Hi Jack, You might want to rethink building that Elektor board, at least the way it is "out of the box". I took a good look at it and found that it uses a Cypress Semiconductor CY27EE16 PLL Clock Generator as a synthesized local oscillator. The CY27EE16 has a typical jitter specification of 250ps rms. This is pretty bad. By comparison, a good crystal oscillator should present less than 1ps rms jitter. To give you an idea how this translates to phase noise:
0.4psrms jitter (Isotemp OCXO134-10 10MHz VC-OCXO): 10Hz = -105 dBc/Hz 100Hz = -125 dBc/Hz 1000Hz = -140 dBc/Hz 230psrms jitter (for comparison): 10Hz = -50 dBc/Hz 100Hz = -70 dBc/Hz 1000Hz = -85 dBc/Hz Not only that, I get the feeling that the CY27EE16ZE may be set for deprecation. At least the Blueberry demo board for the part has been discontinued and replaced with a Peppermint demo board. The Peppermint demo board uses a CY22393 three PLL clock synthesizer part. The CY22393 has even worse specified jitter, a whopping 400psrms! But there are allusions in the data sheet that the jitter may be significantly less for some "settings", but it doesn't elaborate. I've just received a couple of Peppermint boards to test. Anyway, the seemingly poor choice of L.O. on the Elektor radio, along with the outrageously high price put me off. If you do build one of these, you might want to replace the CY27EE16ZE with an Si570. The Si570's jitter is specified at around 0.35psrms. Mike, KF4BQ has measured the phase noise of the CMOS version of Si570 to be -130dBc/Hz at 3-7kHz offset. His report is in the Files section. If you do replace the CY27EE16ZE with an Si570 (or something else), remember the G8JCF SDR software that accompanies the Elektor radio most likely will not be able to control the L.O. frequency. There's a group here for the G8JCF software with some discussion on the Elektor board as well - but not a lot of activity: http://groups.yahoo.com/group/G8JCFSDR/ 73's David (WB4ONA) --- In soft_radio@yahoogroups.com, "artus1947" <[EMAIL PROTECTED]> wrote: > > Hi folks, > > I wonder if anyone knows of any other sources for the Elector Boards -- > the shipping to the States (25 euros) is horrible. I tried etching the > boards myself, but I can't get a good registration between layers. > Thanks. > > 73, > Jack (W0FNQ) >
