[time-nuts] update on LTE-Lite
GandalfG8 at aol.com
GandalfG8 at aol.com
Sat Nov 22 15:21:40 EST 2014
Many thanks for your reply.
I'd realised that R2 and R3 were in the paths of alternative power feeds
but had managed to convince myself that both resistors were shown to be
fitted in your auction photos, although I can now see quite clearly that whilst
R2 is fitted, R3 isn't, whoops:-)
I was hoping that removing the TXCO might be reasonably straightforward, it
was after all your suggestion:-), but am now concerned that the RTV might
have flowed under any components perhaps not fully seated and didn't want
to take the risk of damaging anything. I'd also hoped it might prove
possible to remove the onboard TCXO power by breaking one of the tracks on the
LTE-Lite module itself but it sounds like that might have been a bit too
Whilst I'm pretty sure I would have stuck with the 20MHz version anyway,
the initial enthusiastic rush did mean nearly 40 of us had already bought
them before your comments regarding the harmonic mixing and the suggestion to
use the 19.2MHz version reached the list, so to some extent at least that
might help explain the numbers:-)
Anyway, thanks very much again for making these available, I certainly
don't see this as a significant issue so it's time to dive in and worry about
the finer details later.
Just out of interest, on the 10MHz version without the onboard TCXO, did
the DIL oscillator end up socketed or soldered?
In a message dated 22/11/2014 18:01:18 GMT Standard Time,
saidjack at jackson-labs.com writes:
CC'ing time nuts..
R2 and R3 are stuffing options, see the schematics in the user manual.
Typically you don't have to solder anything. The default is set for the
low-noise 3.0V to be fed to the DIP-14 tcxo for best performance.
On removing the SMT Tcxo, this is not easy, but possible with a heat gun.
Its easy to melt the adjacent switches though when doing that. The RTV over
it should just peel off, but we have not tried that yet. There is no way to
just remove power to the internal Tcxo unfortunately.
This is why I had suggested the 19.2MHz version for people who want to use
the external oscillator option, because that won't beat with your
oscillator close-in. I was a bit surprised that so few of those 19.2MHz units sold
compared to the significant numbers for 10/20MHz units. In either case I
think the resulting beat spurs are typically lower than many other GPSDOs and
oscillators have in their spurs, the CSAC with its spurs comes to mind..
Hope that helps,
Sent from my iPad
On Nov 22, 2014, at 6:08, _GandalfG8 at aol.com_ (mailto:GandalfG8 at aol.com)
Sorry to bother you again, I'm not sure is this is an oversight or
deliberate but I've just noticed that R2 has not been fitted to my evaluation
I'm a bit concerned as this will affect power to the external oscillator
and R2 would be difficult to fit now that SW2 is installed.
I may have missed this if it was mentioned on the Time-Nuts list but
there's a lot there to look through so thought it best to ask you direct.
In a message dated 30/10/2014 23:30:40 GMT Standard Time,
_saidjack at jackson-labs.com_ (mailto:saidjack at jackson-labs.com) writes:
We wanted to give you an interim update on the LTE-Lite Evaluation kit
builds. We are making good progress on the assembly. We are expecting to ship
within the announced time frame, and are guiding the factory on a daily
We are using the time to improve the firmware and have made some upgrades
with the help and efforts of a very well-known Time Nut (thanks much!) who
I am certain will identify himself in due time. This development activity
has revealed a sensitivity in the GPS receiver: the unit should not be
changed from mobile mode to Position Hold (Timing) mode ROM/Flash firmware or
vice versa while power is enabled, this could lead to Flash memory
corruption. We are thus shipping the unit with a solder jumper that will require
soldering-in two pins to get out of Timing mode and into mobile mode so as to
avoid the possibility of a user accidentally inserting a jumper with power
supplied to the unit, which could then corrupt the GPS Flash memory. We have
also been able to upgrade the GPS Flash firmware in close cooperation with
the vendor of the GPS receiver to make it more optimal for operation in a
GPSDO, and these efforts have given us a GPS Flash firmware release that
works well with our GPSDO algorithms and TCXOs. We will upgrade all of the
GPS receivers prior to shipment with this specialized firmware release.
We also have some good news on the 10MHz versions of the board: the 10MHz
DIP-14 TCXOs are scheduled to arrive at our factory in about 5 weeks, so
that will pull-in the delivery schedule significantly. We will continue to
keep track of the schedule and update you with any changes.
Lastly there has been some fairly intense discussion recently about
counter-fit FTDI serial chips getting permanently disabled by the latest FTDI
software drivers and thus rendering affected equipment unusable. Many links
have been published on Time-Nuts so please consult the archives for more
information on this issue.
We use FTDI chips on many of our products, such as the CSAC GPSDO,
Mini-JLT, LC_XO Plus kit, and also this LTE-Lite Eval kit. We are pleased to
announce that we have verified with our suppliers that all of our shipments in
the past and in the future have and will continue to use genuine FTDI chips.
Close inventory control and counter-fit policies are one advantage of
manufacturing in the USA versus in Asia.
Jackson Labs Technologies, Inc.
1635 Village Center Circle, Suite 150
Las Vegas, NV 89134
Tel. (408) 596-0600
Fax. (702) 233-1073
_saidjack at jackson-labs.com_ (mailto:saidjack at jackson-labs.com)
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