Hi If you *need* to lock one of the new FE-5680's 10 or 20 Hz high, you probably can adjust the cap on the VCXO center it's range up there. I doubt it will reliably adjust out to 300 Hz though. For that parts changes or board surgery probably are required.
Bob -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of John Beale Sent: Thursday, January 26, 2012 1:29 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Things to look for when buying a few FE-5680A's? > On 1/22/2012 12:49 PM, Chris Albertson wrote: >> The current batch of (about) $40 units are different from what was >> available a year ago. These new ones require 5V DC input in addition >> to 15V and can only be programmed via RS232 a few Hz away from 10MHz. >> So they are only good for use as a 10MHz reference >> >> "Option 2" in the book refers to a different type FE5380 that can be >> programed over a very wide range of several MHz. I think these are >> still being sold on eBay but not for $40. They seem to be over $100. In the manual I have (see below) "Option 2" is in fact what I got for about $40. This is RS-232 control with very fine resolution, but limited range (10 MHz with a span of +/- 383 Hz according to the manual, although one I tested won't actually stay locked much above 1% of that span). The very wide range version is a different option, perhaps Option 08 (Customer specified frequency, 1 Hz - 20 MHz). ------------------- RUBIDIUM FREQUENCY STANDARD MODEL FE-5680A SERIES OPTION 2 http://www.wa6vhs.com/Test%20equipment/FREQUENCY%20STANDARDS/FE-5680A/5680%2 0TECH%20MANUAL.pdf Table 1: "Option Summary" [...] Option 02 Remote Digital Control - RS-232; Resolution: 1.8 x 10-7Hz "Frequency Adjustment" Section 2-3 The FE-5680A output frequency can be adjusted digitally over the RS-232 interface (pins 8 and 9). This feature is available as option 2, and is not available on units purchased without this option. The frequency can be adjusted with a resolution of 1.7854E-7 Hz. For an FE-5680A device with an output frequency of 10 MHz, this corresponds to a relative frequency setting resolution of 1.7854E-14. _______________________________________________ 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. _______________________________________________ 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.