[time-nuts] How does sawtooth compensation work?

David davidwhess at gmail.com
Mon Aug 8 03:24:57 EDT 2016

The DC510 and DC5010 phase lock a 320 MHz varicap oscillator to the 1
MHz reference giving them a 3.125ns single shot timing resolution.

The DC509, DC5009, DC510, and the DC 5010 are reciprocal counters.

The universal timer/counters in the 2236, 2236A, 2247A, and 2252
oscilloscopes phase lock 100 MHz varicap oscillators to their
references and are reciprocal counters which is important since they
can gate their timer/counters which is incredibly handy on a dual
timebase oscilloscope.  The 2247A and 2252 use noise modulation but I
do not think the 2236 and 2236A do.

On Sun, 07 Aug 2016 21:36:21 -0500, you wrote:

>A slight correction to a typo in the description below (sorry for the
>long delay). The correct Tektronix model numbers of these counters start
>with DC (not TM).
>The Tektronix TM500 (manual control) and TM5000 (GPIB or manual control)
>instruments which used the National Semiconductor MM5837 noise generator
>chip were the following:
>These models were manufactured from the early 1980's until 1995.
>The first two digits of the instrument model number designated the type
>of instrument. So:
>DC = Digital Counter
>DM = Digital Multimeter
>SG = Signal Generator
>PG = Pulse Generator
>AA = Audio Analyzer
>PS = Power Supply
>TM = Test Mainframe (which includes the power supply for the plug-
>in modules)
>Typically the 10 MHz internal standard or proportional oven timebase
>(or external 1/5/10 MHz rear edge connector timebase input) is dived
>down with 7490 TTL /5 and /2 divider sections to 1 MHz. The 1 MHz
>reference then drives a X100 PLL (using an ECL oscillator with varicap
>frequency control and 4044 phase detector) to create the 100 MHz main
>internal clock. The MM5837 pseudo-random noise generator phase
>modulates the PLL in some instrument modes of operation so that time
>interval averaging works correctly if the input signal is synchronously
>related to the clock.

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