JDSU (VIAVI) JD-745B with an RL measure problem?

[aspisys]

Hello

I own a JDSU (VIAVI) JD-745B that I think I might have found a design flaw of them...
Working with it for many years, never had (seen) a problem with it, until last month when I wanted to tune a cavity BPF for the FM broadcasting band. This one needed to be set for CF at 103.7MHz and while doing an RL measuring setting on it I noticed a weird display reading on my JD745B ! There was a 'sweep hole" visible as being centered to 103.5MHz! The RF generator circuit seems to stop working whenever frequency sweeps the 103.5 +/- ~50KHz spot! I did some test to confirm this "flaw" by feeding the RF Out of the 745 to an HP 8566 SA and using peak hold on it I confirmed that the 745s RF Out stopped every time passing thru that specific frequency, the 103.5MHz.


I contacted the seller of it, that I had bought it many years ago, and he replied to me that he had also been informed for this exact sweeping frequency problem from at least another user, but since he doesn;t know what this could be, he believes is a design flaw/bug/errata only of those specific models/make. That is because he did test some Gencomm GC747A that are almost same, and those didn't appear to have that problem, at least not at this frequemcy spot, according to him!

Anyone else has ever seen that flaw? Anyone that have worked with the insides of the JD 745's and might have some suggestions where this might be coming from?

Regards
Sotris