[time-nuts] Looking to find an antenna for a TrueTime XL-DC

[Gregory Beat]

Here is the Manual for the True Time XL-DC (circa 1997-1999)
http://glacier.lbl.gov/gtp/DOM/Support/xl-dc-manual.pdf

gb

Sent from iPad Air
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Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[ziggy9+time-nuts]

It's an SV6 (SVeeSix), marked TNL 22880-B on the board. On the other
hand, I guess you could also say it wasn't an ACTUAL SV6 because of the
customization done for Datum/TrueTime. Pictures are in the EEVBlog thread
at



The replacement I hacked came from a Placer 400 mobile unit. Not all
Placer 400 have SV6 in them though, one I got had an SV8 in it.

  08/09/2016 04:34 AM, Hal Murray wrote:
> ziggy9+time-n...@pumpkinbrook.com said:
>> It IS possible to hack a ’standard’ SV6 receiver such that it will work 
>> in
>> the XL-DC...
> Did your XL-DC have an actual SV6 in it?  I didn't see one in the picture 
> Rick sent out a few days ago.  There was a Trible sticker on a chip so I 
> suppose the logic from  a SV6 could have been laid out as part of another 
> board.
>
>
>
>
>
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Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[Tim Shoppa]

My first ever GPS receiver was a surplus SV6. Wow, that's a primitive
receiver. The PPS would shift by 6 milliseconds (not microseconds, but
milliseconds) every time I didn't have enough satellites in view.

Tim N3QE

On Tue, Aug 9, 2016 at 4:34 AM, Hal Murray  wrote:

>
> ziggy9+time-n...@pumpkinbrook.com said:
> > It IS possible to hack a ’standard’ SV6 receiver such that it will work
> in
> > the XL-DC...
>
> Did your XL-DC have an actual SV6 in it?  I didn't see one in the picture
> Rick sent out a few days ago.  There was a Trible sticker on a chip so I
> suppose the logic from  a SV6 could have been laid out as part of another
> board.
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
>
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Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[Hal Murray]

ziggy9+time-n...@pumpkinbrook.com said:
> It IS possible to hack a ’standard’ SV6 receiver such that it will work in
> the XL-DC...

Did your XL-DC have an actual SV6 in it?  I didn't see one in the picture 
Rick sent out a few days ago.  There was a Trible sticker on a chip so I 
suppose the logic from  a SV6 could have been laid out as part of another 
board.



-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[ziggy9+time-nuts]

For antennas, I believe you’re looking for one of:
142-401
142-602
142-603
142-610
According to legend, these are 12V antennas, using a 16.368MHz LO and 4.092MHz 
IF to the receiver. Good luck in finding one :) But if you are diligent and 
patient, they do sometimes appear.
It IS possible to hack a ’standard’ SV6 receiver such that it will work in the 
XL-DC, but it’s not for the faint of heart. Besides significant modifications 
to the GPS receiver board you need to modify the main board too. In a nutshell, 
on the main board you need to remove a resistor and add a cap, and on the GPS 
board, you need to depopulate the oscillator, convert the line drivers from 
RS232, depopulate the unused serial port, depopulate the power supply section, 
and copy the EEPROM settings from an original TrueTime SV6. Contact me off list 
if you’re interested in more of the details. I didn’t do a complete 
documentation of the process but I have the unit I converted.
Paul
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Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[Rick Jones]

On 08/04/2016 04:10 PM, Rick Jones wrote:

I have been bequeathed a TrueTime XL-DC, Model 151-601-1, serial number
1671 per a sticker on the side.  On the back, on the right as one faces
the back, is a small sticker that says "Down Conv. Req'd"

Unsurprisingly, it has arrived without an antenna.  If the original
antenna still exists, it is on a building roof in Ft. Collins Colorado
and is likely effectively lost.  (I'm in Sunnyvale, CA)

HalM was kind enough to come over the other day with some antennae which
we tried without success.  Since then I've done a bit of web searching
and come across:

http://www.prostudioconnection.com/Symmetricom-TrueTime-GPS-Antenna-140-615-Downconve-p/282092173717.htm


It seems to be a part that was (also) included in a larger down/up
conversion product, the 140-6150.  I was wondering if the naive
assumption that "TrueTime down conversion is TrueTime down conversion"
and the sticker on the back of the DC-XL might mean the 140-615 antenna
would work with the DC-XL?



In parallel I contacted the support folks at Microsemi via their 
website.  They were kind enough to reply to let me know that the 142-615 
will not work with the downconverted XL-DC model above.  They suggested 
that perhaps a 142-603 or 142-610 would work so I'll cast about the web 
some more.


happy benchmarking,

rick jones

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Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[Bob Camp]

Hi

Add in variables like supply voltage, tuning approach, signal levels, and gain 
….

There are a lot of things you need to match up to get a downconverter going 
with an old style GPS. Once you do, you then likely have a unit that has GPS
epoch roll over issues. It may have other firmware quirks as well. 

None of that says “don’t do it”. It simply is a caution that this is a labor of 
love rather
than one getting a useful piece of gear up and going. You may ultimately have 
something
useful, the odds are it will have bugs …

Bob


> On Aug 6, 2016, at 9:44 AM, paul swed  wrote:
> 
> Completely agree with the comment on working with other receivers.
> The down converters had to match the IF and there were at that time at
> least 2 IF frequencies 75 and 34 MHz as I recall.
> But that said no idea what they may cost and is it worth the gamble.
> Or reach out to meinberg and ask.
> Regards
> Paul
> WB8TSL
> 
> On Sat, Aug 6, 2016 at 4:19 AM, Martin Burnicki <
> martin.burni...@burnicki.net> wrote:
> 
>> Alexander Pummer wrote:
>>> Meinberg https://www.meinbergglobal.com/ makes complete down and up
>>> converter for GPS remote antennas
>> 
>> That's true, but they have been designed for the frontend assembled in
>> Meinberg GPS receivers. I doubt they work with Truetime devices.
>> 
>> Martin (working @Meinberg)
>> 
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Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[paul swed]

Completely agree with the comment on working with other receivers.
The down converters had to match the IF and there were at that time at
least 2 IF frequencies 75 and 34 MHz as I recall.
But that said no idea what they may cost and is it worth the gamble.
Or reach out to meinberg and ask.
Regards
Paul
WB8TSL

On Sat, Aug 6, 2016 at 4:19 AM, Martin Burnicki <
martin.burni...@burnicki.net> wrote:

> Alexander Pummer wrote:
> > Meinberg https://www.meinbergglobal.com/ makes complete down and up
> > converter for GPS remote antennas
>
> That's true, but they have been designed for the frontend assembled in
> Meinberg GPS receivers. I doubt they work with Truetime devices.
>
> Martin (working @Meinberg)
>
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Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[Martin Burnicki]

Alexander Pummer wrote:
> Meinberg https://www.meinbergglobal.com/ makes complete down and up
> converter for GPS remote antennas

That's true, but they have been designed for the frontend assembled in
Meinberg GPS receivers. I doubt they work with Truetime devices.

Martin (working @Meinberg)

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Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[Alexander Pummer]

Meinberg https://www.meinbergglobal.com/ makes complete down and up 
converter for GPS remote antennas


73
KJ6UHN
Alex

On 8/5/2016 3:11 PM, Rick Jones wrote:

On 08/04/2016 06:02 PM, Hal Murray wrote:


rick.jon...@hpe.com said:
HalM was kind enough to come over the other day with some antennae 
which  we

tried without success.


I was going to suggest taking the cover off and looking inside but it 
fell

off my to-do list.

GPS receivers are reasonably specialized.  I doubt it anybody makes one
targeted at the down-converter market.

Is there an up-converter in there feeding a normal receiver?  If so, 
it might

be possible/easy to bypass.

If it looks like a direct connection to a normal receiver, I'd guess 
it has
special firmware.  It might be possible to replace it with one with 
normal

firmware.


My peanut gallery level of knowledge means I wouldn't recognize a 
normal receiver if it reared up and, well, you know :)


I do though have some pictures of the relevant section of the machine 
with the cover off - two of the same shot at:


ftp://ftp.netperf.org/dc-xl

The antenna connection is the silver "square" on the left.  There are, 
as you can see, a number of jumpers everywhere.  The daughter card is 
connected at its "top left" in the picture where those "5s" of posts 
are.  There are some shiny gold (plated?) posts there underneath them, 
and a couple other vertical connections more towards the center.


That entire assembly can slide out of the chassis after removing four 
screws at the back.  I didn't try to remove the daughter card.


rick jones

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Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[Rick Jones]

On 08/04/2016 06:02 PM, Hal Murray wrote:


rick.jon...@hpe.com said:

HalM was kind enough to come over the other day with some antennae which  we
tried without success.


I was going to suggest taking the cover off and looking inside but it fell
off my to-do list.

GPS receivers are reasonably specialized.  I doubt it anybody makes one
targeted at the down-converter market.

Is there an up-converter in there feeding a normal receiver?  If so, it might
be possible/easy to bypass.

If it looks like a direct connection to a normal receiver, I'd guess it has
special firmware.  It might be possible to replace it with one with normal
firmware.


My peanut gallery level of knowledge means I wouldn't recognize a normal 
receiver if it reared up and, well, you know :)


I do though have some pictures of the relevant section of the machine 
with the cover off - two of the same shot at:


ftp://ftp.netperf.org/dc-xl

The antenna connection is the silver "square" on the left.  There are, 
as you can see, a number of jumpers everywhere.  The daughter card is 
connected at its "top left" in the picture where those "5s" of posts 
are.  There are some shiny gold (plated?) posts there underneath them, 
and a couple other vertical connections more towards the center.


That entire assembly can slide out of the chassis after removing four 
screws at the back.  I didn't try to remove the daughter card.


rick jones

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Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[Hal Murray]

rick.jon...@hpe.com said:
> HalM was kind enough to come over the other day with some antennae which  we
> tried without success. 

I was going to suggest taking the cover off and looking inside but it fell 
off my to-do list.

GPS receivers are reasonably specialized.  I doubt it anybody makes one 
targeted at the down-converter market.

Is there an up-converter in there feeding a normal receiver?  If so, it might 
be possible/easy to bypass.

If it looks like a direct connection to a normal receiver, I'd guess it has 
special firmware.  It might be possible to replace it with one with normal 
firmware.


-- 
These are my opinions.  I hate spam.



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[time-nuts] Looking to find an antenna for a TrueTime XL-DC

[Rick Jones]

I have been bequeathed a TrueTime XL-DC, Model 151-601-1, serial number 
1671 per a sticker on the side.  On the back, on the right as one faces 
the back, is a small sticker that says "Down Conv. Req'd"


Unsurprisingly, it has arrived without an antenna.  If the original 
antenna still exists, it is on a building roof in Ft. Collins Colorado 
and is likely effectively lost.  (I'm in Sunnyvale, CA)


HalM was kind enough to come over the other day with some antennae which 
we tried without success.  Since then I've done a bit of web searching 
and come across:


http://www.prostudioconnection.com/Symmetricom-TrueTime-GPS-Antenna-140-615-Downconve-p/282092173717.htm

It seems to be a part that was (also) included in a larger down/up 
conversion product, the 140-6150.  I was wondering if the naive 
assumption that "TrueTime down conversion is TrueTime down conversion" 
and the sticker on the back of the DC-XL might mean the 140-615 antenna 
would work with the DC-XL?


thanks muchly,

rick jones
intrigued member of the peanut gallery
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