[time-nuts] Difference between Oncore models

Artek Manuals Manuals at ArtekManuals.com
Wed Mar 16 17:56:00 EDT 2016


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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