[time-nuts] LTE-Lite Plans

Said Jackson saidjack at aol.com
Wed Nov 26 17:38:42 UTC 2014


Jim,

A double tragedy. I was working with Jim Williams on one of our designs a week before he passed away. Then Bob crashed his car coming from Jim's funeral (grief?) and died too.

Two of the greatest analog minds lost within days.

Bye,
Said

Sent From iPhone

> On Nov 26, 2014, at 9:34, Jim Sanford <wb4gcs at wb4gcs.org> wrote:
> 
> Interesting comment. . . . I'm reading Bob's book now!
> Never met him, but felt like I knew him from all of his writings.
> 
> His death was very sad....
> 
> Jim
> wb4gcs at amsat.org
> 
>> On 11/26/2014 12:20 PM, Didier Juges wrote:
>> Said,
>> 
>> Your drawing looks better than those byBob Pease,  and he was never
>> embarrassed by his :)
>> Thank you for your extensive contributions to time nuts
>> 
>> Didier KO4BB
>> 
>> 
>> On Tue, Nov 25, 2014 at 7:28 PM, S. Jackson via time-nuts <
>> time-nuts at febo.com> wrote:
>> 
>>> Guys,
>>> 
>>> I never expected such an intense discussion about using and buffering  the
>>> outputs from the LTE-Lite board since the actual circuit to use can  be
>>> quite simple.
>>> 
>>> To address these questions, I drew up a simple schematic that uses a DIP-14
>>>  74AC04 gate, six resistors, and two caps. Everyone who can solder should
>>> be able  to build this simple circuit as a dead-bug type build on a
>>> copper-clad  board.
>>> 
>>> This circuit will buffer all three outputs (1PPS, TCXO RF, and Synthesixed
>>> RF) of the LTE-Lite eval board with CMOS 3.0V levels that can drive 50 Ohms
>>>  terminations. For simplicity I grab the 3.0V power from the DIP-14 TCXO on
>>> pin  14 of that part on the eval board, even though I would strongly
>>> suggest to use a  separate low noise 3.3V or 5V power supply to power the
>>> 74AC04
>>> chip.
>>> 
>>> You can add 100nF caps in series to the two RF signals before they feed
>>> into the coax output connectors for less power consumption and removing DC
>>> for
>>>  instruments that don't like DC inputs.
>>> 
>>> Using a single IC for the three signals will result in crosstalk between
>>> the signals, but it should be clear from the schematics how one could break
>>> up the signals by using three independent ICs to minimize crosstalk.
>>> 
>>> We use this circuit in a small box here using SMT components, and it works
>>> really well.
>>> 
>>> Excuse my horrible writing, using keyboards has made my fingers  numb..
>>> 
>>> Hope that helps,
>>> Said
>>> 
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> 
> 
> 
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