Karen To a large degree it depends on what you want to use it for. HP 5065 is considered top of the line and PRS 10 is a very nice Rb but lately I have seen lamp oscillator failures. I like FRK, well documented easy to modify and if done right super performance. As part of a GPSDO project using the FE 5680A that my Swiss friend Juerg and I have worked on for a year and is now in Beta test is also an alternative. We are done with FE 5680A so Juerg has his along with a GPSDO for sale. If you want a affordable Rb that has GPS control that is an alternative. Unit has less than 6 month running time so like new. Bert Kehren in Miami In a message dated 10/26/2014 2:01:17 P.M. Eastern Daylight Time, ra3apw@mail.ru writes: Hello All, Can I have your recommendation regarding a choice of 10 MHz rubidium source (available now on eBay like FE-5680; LPRO-101; LPFRS; FRS etc.) as a reference signal for my frequency counter Pendulum CNT-91. Thanks in advance. Karen, ra3apw --- Это сообщение свободно от вирусов и вредоносного ПО благодаря защите от вирусов avast! http://www.avast.com _______________________________________________ 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.