
paper copy.

Anyway, it was suggested that the outer oven should run around 60-65 deg 
C, while the thermistor is around 16.2 k ohms there. Personally, I 
believe this is too high, and should be around 50-55 deg C or maybe a 
bit more - right near the maximum ambient rating for the Z3801A, 
neglecting any internal box temperature rise. If the performance specs 
are relaxed toward the higher end of operating temperature range, then 
the outer oven may not have to run so high. I don't recall, but think 
that may be the case.

Ed