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
wb4...@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@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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