[time-nuts] Call for input and beta testers -- Simple DistributionAmp/1pps divider

John Miles jmiles at pop.net
Fri Jun 3 17:07:10 EDT 2005

Hi, John --

I'd be potentially interested in the beta program, as I need to upgrade my
current 10 MHz rat's nest.  However... 4 ports are nowhere near enough, and
I think quite a few people will agree with me there.

Right now, my Thunderbolt drives an HP 5345A, HP 5370B, HP 8656A, Tek
492(4)AP, a homebrew synthesizer, a VHF/UHF receiver, and a loose coax cable
to drive whatever is on the workbench at the moment.  That's 7 applications,
and if I had another port, I could probably find a use for it.  Currently I
make do with a 4-way CATV splitter and a couple of BNC tees.

Output level needs to be at least +10 dBm into 50 ohms for the benefit of
some of the pickier "clients" like the 5345A... and not more than about 3V
peak into an open circuit (aka about +20 dBm into 50 ohms).

I (personally) don't have a use for 1 pps, so that feature would probably go

Houses should come pre-wired for 110V, 220V, CATV, RJ45, Cat6, and 10 MHz!

-- 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: Friday, June 03, 2005 1:41 PM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] Call for input and beta testers -- Simple
> DistributionAmp/1pps divider
> Hi All --
> I'm working on a new project for TAPR that some of you may be interested
> in, and I'm soliciting your input, as well as three or four of you to be
> beta testers.
> By way of background, TAPR (http://www.tapr.org) is an international ham
> radio organization that supports advanced R&D work in ham radio.  For
> the last several years, I've been its President (i.e., chief cook and
> bottle washer).  Although TAPR started by developing hardware for packet
> radio, we've been involved in time and frequency stuff as well.  We
> supported the development of, and marketed, the "TAC" (GPS interface
> board) that's used all over the world in GPS timing systems, and we're
> about to introduce the Reflock II, a PLL system designed to lock an
> oscillator of virtually any frequency to a frequency reference or
> GPS input.
> I'm just about finished designing my first TAPR project, and it's one I
> think this crowd might find useful.
> It's a combination distribution amplifier and 1pps divider built on a
> single circuit board.  The key features are:
> *  Broadband amplifier (from near-DC up to about 30MHz, with usable
> response out well beyond that.  There will be an optional bandpass
> filter to reduce spurs from, e.g., a square wave input.
> *  50 ohm or high-Z input, with 4 buffered and isolated 50 ohm outputs.
> *  PIC-based divider that can generate 1pps output from 100kHz, 1MHz,
> 5MHz, or 10MHz inputs.  It has a synch input to for setting against an
> external pulse, and provides two low-Z outputs.  (The code is based
> heavily on the design that TVB published, and is used with his
> permission.)
> I have some specific questions about the feature set that I'd like to
> ask potential users, and I would also like to find three or four people
> willing to build beta versions of the kit (it's through-hole technology
> and assembly should be fairly straight-forward, but will require basic
> electronic assembly skills).  Beta testers will be asked to pay the cost
> of parts, and can keep the beta unit when testing is finished.
> Our hope is to have the beta kits available within six to eight weeks.
> We'd like anyone buying a beta kit to commit to building it within a
> month after receipt.
> If you're interested in providing design input, or being a beta tester,
> please contact me off-line.  I'll be setting up a separate mailing list
> to handle the discussion.
> Thanks!
> John
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