tvb@LeapSecond.com said:

Thanks. My 301 says it is a 30TH Rev-A - mostly through hole parts.  Same
layout.

--
These are my opinions.  I hate spam.

On 03/30/2018 03:39 AM, Hal Murray wrote:

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

Hi John:

The U4226B chip operates at very high impedance levels in order to minimize battery drain in its main application,
battery powered clocks.
So some sort of buffer is needed on all the output pins.

The 333 model, with the analog meter, was made for the folks working for WWVB as a way for them to know the transmitter
was on the air.
http://www.prc68.com/I/timefreq.shtml#WWVBrcvr
http://www.prc68.com/I/Loop.shtml (WWVB)

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

-------- Original Message --------

Hi Brooke --

Yes, all the chips on the board are low power devices.  I'm measuring
the receiver as drawing 0.9 MA at about 2.3 volts.

Update -- I moved the receiver and farted around with the wiring, and
now the S-Meter is off the peg, responds to orientation changes, and I
actually got a couple of indications of bits being decoded.  So, I think
the hardware is working fine.

However, there must be a lot of local interference as decoding is very
erratic and I'm nowhere near getting a full sequence.  I don't have any
experience at this location with WWVB reception, so I'm not sure what to
expect.  At my previous Ohio house a mile south of here the signals were
very good and there were no noticeable problems with the Spectracom
receivers (may they rest in peace).  Next step is to experiment with
receiver placement.

John

On 03/30/2018 03:15 PM, Brooke Clarke wrote: