[time-nuts] SR620 testing

[Don@True-Cal]

Guys,

The SR620 X/Y feature is extremely valuable for my time lab. You probably need to rethink the feature after setting up a nice X/Y display and experimenting with the different display features. I use an Rb and distribution amp for my lab 10MHz standard which feeds the external ref input of the SR620. When the TIC is not being used for other things, it has a Thunderbolt with a double-oven OCXO (TC=1200) connected to one channel and the 10MHz ref to the other measuring zero-crossing time difference. Triggering with the TIC 1KHz output and using 1E5 samples sizes makes the horizontal axis approximately 7-hours while the vertical axis is set for 20ns/div allowing visibility of plus/minus 50ns or the whole 100ns phase cycle of the 10MHz after a 50ns reference is set. I added an extremely fine external EFC to my Rb reference and this allows me to make fine enough ref frequency changes to strive for zero-slope displays of many hours and even days. The 20ns/div typically reveals plus/minus 10ns GPS bumps but the overall slope over many hours is what's important. You could do this through the GPIB but you are tying up a lot more resources during the extended runs. My Tektronix 606B display cost me $50 years ago. Take my word, it's worth checking out - don't write off the X/Y outputs. Pictures on request or can someone give me an upload site.

Don

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Bob Camp
Sent: Tuesday, February 23, 2016 6:13 AM
To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
Subject: Re: [time-nuts] SR620 testing

Hi

You may have cleaned up a dirty pot wiper as well …

The SR620 has X/Y outputs? Who knew?  … that’s how often that feature gets used around here.

Bob

> On Feb 23, 2016, at 12:14 AM, Joseph Gray <jgray at zianet.com> wrote:
> 
> Ignore the problem with EXT trigger. I did a factory reset and now it 
> is working. I should have thought to reset it to begin with.
> 
> Joe Gray
> W5JG
> 
> 
> On Mon, Feb 22, 2016 at 8:14 PM, Joseph Gray <jgray at zianet.com> wrote:
>> Finally got an SR620 at a decent price. I'm going through the 
>> Functional Tests and the Performance Tests now. So far, I have two 
>> anomalies.
>> 
>> Pg 62 Functional Test - EXT input. When I vary the EXT trigger knob, 
>> I don't get the trigger LED, except that it flashes briefly at one 
>> spot as I move the knob from high to low.
>> 
>> XY outputs - text at the top is slanted and text near the middle 
>> right is overlaid. I don't know if I care about this, as I am 
>> unlikely to use this feature.
>> 
>> I can't test the printer port. No Epson printer. I probably don't 
>> care about this, either.
>> 
>> Pg 63 Performance Test - Timebase frequency is 15 Hz high. I will adjust later.
>> 
>> Timebase accuracy +/- 0.0035 Hz passes.
>> 
>> This is far as I have gotten. After I get a bite of dinner, I will proceed.
>> 
>> The EXT trigger test not working worries me. Perhaps I am doing something wrong?
>> 
>> 
>> Joe Gray
>> W5JG
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