Max Skop wrote: > Hi Samuel and all, > Welcome to the group. > I also have a 53131A and would welcome any way to enhance or upgrade the > performance of this instrument. Please count me in on clone option parts. > As can be seen from the picure of the 3Ghz option there is nothing special > in its construction. Just four stages of amplification and a divider.
In 1987, I was the project manager for the HP 5334B frequency counter. In those days, we had a 1.3 GHz option called a "C channel". I evaluated various off the shelf dividers at the time and built some C channel boards very similar to the one you are describing. It is actually very difficult to make a prescaler that really works well using off the shelf dividers. The prescaler tends to be insensitive to low frequencies. Attempting to fix this with a lot of gain (4 stages!) has the problem that any wideband noise from the source is also amplified. Off the shelf dividers are made to work in frequency synthesizers where they have a clean signal from an oscillator. They don't do well with general signals from noisy sources. The HP 5386 used an HP made frequency divider that had "static" flip flops instead of the "dynamic" ones in all the off the shelf dividers. It is the only prescaler I am familiar with that actually works well. The custom IC in it cost HP a fair amount just because it was "home made" in the Santa Rosa fab, which was a money sink. If you want to build your own prescaler, you might not want to copy the Agilent one. Unless you need the sensitivity, you would be better off with less gain. Also, you should choose a divider that works well at the frequency you want to measure. AFAIK, all OTS dividers have an optimum frequency range, which varies from divider to divider. When testing prescalers, the thing to watch out for is that the lower order digits will bounce around. This is usually a symptom of prescaler error, assuming that the source is stable. Rick Karlquist N6RK _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
