Hi …. a very normal way to get to 10 GHz is to lock up a low noise VHF oscillator as a “cleanup” device. This is true even with a very good 10 MHz source. The 20 log N stuff simply beats you up to much.
Some math: A really good 10 MHz source might be in the -170 dbc/ Hz range far removed from carrier. That gets to -150 with an ideal multiplication to 100 MHz. Any more “normal” source will be worse than that 10 MHz OCXO. The 100 MHz will be even worse as a result. If your source is in the -140 to -150 range, the output will be -120 to -130 dbc/ Hz. For not a lot of money, you can get small VCXO’s at VHF with pretty good noise numbers. A part that hits -160 dbc / Hz at 10 KHz offset is not all that unusual. That will give you a *lot* of noise reduction vs that -120 to -130 dbc/Hz. By the time you get to 10 GHz, you add another 40 db to the 100 MHz numbers. -120 goes to -80 dbc/ Hz. That’s a lot of noise …. Bob > On Mar 29, 2021, at 1:14 PM, John Ackermann N8UR <j...@febo.com> wrote: > > That's probably a really bad idea. The phase noise from the TIMEPULSE output > is pretty bad compared to a "real" RF source, and by the time it's multiplied > up to 10 GHz you'll have more noise than signal. Attached are some phase > noise plots and a couple of spectrum analyzer captures to give you some idea > what to expect. > > BTW, even the Bodnar unit may not look too good at 10 GHz -- remember that > you increase phase noise by 20 dB for 10 times multiplication. > > John > > > On 3/29/21 12:25 PM, Chris Wilson wrote: >> 29/03/2021 17:20 >> Can I use my Ublox NEO-M8T-0-10 as a LO for a modified satellite LNB on >> 10 GHz? It needs 25 MHz and the Ublox is my only GPS locked source for such >> a frequency. I want to receive the Es Hail downlink with excellent >> stability. I can lock the receiver to 10 MHz which is available from my >> Trimble Thunderbolt. If the Ublox would do I would not have to buy something >> like the Leo Bodnar GPS. Thanks. > <zed-f9t_hp8642a_narrow_inverted.gif><zed-f9t_hp8642a_wide_inverted.gif><uBlox_10MHz_pn.png>_______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
