[time-nuts] PRS 10 and serial port communication

[Bob Camp]

Hi

I seem to have a lot of experience running Rb’s without heatsinks. No matter how many chickens I sacrifice at the full moon, the results seem to always come out the same. If you don’t get the temperature of the internal baseplate down under 40C (with a heatsink and maybe fan) they die. These little guys all get very hot. They have to dump heat to keep the offset between the two sections of the physics package at the right offset. No matter what the brand, they run for a year or four and croak. The average is about two years.

One *would* think that I’d stop this experiment ….unfortunately, I have help from others who also seem to believe in the power of the chickens as opposed to heatsinks. 

Bob

> On Mar 8, 2016, at 2:36 AM, Mike Cook <michael.cook at sfr.fr> wrote:
> 
> 
>> Le 8 mars 2016 à 01:56, Philip Zahariev via time-nuts <time-nuts at febo.com> a écrit :
>> 
>> Hello group,
>> 
>> I have significant progress with generator. And there were new questions :-)
>> Frequency was little bit higher than 10 MHz - after correction of PLL constants SP and MO now is just on spot. 
>> 
>> In documentation is not clear described what is active state of signal 1PPS_IN. I found that signal must be 1 and goes to 0 during PPS pulse. After experience with SERIAL line inverter this time was easy (and have free inverters). Opposite is situation of output 1PPS_OUTPUT - his state is 0 and goes 1 during PPS pulse :-)
>> 
>> 1. I found that AD8 - Amplified ac photosignal is changing between 1.120 to 3.991 and any value are different than previous, sometimes jumps are more than 2.xxx (monitoring with RBMon) - Is this usual?
> 
> I think so. At least I have that order of variability on mine. 
>> 
>> 2. AD10 - Case temperature (10 mV/°C) has value 0.781 which means 78°C. I remember that temperature has to be below 40°C, but when mount 2 heatsinks from computer CPU (socket 370) temperature decrease to 67-68°C. Do I need to install fans (don't like noise) or increase size? Are this 40°C was measured with external thermometer or means that AD10 need to be lower than 0.4xx? 
>> 
> 
> My PRS10s are in the same ball park (0.736) on one I am looking at. I have installed SRS supplied Bench Heat Sinks on them and the measured external baseplate temperature is 42.9°. If it’s good enough for SRS then it’s good enough for me though I suspect that within reason lower is better. However, that said, I don’t think that SRS put a fan in the 725 which is a PRS10 + buffered outputs and that is in a case where temps are likely to be higher..
> 
>> 3. Firmware of my device is 3.15. Before value for TO - Time-tag offset (1816) from RBMon has Red square. According manual in this version of firmware TO is not user changeable. Is it available file with new firmware version? Processor on device is MC68HC711E20CFN3 - that means I need to buy new empty processor and program it. What improvements was made in newer version of firmware?
>> 
> 
> That is not strictly true. With 3.15, you should be able to change the current value but you cannot write it to EEPROM (TO!) so that the new value is used at power on. With later versions ex. 3.24 you can change the EEPROM value. 
> 
> I am not sure why it is flagged RED as from my experience the colors used are.
> None:   in spec or not different from EEPROM
> Black:   different from EEPROM value
> Blue:     nearing a limit.
> Red:     Out of spec (ex. SF hit the wall at -2000)
> 
> Equally the black flag on your FC values is strange as the stats value is in limits. If you use FC!? to see what the EEPROM values are you will see 4 values, including the stats figure. From the one in front of me:
> 47		number of power cycles
> 5168	number of times DAC values written to EEPROM ( twice a day from my experience so you can get a rough idea of accumulated power on time)
> 1532	high and        
> 2056	low DAC values used at reset/power on
> 
>> Best regards
>> Philip
>> 
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