[time-nuts] Z3805 utility, Was: AW: (no subject)

Robert Benward rbenward at verizon.net
Sun May 23 05:05:39 UTC 2010


John,
Did any of the other LEDs come on?  All I had was power for a few hours.....not to mention the lack of 
communications....

Bob


----- Original Message ----- 
From: "John Allen" <john at pcsupportsolutions.com>
To: "'Discussion of precise time and frequency measurement'" <time-nuts at febo.com>
Sent: Sunday, May 23, 2010 12:36 AM
Subject: Re: [time-nuts] Z3805 utility, Was: AW: (no subject)


> Bob - I have a Symmetricom/HP Z3805.  When I first got it I powered it up in the
> North end if my house, where car GPS's can't lock, left it on for a day or more,
> and it locked.  No computer involved.  The antenna is a MA/COM mag mount from
> 1997.
> I bought the unit from fluke.l on ebay from China.
>
> John Allen K1AE
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf
> Of Robert Benward
> Sent: Saturday, May 22, 2010 11:31 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Z3805 utility, Was: AW: (no subject)
>
> Thank you all for these inputs!
>
> Most importantly, the big question is:  Regardless of RS-232 or 422, will the
> unit do ANYTHING without communications?
> Do I need a computer to get anything beyond the "power" led?
>
> I bought this at the Dayton convention ham flea market, and the guy told me it
> was already modified for RS-232.  The
> board inside says RS-422 near the connector.  Without the other LEDs blinking,
> I'm worried I bought a dead unit.  I had
> a GPS antenna on it, but it never locked on.  Do I need a computer to enable
> this thing?
>
> Thanks,
> Bob
>
> ----- Original Message ----- 
> From: "Bob Camp" <lists at rtty.us>
> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Sent: Saturday, May 22, 2010 10:54 PM
> Subject: Re: [time-nuts] Z3805 utility, Was: AW: (no subject)
>
>
>> Hi
>>
>> In this case the RS relates to Radio Shack ......
>>
>> Not a lot of standardization in the RS-232 world. Take a look at the slew rate
> limiting requirements in the original
>> document ...
>>
>> Bob
>>
>> On May 22, 2010, at 9:47 PM, Robert Darlington wrote:
>>
>>> Was there ever a standard?  I always thought the "RS" stood for
>>> Recommended Standard, as in "you *should* do the following" as
>>> compared to "you shall do the following"  I've seen inverted TTL talk
>>> to the RS232 port on laptops and I even sometimes use the max233's
>>> (+/- 10 volts instead of 12), but always use the full max232 with
>>> external charge pumps when it's a gadget that needs to work everytime
>>> with systems from multiple countries.
>>>
>>> -Bob
>>>
>>> On Sat, May 22, 2010 at 7:21 PM, Didier Juges <didier at cox.net> wrote:
>>>> Bruce,
>>>>
>>>> Thanks for the additional information.
>>>>
>>>> +/- 14V is quite unusually low in my experience. I typically use Maxim parts
> such as the MAX220 series, which is
>>>> specified at +/-25V for no damage on the inputs (some parts in that series
> go to +/-30V).
>>>>
>>>> The bottom line is that as I pointed out earlier, there is no such thing as
> an RS-232 standard any more.
>>>>
>>>> Didier
>>>>
>>>> ------------------------ Sent from my BlackBerry Wireless thingy while I do
> other things...
>>>>
>>>> -----Original Message-----
>>>> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>>>> Date: Sun, 23 May 2010 10:39:21
>>>> To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
>>>> Subject: Re: [time-nuts] Z3805 utility, Was: AW:  (no subject)
>>>>
>>>> Didier Juges wrote:
>>>>> Bill, I think you got it backwards. +/- 12V is typical for RS-232, 0/+5V is
>>>>> for RS-422 and RS-485.
>>>>>
>>>>> No RS-232 receiver should be damaged with +/- 12V or even +/- 15V because
>>>>> that is their normal operating voltage.
>>>>>
>>>>> Also, RS-422 and RS-485 have something like 25V common mode tolerance (not
>>>>> sure what the actual spec is there,) so that the RS-422 and RS-485
> receivers
>>>>> should not be damaged by 15V either. The RS-422 drivers are pretty low
>>>>> impedance, while the RS-232 drivers are current limited, so I don't think
>>>>> that connecting an RS-232 driver into an RS-422 driver will damage either.
>>>>>
>>>> Picking one RS485 receiver (ADM1485) at random the receiver absolute
>>>> maximum (no damage) input range is -14V to +14V.
>>>> The RS485 receiver operating common mode range is -7V to +12V.
>>>> RS422 receivers have an input operating range of -7V to +7V.
>>>> The no damage RS422 receiver input ratings may be higher.
>>>>> However, most recent (<10 years?) RS-232 receivers will work with a 0/+3V
> or
>>>>> 0/+5V input, conveniently having a threshold a few 10's or 100's of mV
> above
>>>>> ground, even though the original RS-232 spec required receivers that work
>>>>> with as low as +/- 3V, and drivers that deliver +/- 9V minimum. Many
>>>>> commercial systems use +/- 5V drivers for RS-232 (B&B Electronics sells a
>>>>> lot of converters with these voltages). This is a deliciously sloppy spec
>>>>> that nobody has met in the last 25 years probably, yet works most of the
>>>>> time.
>>>>>
>>>>> The one thing to avoid is to short an RS-422 (or RS-485) driver to ground,
>>>>> as that can actually cause damage, maybe not every time, but definitely not
>>>>> recommended. These have relatively high current output capability to drive
>>>>> long lines.
>>>>>
>>>>> Didier KO4BB
>>>>>
>>>>>
>>>>>
>>>> Bruce
>>>>> -----Original Message-----
>>>>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>>>>> Behalf Of Bill Hawkins
>>>>> Sent: Saturday, May 22, 2010 3:09 PM
>>>>> To: 'Discussion of precise time and frequency measurement'
>>>>> Subject: Re: [time-nuts] Z3805 utility, Was: AW: (no subject)
>>>>>
>>>>> When all else fails, get out the voltmeter.
>>>>>
>>>>> Do you have power to the antenna? Is it the right voltage? All the way to
>>>>> the antenna?
>>>>>
>>>>> What volts are on pins 2 or 3 relative to pin 7 in the comm connector?
>>>>>
>>>>> If you see 12 volts, that's RS-422. You may have burned out your computer's
>>>>> serial port.
>>>>>
>>>>> If you see less than 5 volts, that's RS-232 and all should be well, unless
>>>>> you see zero volts.
>>>>>
>>>>> I may have the RS-xxx volts somewhat off because my memory isn't what it
>>>>> used to be.
>>>>>
>>>>> The guy you bought it from should be able to help with comm basics.
>>>>>
>>>>> Bill Hawkins
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>>>>> Behalf Of Robert Benward
>>>>> Sent: Saturday, May 22, 2010 2:08 PM
>>>>> To: Discussion of precise time and frequency measurement
>>>>> Subject: Re: [time-nuts] Z3805 utility, Was: AW: (no subject)
>>>>>
>>>>> Hi All,
>>>>> I hooked everything up and I still get nothing.  I can't seem to establish
>>>>> communications  with the Z3805.  I tried a
>>>>> null modem as well, in case the cable (supplied) was wired with the wrong
>>>>> connector gender.  I see a green blinking
>>>>> light inside, it he left rear corner of the box.  Everything is warm, but
>>>>> nothing else.  Any ideas?
>>>>>
>>>>> Bob
>>>>>
>>>>>
>>>>>
>>>>>
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>>>>
>>>>
>>>>
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