[time-nuts] update on LTE-Lite

GandalfG8 at aol.com GandalfG8 at aol.com
Sat Nov 22 15:21:40 EST 2014

Hi Said,
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)  

Hi Said,
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:

Hello everyone, 
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. 
More later, 
Said  Jackson 
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)  
_www.jackson-labs.com_ (http://www.jackson-labs.com/)  


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