[time-nuts] My stubborn Z3801A
Robert Benward
rbenward at verizon.net
Mon Jun 14 02:36:10 UTC 2010
The headers are in, that's why I though he completed the modification.
Bob
AC2AZ
----- Original Message -----
From: "Richard W. Solomon" <w1ksz at earthlink.net>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Sunday, June 13, 2010 8:43 PM
Subject: Re: [time-nuts] My stubborn Z3801A
> If you remove those "zero ohm" resistors, you need other jumpers
> to make it work as an RS-232.
> When I did mine, I stuck in two strips of "headers" and used those
> HD jumpers to select RS-232 or RS-422.
>
> Check out this site:
>
> http://www.ad6a.com/Z3801A.html
>
> 73, Dick, W1KSZ
>
>
> -----Original Message-----
>>From: Robert Benward <rbenward at verizon.net>
>>Sent: Jun 13, 2010 8:01 PM
>>To: time-nuts <time-nuts at febo.com>
>>Subject: [time-nuts] My stubborn Z3801A
>>
>>To All,
>>
>>An update to my Z3801A saga.
>>
>>Summary: As you know, I purchased this Z3801A at the Dayton Hamfest. The
>>person who sold it to me said it was modified for RS-232. I powered the
>>unit up and the only thing it ever did was go into the holdover mode. Tried
>>hooking RS-232, but got no response. Did some reading and found the little
>>green blinking light was a good thing, all the others indicated a failure in
>>ram, rom, etc. Boot was good if all the front panel lights went on in
>>sequence.
>>
>>Update: Took the unit apart to do some serious trouble shooting. Found the
>>signals (logic side) on the RS-232 did not go all the way to ground. Subbed
>>in another RS-232 transceiver, still no luck. Found another note on the
>>internet about removing the 5 little zero ohm resistors on the bottom to do
>>the RS-232 conversion. Looked on the bottom and they were still there!!! I
>>removed them and the signals now went all the way to ground and appeared to
>>be normal. Tried various programs to link up (GPS.EXE, SatStat, RS-232
>>comm). Saw the commands going in, and I did see a response from the Z3801A,
>>but the computer could not read the response. Since I did see a response
>>from the Z3801A on the scope, I figured it was receiving commands. I hooked
>>up an antenna and sent a survey command. Apparently if the GPS is moved (I
>>don't know how much) the Z3801A needs to do a survey otherwise it won't
>>lock. I went shopping, and came back about 2 hours later, and low and
>>behold, a GPS LOCK!!!
>>
>>Still to go: The RS-232 signals look fine going into the cable, +/-5V, any
>>ideas why the computer won't read it? Am I missing something? I tried two
>>different ports in case I screwed one up one of the ports, but no luck.
>>
>>Bob
>>AC2AZ
>>
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>
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