[time-nuts] 3.0GHz Channel 3 installation in Agilent 53132A counter
James Robbins
jsrobbins at earthlink.net
Wed Mar 19 15:26:39 UTC 2014
Thanks for everyone's help here. I have done some further sleuthing.
I have a second 53132A which has a 3.0GHz Channel 3. So, I switched the new channel 3 board into the old 53132A and it reads properly. Then, I switched the old 3.0GHz Channel 3 board into the new 53132A and it also read four times (4x) the input frequency. From this I conclude that the issue is with the new 53132A counter box and not the channel 3 board.
Then I powered up each counter and measured at the pins on the ribbon cable connector at the Channel 3 board to the main board on both the new and old counters (channel 3 boards plugged in and powered). They each read the same voltages and/or grounds (pin1 = 2v; 2,5,7,9,10 = ground; 3,8 = +12v; 4 = -12v with numbering based on "1" shown on channel board).
Someone suggested that maybe the new main board had been set up for the 12.5 or 6GHz channel 3 but was sold without that channel. The idea was that such a main board would cause a 4x reading. To my mind this is opposite to what I would think in that the division ratio for 12.5 or 6GHz would be higher than the ratio for the 3.0GHz board and would result in a fraction of the frequency rather than 4x frequency.
Of course, it could be a FW mod (rather than a HW mod) which has been applied also.
Any other thoughts are much appreciated.
73,
Jim Robbins
N1JR
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