Hi I think you will find that the SYPD-1 (or RPD-1) is the better choice compared to the SRA-1.
Are the schematics out there for the curious to look at? Thanks! Bob On Jan 25, 2010, at 7:01 AM, [email protected] wrote: > Allow me to add some comments to this subject. > Five month ago I set out to make a DMTD that would be $ 200 max and be such > that any one can build it with readily available parts. The unit also > includes five counters yielding a resolution of 1 E-15. Using five counters > not > only gives Allan Variance but also frequency difference. The counter is > powered by the computer through USB and also transfers the data to the PC. > The counter section is less than $30 of the total cost. The cost goal has > been reached. The counter does not have to be used if one wants to use his > present counter. The DM board does have high speed opto couplers that allow > other counters. Corby is presently using that approach. Cost does not > include > the offset Osc. but a low cost solution is in the works, subject to > evaluation. > Corby Dawson and Richard McCorkle have been major contributors. > The goal is 1 E-13 and present tests show 3 E-13 right out of the box. > Having Cesiums, Rubidiums and Xtal Osc. the best I have is a FTS 1000 > A-100 with 3.11 E-13 at one second. I also think I will never have any thing > better than the FTS unit. That is why my goal is 1 E-13. > The present unit uses SYPD-1 as mixers but Corby will test the unit with a > couple of HP10514A's to evaluate the Mixer contribution. > I realize I am offending some of the purists on this site but I wanted to > keep cost down so I squeezed both channels on a very compact board > (4.3X2.9) and the counter is on a 4.3X2.3 board. How ever if we will not > reach 1 > E-13 with this approach I have a fallback using individual boards for each > channel still meeting the cost goal. Other Mixers will also be evaluated, > like the SRA1 since price and availability of the HP10514A/B will not help > the > cost goal. > 1 E-13 should satisfy 95% of time-nuts and at $200 including PC boards. > The second board with some changes hopefully will be assembled this week for > testing and based on its results a third board will go to ExpressPCB. > It is moving slower than what I had hoped for, but 3 E-13 right out of the > box with no special magnetic shielding or power supply decoupling gives me > hope. > PC boards will be the major cost factor, for my calculations I assume in my > calculations that ten boards will be ordered at a time. > > Bert Kehren Miami > _______________________________________________ > 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. > _______________________________________________ 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.
