[time-nuts] Temperature and signal amp for 'Bay FE-5680A?

[Bob Camp]

Hi

A more ideal solution for the 5680 might be a little board with a 5V
regulator on it, and the 1 pps buffering. Hang it on the existing 9 pin
connector and have another (properly configured) 9 pin on the board for
RS-232 com. 

Pretty small board, pretty cheap parts. If you wanted the full blown
version, drop an LED on the lock output. 

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of David
Sent: Tuesday, January 10, 2012 10:19 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Temperature and signal amp for 'Bay FE-5680A?

On Tue, 10 Jan 2012 21:57:49 +1300, Bruce Griffiths
<bruce.griffiths at xtra.co.nz> wrote:

>Hal Murray wrote:
>>
>> The TADD-3 uses 3 AC drivers in parallel, each going through a 51 ohm
resistor.  Changing those resistors to 150 ohms should work.  Maybe a bit
lower to account for the impedance in the drivers.  I'd probably check it
with a scope.
>>    
>That approach doesn't do anything for the Vcc and GND bounce exhibited 
>by the driver chip.
>GND and Vcc bounce is the cause of the high frequency ringing exhibited 
>by the TADD-3 outputs.
>This ringing can even be observed at the outputs of inverters whose 
>inputs are tied low or high in the same package
>
>Damping the crossover current induced transient in the supply leads 
>(bondwire and lead frame) inductance is one way to minimise this.
>A small resistor in series with the Vcc pin often works well, the 
>resistor value being chosen for near critical damping.
>
>Another problem with the TADD-3 is the sharing of a driver chip by 
>different input frequencies which leads to intermodulation between the 2 
>outputs.

I have never seen that much ground bounce before so assumed it was a
termination problem.  Was the driver chip decoupling inadequate?  That
at least would be easy enough to fix.

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