James R. Gorr said the following on 02/18/2008 12:18 PM: > I have a Spectracom 8140 frequency distribution amp. > I see on ebay there are line taps for this device. Do > I need the line taps? Or can I just use the 8140 as > is? What are the line taps supposed to do?
I use the 8140T line taps without an 8140 unit. All they require is a +12V DC signal riding along with the 10 MHz sine wave. You can string a bunch of taps off one reasonably strong source. I have an HP 5065A Rb that I slightly modified to tap the 10 MHz off from the internal 10811A oscillator before the divide-by-2 circuit*, and putting a 12 volt DC bias on the signal (with an isolating capacitor to protect the rest of the 5065A from the DC, of course). I feed about 10 of the 8140T taps from this line, and it works well. The 8140T amps have only decent phase noise performance; I wouldn't use one for a demanding application, but this string running around the lab makes it awfully convenient to grab a 10 MHz source wherever I need one. One thing -- you want to put a DC-isolated 50 ohm load at the end of the string to terminate the line. I believe the 8140 amp unit has a fault detector that will trip if it doesn't see that load, and it's good practice to properly terminate the line, anyway. John _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
