[time-nuts] Ultralink

John Ackermann N8UR jra at febo.com
Fri Mar 30 09:40:43 EDT 2018


On 03/30/2018 03:39 AM, Hal Murray wrote:
> 
> tvb at LeapSecond.com said:
>> I updated http://leapsecond.com/museum/ulio/ with more manuals, and many
>> exterior / interior photos of the 301 module.
> 
> Thanks. My 301 says it is a 30TH Rev-A - mostly through hole parts.  Same
> layout.

Mine is the same.  Circuit is very simple.  The 20 pin IC is the U4226B 
receiver chip and it has two external 60 kHz filter resonators.  The 8 
pin DIP is a TLV2770C op amp which seems to be a buffer to drive the S 
meter from the very high impedance AGC test point on the receiver chip. 
And I am guessing that the 2N3904 transistor is a buffer for the time 
code output.

The modular cable connecting the receiver to the decoder is wired 
straight through, not reversed as most telephone cables are.  My fear is 
that someone (like me) might at one point have used a reverse cable and 
thus put reverse polarity on the board; I don't see any reverse power 
protection.

Later today I'll tap into the four conductors on the cable and see what 
signals I see on them, and also look for signs of life on the receiver chip.

BTW -- Donald Resor pointed me to UTSource which shows several Chinese 
vendors as having them in stock.  I get nervous about whether they are 
the real thing or not, but will probably order a couple just in case. 
The chip is a 20 pin TSSOP package, which isn't too hard to rework but 
before putting hot air on the receiver board there are one or two 
surrounding parts one would want to remove to avoid collateral damage.

John


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