[time-nuts] was there ever a "conclusion" on distribution amps ?

Bob Camp lists at rtty.us
Wed Feb 23 18:03:23 UTC 2011


Hi

That would be the "video amp" alternative. Works fine at some level. I don't
have one so I'm only guessing that it's in the 2x10^-11 at 1 second range. I
would be very surprised if it's not though. 

Is that good enough for the gear you have? I certainly have not seen much
stuff that would be unhappy with a standard at that level. This being Time
Nuts, you do have to ask.... 

One other area that would limit you - if you are trying to multiply directly
up to microwave off of the 10 MHz, then that's a special case as well. 

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Pete Lancashire
Sent: Wednesday, February 23, 2011 12:52 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] was there ever a "conclusion" on distribution amps
?

was thinking along the lines of this (now discontinued)

http://www.tapr.org/kits_tadd-1.html



On Wed, Feb 23, 2011 at 8:51 AM, Bob Camp <lists at rtty.us> wrote:
> Hi
>
> How good a 10 MHz do you need noise wise?
>
> If the stuff is common lab gear, there are a bunch of ways to go. If you
are
> driving dual mixer setups then your choices narrow down a bit. Having
stuff
> on one bench (and ground) is easier than running cables hundreds of feet.
>
> Assuming it's normal lab gear on one bench:
>
> Sixteen port power splitters from a junk pile should have about 12 db of
> loss. Run about 100 mw / 20 dbm into it and you will have plenty of signal
> to run normal lab gear. An ACMOS hex (or octal) buffer based amp can give
> you that sort of power. Having the logic levels also helps get to 1 and 5
> MHz. Not a lot of isolation, not real low noise, plenty good enough for 1
to
> 2x10^-11 at one second.
>
> A few alternatives are also pretty easy. Use a single logic to sine amp
per
> output and drop the power splitter. Run video amp chips and forget about
the
> logic conversion. For better performance, run discrete 2N3904(6) based
amps
> for each channel. A lot depends on what you already have lying around.
>
> If it's not the garden variety stuff, then indeed you likely will need
> something a bit more complex. I'd still consider a simple system to drive
> the easy stuff and only go fancy for the one or two things that really
need
> something that's low noise / high isolation / what ever.
>
> If you also are trying to do RF work (like HF radio) consider the spray
from
> what ever you do. I have seen 10 MHz standard setups that put out massive
> signals at 30 or 50 MHz. A bit of thought, a solid ground sheet, and some
> cheap coils / caps can go a long way.
>
> Bob
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Pete Lancashire
> Sent: Wednesday, February 23, 2011 11:18 AM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] was there ever a "conclusion" on distribution amps ?
>
> I will soon have my 11 th piece of equipment that I want to feed 10
> MHz (and some oldies 5 and 1).
>
> What is the current though on making one's own distribution box ?
>
> -pete
>
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