On 12 January 2017 at 02:31, Bob Camp <kb...@n1k.org> wrote: > Hi >
Hi Bob > > The most basic issue you are going to run into is that your counter is not > high enough > resolution / accuracy to give you meaningful data for time intervals under > a few hundred > seconds. Is that true if I'm not testing very high quality sources? There are significant differences observed between these two setups 1) START and STOP from distribution amplifier. 2) START from distribution amplifier. STOP from Stanford Research SR345 30 MHz function generator set to produce 10 MHz. 1) ADEV plot at http://www.kirkbymicrowave.co.uk/time-stuff/ADEV.PNG where ADEV is about 5x poorer on the function generator at 100 seconds 2) MDEV plot at http://www.kirkbymicrowave.co.uk/time-stuff/MDEV.PNG where MDEV is about 5 x poorer on the function generator at 10 seconds. The raw data is in the same directory http://www.kirkbymicrowave.co.uk/time-stuff/ . I should have zipped that, as it is quite large I'm pretty sure the HP 83623A 20 GHz sweep generator will be a lot worst than either of those, as a simple check of the standard deviation on the display of the HP 5370B (no data collected from GPIB), showed much higher SD on the microwave sweeper than the function generator. I can see if I were testing masers, Cs source, and decent GPS receivers, what you say would be true. But is it true for lesser quality sources? Maybe testing lesser quality sources is not such a stupid idea, as the instrumentation is less of a limiting factor. I admit I did say in my original post SHORT/MEDIUM time scales, and I guess 10/100s is not short. > I would focus on improving on that part of things before I went off on a > major > “test everything” adventure. But is there any way without spending lots of cash? The following instruments are out of the question due to price * Keysight 53230A 350 MHz Universal Frequency Counter/Timer, 12 digits/s, 20 ps * John's Timepod A Stanford Research SR620 is not out of the question. I did have one before, but swapped it, along with a 4.2 GHz signal generator for an HP4391B impedance/material analyzer. The 5370B came along fairly cheap ($300), but I don't mind spending more on a SR620. But will that gain me much? I know the single shot resolution is a bit better than the 5370B, but it does not appear to be a massive improvement, given they are 3~4 x the cost.on the used market. I also have many other contraiints, which limit what I can realistically achieve * Small lab in my garmage- opening door on lab will change temperature. * Single glazed window * Air con that is a standard unit designed for offices - not metrology labs. Simply collecting a lot of data that is resolution limited is > not a lot of fun ….. > Agreed. But am I doing that at > 10 seconds? Is the counter my limit on those two sets of data? I will collect some from the HP 83623A 20 GHz sweep generator later today, but that generates a lot of heat, and I'd rather let that warm up for a couple of hours before doing anything with that. > > Bob > You clearly have a lot of knowledge Bob. Can I learn anything useful with what I have, or am I wasting my time? Dave _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.