[time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters
kb8tq at n1k.org
Sat Jul 8 22:48:39 EDT 2017
Based on a quick read of the use of the device, they seem to be relying on it to be << 100 ps
off from “ideal”. How much it being non-ideal matters …. not clear. If you are correcting for various errors
and eliminating both unknown source errors and destination errors it likely gets messy.
> On Jul 8, 2017, at 9:14 PM, Tom Van Baak <tvb at leapsecond.com> wrote:
> I knew we had talked about this before:
> The J06-59992A manual, schematic, app note, and patent are here:
> It was designed for the hp 5370 (20 ps) so perhaps the tolerances are less stringent if only used for hp 53132 (150 ps). Maybe one of you RF guys can tell from the schematic?
> Mark writes:
>> Yes, they do show up... but usually for big-ish bucks. I want to build a small affordable replacement that anybody with a 531xx can have.
> I don't recall them being expensive at all, just unusual. But making a modern one for time nuts is a great idea -- both 5370 and 53131/53132 users. Also, when someone gets around to creating a smart analog front-end to John's TAPR TICC board, your 59992A clone will come in handy.
> Note also this recent document by Bill Riley:
> Hal writes:
>> What does "good" mean?
>> I'd expect the variations due to power or temperature would be easy to measure.
>> Delay through classic CMOS is linear with absolute temperature and inverse linear with supply voltage.
> When John created the TAPR TADD-2-mini board I tested the jitter using a TimePod (integrated phase noise mode). I'm looking for the web page or email now, but I recall it was under 2 ps. This is partly due to the fact that the PIC 12F is a fully synchronous MCU; no tricks with double clock edges or PLL's.
> ----- Original Message -----
> From: "Bruce Griffiths" <bruce.griffiths at xtra.co.nz>
> To: "Mark Sims" <holrum at hotmail.com>; "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Sent: Saturday, July 08, 2017 4:48 PM
> Subject: Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters
>> A run of the mill 2 way power splitter has better than 10ps phase matching at 100MHz there are few digital devices that offer that degree of matching at best they are usually 10x worse.
>>> On 09 July 2017 at 06:58 Mark Sims <holrum at hotmail.com> wrote:
>>> Yes, they do show up... but usually for big-ish bucks. I want to build a small affordable replacement that anybody with a 531xx can have.
>>> My design is currently leaning towards a board with the clock generator and a 5V reference for the gain calibration (they spec 5V +/- 1mV). I was going to use a couple of 2P4T slide switches to route open circuit, 5V, normal clock, and inverted clock to the two output connectors.
>>> I think the cost to build would be in the $20 range and fit on a 2x2" or so circuit board... certainly more attractive than a $500 big ancient box with unobtainium parts in it. The board should be able to perform all the calibration steps for the counter.
>>> I don't think the signal requirements are super critical. They are using 1:2 splitters and splitter/180 degree phase shifters and relays to generate the output signals passively from the inputs. I think a digital clock generator would be a LOT more accurate than those phase shifters.
>>>> Actually, you can get J06 HP-59992A calibrators on eBay.
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