HP5335A Universal Counter - How to input B ?

[AllTheGearNoIdea]

https://www.keysight.com/en/pd-1000001399%3Aepsg%3Apro-pn-5335A/universal-counter-200-mhz?cc=GB&lc=eng

I have just finished repairing a HP5335, nothing worse than all the supply rails had failed.  The unit has 3 inputs A B and option C fitted.  Can someone tell me how to display the frequency for input B. I have read the manual and it mentions inputs A and C  but not B.    The B input does apper to be working and gating etc but there is no button to select B as the input.   Has anyone a memory of using these.

Looks like these units are quite poor by todays standards but I do like the nice big frequency display and I will probably run an external clock from my GPS disciplined standard. Anyone got a spare oven Osc option ?

Thanks

Chris

[Dr. Frank]

FREQ B is a 'Special Function', No 17,  either accessible by GPIB control via FN or FU command, or via front panel, described in paragraph 3-164 on page 3-21.
Press: SCALE, SMOOTH, 1, 7, ENTER

FREQ A is 200MHz, FREQ B is 100MHz only.

The 5335A is a very versatile counter, with a bundle of functions.
I really like it, with these many keys, and especially the numeric input, instead of these mediocre up/down keys on the successors, 53181/53131/53132A.

And it performs nearly as well, with its 10811 OCXO it's very precise, only the T.I. resolution is 1ns instead of 100ps.
So it displays 'real' 9 digits for 1sec gate time in frequency mode only, but that can be increased to 10 digits at 10s.. maybe to 11 digits at even longer Gate Time.
The modern counters are of the time stamping type, and do a continuous averaging, claiming 12digits per sec, but that's a  fake, as 100ps would yield 10 digits only. That also leads to problems with Allan ADEV statistics

Frank

[AllTheGearNoIdea]

Wow Many thanks that is a great reply.

Kind of strange they hid channel B via a special function menu ?   A front panel buttun would have made more sense for me since they have buttons for A and C

Chris