[time-nuts] Temperature and signal amp for 'Bay FE-5680A?
Bob Camp
lists at rtty.us
Tue Jan 10 17:17:51 UTC 2012
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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