[time-nuts] Shera Controller - U7

J. L. Trantham jltran at att.net
Mon May 14 02:37:00 UTC 2012


I have always been interested in trying to improve the look of the 'dead
bug' style.  

How about a small PCB with an 8 pin DIP connector that is used to mount the
oscillator, the divide by 4 and get power, ground and provide 24 MHz and 6
MHz outputs to the 8 pin DIP.  That way, the 'little module' plugs into the
original socket on the PCB.  In addition, if the correct part ever becomes
available, it's just 'unplug and play'.

Lot's more effort but it sure would look good.  Might also allow for some
modifications to raise the 24 MHz and achieve smaller phase increment
corrections.

Likewise, a module could be built to plug into U2 to provide for a 10 MHz
VCXO and with jumpers for whatever frequency VCXO you might choose.  As
designed, the controller is good to 5 MHz or so.

Come to think about it, is it time to think about a 21'st century Shera
Controller re-design?  Or has the TBolt made that obsolete?

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of shalimr9 at gmail.com
Sent: Sunday, May 13, 2012 9:08 PM
To: kevin.staley at virgin.net; Time-Nuts
Subject: Re: [time-nuts] Shera Controller - U7

A 74AC74 in SO-14 package mounted dead bug style will make a handy /4 that
is no bigger than most crystal oscillators.

If that's still too big, you can go with the TSSOP, but no coffee for you
for a week prior to soldering that baby :)

Didier KO4BB

Sent from my BlackBerry Wireless thingy while I do other things...

-----Original Message-----
From: "Kevin Staley" <kevin.staley at virgin.net>
Sender: time-nuts-bounces at febo.com
Date: Sun, 13 May 2012 17:27:20 
To: 'Discussion of precise time and frequency
measurement'<time-nuts at febo.com>
Reply-To: kevin.staley at virgin.net,
	Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Subject: Re: [time-nuts] Shera Controller - U7

Hi all
Thanks for the many responses.
It would seem that U7 is pretty rare.
I think I will be going with a 24 MHz "Can oscillator" and a separate 6MHz
source for the PIC either divided from the 24MHz oscillator or a separate
oscillator.

Thanks again
Kevin


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Chris Albertson
Sent: 13 May 2012 16:47
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Shera Controller - U7

On Sun, May 13, 2012 at 8:11 AM, J. L. Trantham <jltran at att.net> wrote:
> It is an 8 pin DIP, 24 MHz oscillator with an onboard divide output in 
> order to provide a dual output oscillator.  It is an ECS-300CX-240 and 
> DigiKey lists it as obsolete since 2009.  They say 'call'.

Sounds like a you could use a normal 24MHz TTL can oscillator and a dual
flip flop mounted "dead bug" style.

Chris Albertson
Redondo Beach, California

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