From: "Daniel Sheen" <danielsheen5@...>

To: [email protected]

Sent: 4/13/2020 5:59:33 AM

Subject: Re: [HP-Agilent-Keysight-equipment] 5343A troubles

?

Thanks for all the replies,

?

further poking hasn't revealed much yet, though I haven't completely ruled out the front end connector yet (seems solid though). Power supplies seem ok.

?

I'm slightly suspicious of the sampler driver at this point. It occurs to me that if somehow that were damaged in a way that suppressed even harmonics (idk how that could occur yet though) this seems like the symptoms that I'd expect to see.

?

Further troubleshooting of that is on hold while I fix my 8555A, which apparently decided now was the perfect time to lose its +10V and +20V power supply:( But once that's fixed I'll come back to this.

?

Best,

Daniel

?

?

From: <[email protected]> on behalf of Askild <megafluffy@...>
Reply-To: <[email protected]>
Date: Friday, April 10, 2020 at 6:07 PM
To: <[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] 5343A troubles

?

Hi Daniel,

?

Check the power lines for ripple.

I have a HP 5351B dumpster find, that did not work to well, needed higher input level, and did not work on all frequencies...

It was missing one of the capacitors in the power supply, so lots of ripple.

After finding the missing cap, and putting in a new one, it behaved great.

?

Might not be your issue, but its an easy check..

?

BR,

Askild

?

?

On Fri, Apr 10, 2020 at 7:49 PM Daniel Sheen <danielsheen5@...> wrote:

Hi all,

?

I have a rather bizarre problem with a 5343A counter. Observed symptoms are that the high frequency input works reliably up to about 250MHz, reads garbage from around 250MHz-800MHz, and then seems to work fine from 800MHz upward through 1GHz (I only have an 8640B handy atm so can't really test higher than that). Cranking up the input power a bunch seems to reduce the dead band to closer to 400MHz-600MHz.

?

The counter initially failed troubleshooting step 4 in the service manual. That was resolved by replacing the A10 board (from another counter with a blown sampler). It now passes step 5 and is marginal on step 6 (sensitivity is a little lower than it ought to be but it seems to work).

?

The one other observation I've made is the IF amplitude into and out of A11 drops off rapidly if an input is tuned into the range of frequencies that it's insensitive to, but I'm struggling to find a plausible explanation for why that could occur given my understanding of the counter design (that wouldn't also make higher frequencies not be detected).

?

If anyone has any thoughts or has run into this before, suggestions would be appreciated.

?

Thanks,

Daniel, KC1EPN