[time-nuts] 53132A counter slow frequency update
john_pease123 at yahoo.com
Thu Jun 30 00:06:25 UTC 2011
Thank you for the ideas.
I am using a Tektronix AFG 3102 DDS generator which works up to 100 MHz.
The counter firmware version is 3646.
I tried sine wave amplitudes between 70 mV and 1V ptp. The waveforms looked good on the oscilloscope. I did notice that the Hi-Z front panel input will attenuate the input signal quite a bit unless I terminate the rear panel inputs in 50 Ohms.
I tried different thresholds and gate times and I still get the same behavior.
If I flip between 100 MHz and 1MHz 20 times, there will be a delay in updating the 1 MHz measurement about 5 times.
I ran each of the self test routines and they all passed.
Both low frequency input channels show this behavior, as well as the 12.4 GHz input (input frequency switched between 12 GHz abnd 200 MHz).
A coworker suggested that the counter might be slower in updating to a new lower frequency because its interleaves counting edges and would be thrown off if the new edge rate was much slower.
The fact that your counter works as expected casts doubt on this possibility.
Any suggestions will be greatly appreciated.
Check your cable, or better yet, look at the input signal with a
oscilloscope. Something is fishy (missing return plus AC couple, too low
I used a 33250 generator at 50mVrms and tried going from 80MHz down to 1MHz,
even 100Hz and it changed the very next gate period every time (one period
had partial counts, of course).
The 53132A doesn't have the 'green button' that presets it to a known state,
but it always powers up in the default state.
Your signal might need some special handling - sensitivity, coupling,
Finally, if the counter is an 'eBay special', it might be bad. Run self-test
and follow confidence tests from service manual.
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of John Pease
Sent: Tuesday, June 28, 2011 11:07 AM
To: time-nuts at febo.com
Subject: [time-nuts] 53132A counter slow frequency update
My new to me counter has a strange response when I change the input
frequency. With the gate set to 1s, I can measure 100 MHz with plenty of
digits. Then I change the frequency to 1 MHz and it takes several seconds to
almost a minute for the display to change from 100 MHz to 1 MHz. The delay
only occurs when I lower the input frequency quite a bit; 100?MHz to 10 MHz
changes are displayed within 2 gate times.?When I increase the frequency
form 1 MHz to 100 MHz I always get the correct display after two gate times.
This delay is proportional to the gate time; the updating is 10 times faster
with 0.1 s gate time.
Is this behavior typical for this counter?
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