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| HP 5335A Timer / Counter - Anything i should know? |
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| tkamiya:
I wonder if my oven module is damaged.... I expected outside metal to be warm to hot. It's not even luke warm. It's same temperature as other components.... The upward trend is still continuing. |
| 0culus:
--- Quote from: tkamiya on February 20, 2019, 03:22:06 am ---I wonder if my oven module is damaged.... I expected outside metal to be warm to hot. It's not even luke warm. It's same temperature as other components.... The upward trend is still continuing. --- End quote --- Yeah, that's not right at all. All of the ones I have (5335A, 2x 8568B RF sections, 3325B function gen) all are quite warm to the touch when the oven has had wall power for a while. |
| tkamiya:
That's what I thought. Most of them gets hot enough that it's uncomfortable to touch for long. Darn! Now it explains why it's behaving oddly. Tomorrow, I'll check 24V first, then start looking. |
| 0culus:
Here's a little experiment I did that might give you a datapoint. The 3325B has been unplugged for a couple of days, so I plugged it in and started monitoring a 10 kHz 0 dBm sine with the 5335A (which has been on power for about a week now). Took about 1.5-2 hours but the 3325B oven settled out reasonably well after pretty considerable swings when it was first turned on. I believe it may take quite a bit longer than that to truly settle, but at the same time, once the oven gets to temp it should stabilize a lot. |
| Dr. Frank:
The 10811 has to get warm, otherwise the oven is not working. Strange, that you can trim to zero anyhow. So, what is the rate, anyhow, and how / what do you measure in practise? The 10811 is stable only after 48h, as I wrote already, and will be stable then to about 1E-9, maybe more, if it has been off for a longer time. To check the oven, you may apply 24V to the oven circuit externally, that should consume 500mA on power on, going down to around 2..4W after 15 min, or so.. If not, the internal thermal fuse may be defect, what often happens on vintage 10811. It can be replaced by a short w/o problem. Frank |
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