[time-nuts] LTE-Lite Plans

[Jim Sanford]

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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