[time-nuts] Any reason not to use one power amplifier and splitter for distribution amplifier?
actast at hotmail.com
Mon Jan 5 23:15:21 EST 2015
Good point Bob, in my humble opinion "Low Noise" is about -115 @ 1 Hz dropping to about -165 @ 10KHz for 5 MHz about 3dB higher for 10MHz. Which from my testing will tax the noise floors of a fair number of application specific products.
It is true that most of these distribution amps sold today were designed at least a decade ago, so there may be chips today that can meet or exceed those products on paper for DIY projects but it will still be a challenge for most of us. Thanks for your input
> From: kb8tq at n1k.org
> Date: Mon, 5 Jan 2015 19:59:39 -0500
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] Any reason not to use one power amplifier and splitter for distribution amplifier?
> Any time you run into terms like “low noise” it pays to think about what that means to you and your system. A quick scan of the posts here over the years will show that different definitions of low noise do exist. The same is true of system requirements. An offset that matters to one may have no impact at all on another system.
> In some cases -155 dbc/Hz at 10KHz or 100 KHz is “low noise”. In other cases “low noise” is -180 dbc/Hz. In either case, *delivering* a clean signal without spurs and crud is far from simple. In many long cable run cases, the cost of fancy cables, high performance magnetics, and all the other “stuff” is more than the cost of simply locking up a quiet oscillator on the end of a “dirty” cable. I don’t think I’ve ever seen a setup that tries / needs to “distribute” < -170 dbc/Hz signals over anything bigger than a rack. I’ve seen *lots* of systems that regenerate those sort of signals many times over (= in many different boxes) to get around distributing them.
> > On Jan 5, 2015, at 2:15 PM, Tom Knox <actast at hotmail.com> wrote:
> > Happy New Years All! I have seen a number of discussions on various approaches to distribution amps discussed on Time-Nuts ranging from DYI to products intended for Video.
> > I thought I my weigh in with one point of interest; It seems like long term performance is pretty easy, but a low phase noise solution is quite a different story. Looking at the number of application specific products from MicroSemi/Symmetricom and other manufactures claimed and even more so real world specs vary a great deal so apparently it s not easy to just throw something together with great or even good close in phase noise. So depending on your labs direction in the future it may be worth researching and investing in an application specific distribution amp. I like the MicroSemi 4036B but there are a number of very good products out there on the surplus market selling for a small fraction of their original cost.
> > Cheers;
> > Thomas Knox
> >> From: bill.riches at verizon.net
> >> To: time-nuts at febo.com
> >> Date: Sun, 4 Jan 2015 08:29:34 -0500
> >> Subject: Re: [time-nuts] Any reason not to use one power amplifier and splitter for distribution amplifier?
> >> A cheap and dirty equivalent of a pass thru terminator that I use is a BNC t
> >> connector with a 52 ohm bnc terminator. I guess you could use a CATV 75 ohm
> >> F type with an adapter. Maybe that combination would produce too much
> >> garbage.
> >> 73,
> >> Bill, WA2DVU
> >> Cape May
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