Hui, rent one of each if you can before you make your choice. I have both, and the HP unit is much easier to use once you know which button sequence to push to get more than just "Frequency/Time-Interval" type measurements - these can be single-button events on the HP unit. Even offsetting and normalizing frequencies becomes very easy after a couple of days of using the unit, there is no setting that takes me longer than about 5 seconds to set up, so while not perfect, the user interface can be learned easily. I find the SR620 to have too many buttons(!) I always find myself searching for just that one button. Anyways, more buttons are just more things that can fail. If you are a pilot, and have used a Garmin 430W GPS in your life, then the HP user interface is no challenge whatsoever and seems very easy to use.. The SR-620 has it's advantages, especially when you just do one single type of measurement, but for me it has a huge number of disadvantages, and I mostly use the 53132A for that reason: 1) I paid quite a bit of money and I had it "calibrated" and fixed by SRS, and it still exhibits a significant frequency offset with a "perfect" reference and "perfect" DUT!!! SRS says a small frequency error is "normal", well that prevents me from using the unit as a frequency counter, for me it's only useful as a relative display frequency counter. HP doesn't have such a frequency error, so no worries there. 2) The SRS unit is soooo loud that it's totally annoying and unacceptable for long measurements. Many folks reported this here before. It's just bad. Whining like crazy. 3) The SRS unit is 19" wide, huge, heavy, and clunky. I need my counter portable, only the HP unit will do 4) The SRS unit has a much lower MTBF because of all the parts inside, and it needs finicky adjustments, see item 1) above. The HP unit either works, or is just dead. Not much to adjust. Different technology generation. And the coolness factor: a nice florescent tube display is so much more modern looking than those clunky old 7-segment LED's.. 5) The SRS unit is usually $1000 more than the HP unit, and you don't know how good the unit is you are buying because of all of the calibration stuff. Usually there is no hit-or-miss issue with the HP units, they either work, or are dead. That said, the HP unit doesn't measure well at 10MHz, so I mostly use a divide-by-two to get one more digit of resolution out of it, and it's time interval resolution is not as good as the SR620. But for time interval measurements I use a Wavecrest DTS unit that blows the SR620 and the HP out of the water anyways.. Bye, Said In a message dated 2/7/2013 16:39:04 Pacific Standard Time, ba...@163.com writes:
Hello Dear Group: I am very glad to see so many replies in the morning, and I am very grateful to every time nuts gave me useful information, your proposal has strengthened my determination, in fact, I am also very like SR625, So I will to find and buy a good shape SR625 for my new time interval measure instrument. Thanks again for everyone's advice, which is very useful to make a choice for me. Sorry for not reply everyone's mail. Best Regards! Hui Zhang _______________________________________________ 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.