[GPS_Standard] Dave's OCXO

[Dick Moore]

The thread is getting long, so I'd like to make some comments without preamble. Bert suggested that the OCXO is likely defective. I concur. 

I have used several different OCXOs in this project -- an HP 10811-xxxx, a knock-off of the 10811 by Cinox, and currently an Isotemp. The 10811 was very erratic as was the Cinox -- both simply refused to stabilize for more than an hour or so, at best. Both exhibited frequency "jumping" and large drift swings. Someday, I may try to reset the oven curve on both units, but it's a tedious job, and I suspect that both have other problems. 

I bought the Isotemp on eBay from l.fluke in China, and it works very, very well. Best, it cost me about $35 delivered. Seems to me that with the relatively wide availability of suitable OCXOs, it would make sense to try another unit, and it's always good to have a spare or two....

As to switching supplies, I tried one that was so noisy it interfered with radio, TV, and wireless phones for hundreds of feet around. Then I picked up a Condor supply that puts out +24V and other .levels. It is very quiet and is perfect for supplying the 78xx regulators that follow. I've been using it 24-7 for several years without incident, and it has no effect of any kind on any of the other high-to-very-high-precision gear that's in the shop. So, quality matters more than type, I think.

Dick Moore