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

Sun May 23 03:30:57 UTC 2010

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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