[time-nuts] Trimble TB replacement options???

Bob Camp lists at rtty.us
Sat Oct 12 15:32:14 EDT 2013


Hi

Lady Heather is a very Trimble specific program. It's not going to by a lot of help with a non-trimble based design.

LH (as I've mentioned before) really does not calculate a proper ADEV. Not because it's broke, but because it can't without a very stable "third oscillator" to compare to.

Bob

On Oct 12, 2013, at 3:22 PM, Don Lewis <dlewis6767 at austin.rr.com> wrote:

> 
> I just completed my second scratch GPSDO and would like to share a few of
> its details and ask a question or two at the end)
> 
> 
> 
> I think the point of the below is that it did not cost very much, either
> time or money.   It was very easily designed and built.   I think the
> GPS-locked 10MHz output frequency is pretty good .but need to better
> understand how to use (Lady Heather?) to calculate ADEVs.
> 
> 
> 
> 
> 
> I started with a couple of HP part-donor units that came my way from eBay.
> (TRULY part units -like they were missing entire pwbs and cables and such
> ...no way to easily rebuild ...but that is another story...)
> 
> 
> 
> 1.    I first built up my own discrete power supplies, needing +5VDC;
> +16VAC, and -18VDC using transformer wall warts (no switchers).   I used the
> some of the large blue filter caps from the donor HP units to help DC
> filtering.
> 
> 2.    I took an older HP10811 oscillator and its controller-board from a
> donor unit and fed the 10MHz output to an oscillator card I had from a donor
> 3585A spec analyzer (A21).
> 
> 3.    I wrapped the 10811 oscillator in several layers of cork I had around
> the house; and attached a small digital thermometer sensor to the outside of
> the oscillator, prior to wrapping.  It seems to maintain a constant 100F
> with little effort or regard to room temperature.
> 
> 4.    The standalone 3585A, A21 board takes the 10MHz from the 10811
> oscillator and locks it to its own, discrete, on-board 90MHz oscillator on
> the A21 board.  Then it nicely divides this 90MHz down several times
> (frequencies the 3585A spec analyzer originally needed).
> 
> 5.    I get outputs from the A21 board:  90MHz, 10MHz, and100KHz.  (lots of
> ECL on this little A21 board)
> 
> 6.    I then added my own simple divide by 10 to take the 100 KHz to 10 KHz.
> 
> 7.    I used an (eBay) NAVMAN-Motorola GPS unit that has a 10 KHz output to
> feed an XO; this XO feeds a few RC discretes that develop the analog EFC
> back to the HP10811 oscillator.  (Adjusting the 10811 oscillator to such an
> initial frequency that allows the lock EFC voltage to be positive is
> necessary.
> 
> 8.    Letting all this run overnight is showing the HP1011, 10MHz oscillator
> locked to GPS that has a TI of 100ns with all zeros to the right of the
> decimal point, . out to decimal places eight & nine on my good 5370B TIC,
> .(decimal places eight and nine fluctuating around +- 20)
> 
> 
> 
> Btw .I use my first GPSDO (similar, with NAVMAN/Motorola, but no fancy A21
> board .etc) .as the 10 MHz external reference to the 5370B TIC.
> 
> 
> 
> Question, please, how do I get this GPSDO (input) into Lady Heather?   I do
> have an RS232 interface into my computer for the NAVMAN, and can monitor the
> GPS with a simple GPS monitor program.but this is not the locked,
> disciplined frequency from the 10MHz HP10811.
> 
> 
> 
> With my setup .how does one compute the ADEVs?
> 
> 
> 
> -Don Lewis
> 
> Austin, TX (Hyde Park)
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
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