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

[John Miles]

Having done some early prototype testing on this upcoming amplifier (no
financial involvement) I'll suggest that it may be worth waiting for.  The
isolation at 10 MHz is better than 90 dB, the PN floor is better than -170
dBc/Hz, and the cost will -- as usual for TAPR -- be much less than what
other vendors charge for similar specs.

It's also easy to adjust the gain on these amp modules.  They are meant for
both distribution and single-channel isolation amp service, as John says.
This is a potential advantage versus standalone splitters, which have a very
limited fanout due to loss, and random video amps, which may have too much
or too little gain to make up for the loss in the splitter.

-- john, KE5FX


> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of John Ackermann N8UR
> Sent: Wednesday, February 23, 2011 10:58 AM
> To: Discussion of precise time and frequency measurement
> Cc: Pete Lancashire
> Subject: Re: [time-nuts] was there ever a "conclusion" on distribution
> amps ?
>
>
> All --
>
> I hesitate to make pre-announcements, but TAPR plans to produce a very
> high performance replacement for the TADD-1, as well as a single-channel
> version for buffer/isolation amp use.
>
> I'm just on the verge of ordering alpha boards for the single channel
> version.  I really can't hazard a guess as to availability dates yet,
> but we'll make a more specific announcement when we have a better
> picture of the road ahead.
>
> John
> ----
>
> On 2/23/2011 12:52 PM, Pete Lancashire wrote:
> > 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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