Re: Slowman is a LIAR, was OT: Why welfare doesn't work!


bill.sloman@xxxxxxxx wrote:

On Sep 15, 2:06 pm, "Michael A. Terrell" <mike.terr...@xxxxxxxxxxxxx>
wrote:
bill.slo...@xxxxxxxx wrote:

On Sep 14, 5:21 pm, "Michael A. Terrell" <mike.terr...@xxxxxxxxxxxxx>
wrote:
bill.slo...@xxxxxxxx wrote:

I don't have a clue about his circuit designs - for all I know the
defects of the MC4024 and the MC4044 which I did use (once) were all
forced on him by the limitations of the Motorola process technolgy of
the time. I've been much happier with more recent Motorola parts,
which does suggest that Jim might have been less competent than his
successors.

You are the only one I've ever head complain abut these simple phase
detectors. I have seen them in a lot of commercial & industrial
products. Commodore used the MC4044 in over seven million C64 computers.
If it was as bad as you claim, they could have never shipped that many
working computers.

The MC4046 put the phase detectors from the MC4044 and a much VCO that
the MC4024 offered in a single package. It took years before the
Philips 74HCT9046

http://www.nxp.com/acrobat_download/datasheets/74HCT9046A_5.pdf

fixed the bug in one of the phase-detectors (see Fig 8 on page 8).

I'm not saying that the parts couldn't be made to perform - I got them
to do what I need them to do - but they were clumsy and awkward.
Quite a lot of that obviously came from Jim having built the parts
with a TTL process - CMOS supports the application a lot better - but
my impression at the time was that they could have been made easier to
use, even within the limitations of a bipolar process.

I have been aware of the 4046 and 9046 CMOS chips for years, Bill.
The built in VCO is worthless, when you are working around 500 MHz.

The built-in VCO in the 4046 won't do 500MHz


Isn't that exactly what i said in the line above yours?


http://www.standardics.nxp.com/products/hef/data***/hef4046b.pdf

doesn't guarantee more than 500kHz at 5V and while 74HC40406 parts do
a lot better with the

http://www.fairchildsemi.com/ds/MM/MM74HC4046.pdf

guaranteeing 7MHz at 4.5V but this is of little relevance in your
application where you were presumably locking your 500MHz (or so) to a
high quality 10MHz crysal-based reference oscillator.


It was divided down to 100kHz and the VCO was divided into four
overlapping bands to reduce phase noise, and liniearity. The total range
was over 120 MHz, centered near 500 MHz.


We used an ECL prescaler, followed by programmable counters.

So why didn't the designers replicate the internal logic of the MC4044
in ECL to get even better performance. Not that it is something a
technician would think of doing, of course.


The orginal phase detector was ECL, but the MC4044 worked better. it
had less of the reference bleed through, and was eaiser to filter from
the VCO's tuning voltage.


In my stroboscopic electron beam tester we were locking 800MHz to a
50MHz crystal-based reference, and used a rather neat ECL-compatible
detector chip that Analog Devices were selling at that time (1988).


They tested what was availible, and stareted with a now obsolete ECL
chip, then changed to the MC4044 when it worked better in the same
design.

--
Bill Sloman, Nijmegen


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