[time-nuts] PRS10 case temperature

[Scott Mace via time-nuts]

I have been experimenting with a PRS10 and using Lady Heather to collect data. This unit had several failed components in the lamp assembly, which I replaced and the unit locks well now. One thing I noticed is that on cold startup, the unit seems to think it's already at 40-50C, when in reality it's only slightly above room temperature. The sensor settles around 79-82C. I've measured the baseplate and it is around 50C. I believe that all of the ovens are running slightly low as a result (if I understand the circuit correctly). I'm thinking that the case temp sensor, a LM45C, on the power supply board is bad. Anyone else running a PRS10 with reasonably correct baseplate temperatures?

Here are some of the numbers I'm seeing:

AD1 - Heater supply : 24.360V
AD2 - +24V supply: 24.370V
AD3 - Lamp FET drain: 4.910V
AD4 - Lamp FET gate: 4.080V
AD5 - OCXO heater: 1.811V
AD6 - Cell heater: 2.101V
AD7 - Lamp heater: 1.513V
AD8 - Photo signal: 3.831
AD9 - I/V converter: 4.804V
AD10 - Case temperature: 80.80 C
                         ^^^^
AD11 - XTAL thermistors: 0.961
AD12 - Cell thermistors: 0.971
AD13 - Lamp thermistors: 0.972
AD14 - Freq cal pot: 2.337
AD15 - Analog ground: 0.005V
AD16 - TXCO varactor: 7.240V
AD17 - VCO varactor: 11.520V
AD18 - Multiplier gain: 11.520V
AD19 - RF synth lock: 4.900V



        Scott

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