[time-nuts] Difference between Oncore models

Joseph Gray jgray at zianet.com
Wed Mar 16 21:56:57 EDT 2016


Thanks to all for the comments. I recently traded for another Z3801A
that I was told didn't work. I don't know what is wrong with it, as I
haven't had time to put it on the bench yet. I understand that the
OCXO is putting out a decent 10 MHz, so perhaps it also has a bad
Oncore.

Joe Gray
W5JG


On Wed, Mar 16, 2016 at 3:56 PM, Artek Manuals <Manuals at artekmanuals.com> wrote:
> Joe
>
> The newer Motorola VP-Oncore  receivers are known to be an improved design
> over the original Oncores that came with the Z3801A's .
>
> I have recently done some  side by side comparison's with two z3801A's on
> the same antenna the newer Vp-Oncore's ran SS numbers 15-30 points higher on
> the same bird than the older receiver. In all fairness the older receiver is
> on its last legs (see last paragraph below)
>
> I also found out that there are two versions of the newer VP-Oncore. These
> can be distinguished by the antenna connector, One version has a right-angle
> chassis mounted connector like the original 6CH Oncore, the 2nd version has
> a straight on antenna connector. This 2nd version while they will work in a
> Z3801A, have an interference fit problem with a an IC  on the board below
> when the antenna cable is plugged in and you can't tighten down all the
> receiver board mounting screws. I am told that the straight on version fits
> the Z3816A with no problem. I have not verified this since I don't have a
> Z3816. I have no info  on the other Z38xx models and the fit of the later
> VP-Oncore
>
> The older 6ch Oncore receivers receivers are beginning to die apparently.  I
> have had one fail here a few months ago and recently acquired a 2nd Z3801A
> that is displaying similar symptoms to the first failure in that the
> receiver just stops working after a few hours...over time the symptom  are
> the receiver drops out for no apparent reason then revives if the unit is
> powered off for a while. Over time the time to receiver drop out gets
> shorter and shorter after each successive power cycle, I have one receiver
> that will now fail within 20 minutes predictably.
>
> Dave
> NR1DX
>
>
>
>
> On 3/16/2016 7:03 AM, Joseph Gray wrote:
>>
>> I understand that the Oncore GPS in the Lucent units is a newer module
>> that tracks eight satellites, vs the older Oncore in the Z3801A that
>> only tracks six satellites.
>>
>> I decided to do a re-survey with my Z3801A that has been in holdover
>> for some time, just as a test. Watching the status screens from both
>> GPSDOs, both are seeing the same number of satellites, however, the
>> Z3801A is consistently locking to 3-4 fewer than the Lucent.
>>
>> This begs the question, is the older Oncore module that deaf, or is
>> mine defective. BTW, same antenna on a 4-port splitter, same elevation
>> mask.
>>
>> Joe Gray
>> W5JG
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>
>
> --
> Dave
> Manuals at ArtekManuals.com
> www.ArtekManuals.com
>
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