Margina design? ;) Better said, very poor design.
Does not sound very good that same part, same lot code, sometimes work
here but not there, sometimes does not work at all... Extending it a
bit... sometimes will work at a given temperature, sometimes will not at
a given other.
Regards,
Javier
Robert Atkinson escribió:
The old King Radio (then Bendix-King now part of Honeywell) Silver crown aircraft radios used 4046's in some of the synthesisers. The one in the VHF com had a different King part number to that in the ADF (MF direction finder). While trouble shooting we tried an ADF chip in a VHF (didn't have the VHF part in stock). It sort of worked but was slow to lock-up at the ends of the frequency range. Ordered some of the correct parts, both ADF and VHF. They all had the same manufacturer's part number and date code but different King numbers overstamped. Appaently the selected then at the factory for low noise (ADF) or wide pull-in (VHF).
Robert G8RPI.
--- On Sun, 27/9/09, Joe McElvenney <[email protected]> wrote:
From: Joe McElvenney <[email protected]>
Subject: [time-nuts] Egg on Face (was EPE - GPS Frequency Reference Project)
To: "Time Nuts Digest" <[email protected]>
Date: Sunday, 27 September, 2009, 11:00 AM
Hi,
There's a subtle difference between 3rd phase detectors
in the 74HC4046A
(Philips/NXP, ON, TI) and the 74HC4046 (Fairchild, NS)
The 3rd Phase detector in the 74HC4046A works as the
designer intended
in the GPSDO circuit, the 3rd phase detector in the
74HC4046 does not.
The 74HC4046 uses an RS flipflop for the 3rd phase
detector and requires
narrow pulses on the R and S inputs.
The 74HC4046A uses extra internal gates to ensure that
only narrow
pulses are seen by the RS flipflop in the 3rd phase
detector.
Bruce
You are perfectly correct. I hadn't noticed that there was
a 74HC4046A
fitted to the board in the article but just a plain
74HC4046 shown in
the parts list. However, it is something to watch out for
as this will
be a popular project among those, like myself, who do not
need to slice
time quite so finely.
Cheers - Joe G3LLV
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--
------------------------------------------------------------------------
Javier Herrero EMAIL: [email protected]
HV Sistemas S.L. PHONE: +34 949 336 806
Los Charcones, 17A FAX: +34 949 336 792
19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com
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