[time-nuts] Introduction and info about a Lucent RFTG

[paul swed]

Email is getting really annoying. Gmail makes you do a dance to get it
active again. So here is my response a second time.
The system has a RB and a fine oven osc that is disciplined to the RB in
case the RB fails. The xtals pretty nice and even though an oven draws
quite low current when warm.
Both the RB and Xtal connect to a 2 way combiner to 9 way splitter for
passive distribution.
Regards
Paul
WB8TSL


On Sat, Jul 5, 2014 at 8:06 AM, <GandalfG8 at aol.com> wrote:

> Hi Denver
>
> When you refer to one "side" or the other, do you have the complete RFTG
> unit with the two modules?
> I only have the internals of the Rubidium module so would hardly claim to
> be an expert on these, or on much else for that matter:-), but as I
> understand  it from the documentation this is a "reduntant" system, in
> that either
> the GPSDO  or the Rubidium module is active at any one time with the other
> in
>  standby.
> In other words, there's no suggestion that the Rubidium module is locked to
>  GPS, it is indeed free running, whilst the GPS module is used to
> discipline  its own crystal oscillator.
> However, although the "free running" Rubidium module will need occasional
> adjustment, as opposed to the GPSDO wich shoudn't, a free running Rubidium
> reference is still not something to be sneezed at.
>
> Section 2.1 "RFTG Functionality", in the documentation refers to this in
> more detail.
>
> There was a fair bit of discussion here at one time regarding these so I'm
> surprised you haven't found more in the archives. For example, another list
>  member, Skip Withrow, produced an article in January 2013 detailing how to
>  modify the RFTGm GPSDO to obtain a 10MHz output, which he suggests should
> also  apply to the earlier versions and I've also seen information on the
> Rubidium  modules.
>
> Because my Rubidium module arrived with just the two  attached PCBs and no
> outer metalwork whatsoever it was easier for me anyway  to just put the
> 15MHz generator board to one side and use the interface board  only with
> its
> special D connector still attached to make the thing  functional.
> If I'd had the complete unit, including metalwork, I would probably have
> approached it differently.
>
> On my unit at least the actual Rubidium module was an Efratom FRS  and
> there's documentation available online for these should you wish to run  it
> stand alone
> However, it would seem to me that without too much work, and utilising  the
> existing metalwork, these two units between them could provide the basis
> for  a 10MHz Rubidium Standard plus a separate 10MHz GPSDO,  but turning
> them
> into a GPS disciplined Rubidium unit perhaps not quite so
> straightforward:-)
>
> Regards
>
> Nigel
> GM8PZR
>
>
> In a message dated 05/07/2014 07:38:44 GMT Daylight Time,
> dencohe at gmail.com
>  writes:
>
> Thank  Rex and Paul for the replies
>
> From what I understand my RFTG has a GPSDO  on oneside that has a crystal
> oven inside it, and a rubidium source on the  other side. The rubidium
> source takes a signal from the GPSDO side and uses  that for longer term
> stability. But If I am understanding you, Rex, that  the rubidium is really
> not a gps locked oscillator and just a free running  device. I will start
> tearing down the unit to figure out if I can make  something more usable
> out
> of it. I will make sure to document it and post  it somewhere on the web. I
> read somewhere on this group that there is a way  to bypass the 15MHz
> generating circuit and use the existing hardware  amplifier and
> distribution
> at 10MHz. I will also be looking into that as  well. Rex, you are correct
> as
> there is no power supply inside and I have it  hooked up to a open frame
> type switching supply externally.
>
> Paul - I  will be setting up my GPS antenna shortly and trying to get it to
> lock to  GPS for a more precise reference.
>
> Thanks all
> -Denver
>
>
> On  Fri, Jul 4, 2014 at 9:38 PM, Rex <rexa at sonic.net> wrote:
>
> >  Several years ago there were a number of these showing up pretty cheap
> on
> > eBay, so I bought one. As I recall there were a couple of similar
> versions
> > with some differences so take this recollection with a grain  of salt.
> >
> > I did some tracing of the internals on the one I had  and found the
> > rubidium unit had no connection on the tuning pin  (C-field) to the board
> > circuits. So it was free running, only for  backup in the system, and not
> > GPS lockable. I don't remember there  being any useful power supply in
> the
> > box, so my advice would be to  remove the LPRO rubidium and use it
> directly.
> > (It does need heat  sinking, so maybe some parts of the box mechanicals
> are
> > useful.) In my  opinion, working out how to use the supporting circuit
> board
> > is not  worth the effort, unless you really have a need for the 15 MHz
> they
> >  create.
> >
> > You should be able to find documentation for the  internal module LPRO
> > rubidiums on the web. I haven't looked today but  KO4BB site probably has
> it.
> >
> >
> >
> > On 7/4/2014 1:47  PM, Denver wrote:
> >
> >> Hi all,
> >>
> >> My name  is Denver I am currently a freshman in college and the time bug
> >>  has
> >> struck me. I recently acquired a Lucent RFTG on ebay to have a  time
> >> standard for my lab(and yes already realize its 15MHz output  but may be
> >> able to change that and or just use the 10MHz test  point from the
> rubidium
> >> source). I made a power connector for it.  Now that I have power applied
> >> and
> >> sort of verified its  operation I am looking for more info about the
> >> connectors on the  front panel. I have the KO4BB user documentation on
> it
> >> but it  doesn't mention much about connectors and pinouts. I also have
> >>  already searched the group for other mentions of the RFTG but all I  am
> >> able
> >> to come up with is some of the newer models  the -m and such. Maybe one
> of
> >> you could help point me in the right  direction or give me some other
> ideas
> >> on how to get more use out  of this unit.
> >>
> >> Thanks in advance
> >>  -Denver
> >>  _______________________________________________
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> >>
> >>
> >>
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