Re: [time-nuts] Tait reference

[Adrian Godwin]

Good news - my purchase arrived quickly, contains an FE5660A 10MHz
oscillator and shows both the internal standard lock light and the internal
reference lock light within a few minutes. It runs from 13.8 volts and
takes about 1.2A.

The f1 and f2 lock lights don't come on, but that's not a big issue. I may
just rewire those outputs as a distribution amplifier in any case.


On Tue, Jan 12, 2016 at 5:46 PM, Adrian Godwin  wrote:

> If so, let's hope the sudden surge of purchases will encourage the dealer
> to find some more :)
>
>
> On Tue, Jan 12, 2016 at 1:39 PM, Clint Jay  wrote:
>
>> That's a very happy coincidence and one I'd hoped to hear.
>>
>> The pictures in the auction seem to show a lack of tarnish on the Ref Out
>> and Ref In BNCs which suggests they have had plugs on them, looping the
>> internal reference, other little bits of information also pointed to that,
>> the remnants of a sticker on the front of one unit seems to say
>> 'RUBID01...', past auctions of T801 units have been labelled with things
>> like 'RUBID048', the hex switches seem to be set correctly for use with an
>> internal reference as well so I was quietly confident they had the Rb
>> option fitted.
>>
>> Now I just have to cross my fingers that mine arrive with the Rb in good
>> conditon. The seller also states 'working order' so there's possible scope
>> for a refund if it doesn't.
>>
>> On 12 January 2016 at 12:24, GandalfG8--- via time-nuts <
>> time-nuts@febo.com>
>> wrote:
>>
>> > Are these the references with a rubidium oscillator ?  They seem  to
>> have
>> > similar models with OCXOs etc.
>> > http://www.ebay.co.uk/itm/111862884745
>> >
>> > ---
>> > Well now, how's this for a happy coincidence.
>> >
>> > I've just received an email from a friend who bought a Tait T801 from
>> that
>> > very same auction, asking about the rubidium module that he  found
>> inside
>> > it:-)
>> >
>> > Regards
>> >
>> > Nigel
>> > Gm8PZR
>> > ___
>> > time-nuts mailing list -- time-nuts@febo.com
>> > To unsubscribe, go to
>> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> > and follow the instructions there.
>> >
>>
>>
>>
>> --
>> Clint.
>>
>> *No trees were harmed in the sending of this mail. However, a large number
>> of electrons were greatly inconvenienced.*
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>>
>
>
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Re: [time-nuts] Tait reference

[GandalfG8--- via time-nuts]

Are these the references with a rubidium oscillator ?  They seem  to  have
similar models with OCXOs etc.
http://www.ebay.co.uk/itm/111862884745
 
---
Well now, how's this for a happy coincidence.
 
I've just received an email from a friend who bought a Tait T801 from  that 
very same auction, asking about the rubidium module that he  found inside 
it:-)
 
Regards
 
Nigel
Gm8PZR
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Re: [time-nuts] Tait reference

[Clint Jay]

That's a very happy coincidence and one I'd hoped to hear.

The pictures in the auction seem to show a lack of tarnish on the Ref Out
and Ref In BNCs which suggests they have had plugs on them, looping the
internal reference, other little bits of information also pointed to that,
the remnants of a sticker on the front of one unit seems to say
'RUBID01...', past auctions of T801 units have been labelled with things
like 'RUBID048', the hex switches seem to be set correctly for use with an
internal reference as well so I was quietly confident they had the Rb
option fitted.

Now I just have to cross my fingers that mine arrive with the Rb in good
conditon. The seller also states 'working order' so there's possible scope
for a refund if it doesn't.

On 12 January 2016 at 12:24, GandalfG8--- via time-nuts 
wrote:

> Are these the references with a rubidium oscillator ?  They seem  to  have
> similar models with OCXOs etc.
> http://www.ebay.co.uk/itm/111862884745
>
> ---
> Well now, how's this for a happy coincidence.
>
> I've just received an email from a friend who bought a Tait T801 from  that
> very same auction, asking about the rubidium module that he  found inside
> it:-)
>
> Regards
>
> Nigel
> Gm8PZR
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 
Clint.

*No trees were harmed in the sending of this mail. However, a large number
of electrons were greatly inconvenienced.*
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Re: [time-nuts] Tait reference

[Adrian Godwin]

If so, let's hope the sudden surge of purchases will encourage the dealer
to find some more :)


On Tue, Jan 12, 2016 at 1:39 PM, Clint Jay  wrote:

> That's a very happy coincidence and one I'd hoped to hear.
>
> The pictures in the auction seem to show a lack of tarnish on the Ref Out
> and Ref In BNCs which suggests they have had plugs on them, looping the
> internal reference, other little bits of information also pointed to that,
> the remnants of a sticker on the front of one unit seems to say
> 'RUBID01...', past auctions of T801 units have been labelled with things
> like 'RUBID048', the hex switches seem to be set correctly for use with an
> internal reference as well so I was quietly confident they had the Rb
> option fitted.
>
> Now I just have to cross my fingers that mine arrive with the Rb in good
> conditon. The seller also states 'working order' so there's possible scope
> for a refund if it doesn't.
>
> On 12 January 2016 at 12:24, GandalfG8--- via time-nuts <
> time-nuts@febo.com>
> wrote:
>
> > Are these the references with a rubidium oscillator ?  They seem  to
> have
> > similar models with OCXOs etc.
> > http://www.ebay.co.uk/itm/111862884745
> >
> > ---
> > Well now, how's this for a happy coincidence.
> >
> > I've just received an email from a friend who bought a Tait T801 from
> that
> > very same auction, asking about the rubidium module that he  found inside
> > it:-)
> >
> > Regards
> >
> > Nigel
> > Gm8PZR
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
>
>
>
> --
> Clint.
>
> *No trees were harmed in the sending of this mail. However, a large number
> of electrons were greatly inconvenienced.*
> ___
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Re: [time-nuts] Tait reference

[GandalfG8--- via time-nuts]

 
Thank you Nigel, I've also taken a gamble on one of these units and  am
keeping my  fingers crossed that it has a Rb standard in it.
The  service manual is most interesting, it looks like I could use one of
the two  'loops' to lock a different OCXO,  with a little tinkering it could
be a  very useful unit as there's plenty of space inside for additions  and
modifications.
Are these the references with a rubidium oscillator ?  They seem to  have
similar models with OCXOs etc.
http://www.ebay.co.uk/itm/111862884745
 
 
Hi Clint,
 
As far as I know, from the outside they all look the same and that's  the 
problem, there's no way I can tell you from the available photos whether or  
not those references have the rubidium oscillator.
 
I'd like to think they do, and will keep my fingers crossed for you, but  
unless you can get more info from the seller it'll just be a case of wait and 
 see.
 
Chances are that if the original batch was supplied with the rubidium  
modules then these will be too, might even be part of that same batch as I said 
 
earlier, but there's still the possibility they might not be the  same or 
might have been got at somewhere along the line.
 
I've just found an online photo that will show you what they "should"  look 
like inside
 
http://embarrados.com/market/item/111793998037/Tait-T801-Rubidium-Frequency-
Standard
 
Regards
 
Nigel
GM8PZR
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Re: [time-nuts] Tait reference

[Adrian Godwin]

Yes, i found that description and it put me off buying one. But there are
also references on the web (including time-nuts archive) to surplus T801s
with rubidium sources.

Anyway, I took a punt and bought one.
So I'll find out soon :).


On Mon, Jan 11, 2016 at 11:18 AM, Charles Steinmetz 
wrote:

> Adrian wrote:
>
> Are these the references with a rubidium oscillator ? They seem to have
>> similar models with OCXOs etc.
>>
>
> Tait is a manufacturer of mobile communications gear in New Zealand.  The
> T801 was part of a discontinued "quasi-synchronous communications system"
> -- a form of simulcasting on the same frequency by transmitters at
> different locations, to fill in dead spots.  Tait's application was utility
> and public service mobile radios (not radio broadcasting, where this scheme
> has also been used).  Here is Tait's basic description:
>
> The Tait Quasi-Synchronous Communication System works by broadcasting
>> simultaneously from several transmitters on the same frequency. The
>> transmitters then operate as a single transmitter giving superior coverage.
>>
>> A Tait T801 Frequency Referenct Module acurately maintains the frequency
>> of the transmitters at each site.
>>
>> Where required, the T801 allows small frequency offsets to prevent the
>> occurrence of static nulls in the overlap area.
>>
>> The T801 module may be driven from one of a number of frequency
>> references, such as:
>> -- Rubidium frequency standard
>> -- Broadcast frequency standard
>> -- Oven Controlled Crystal Oscillators (OCXOs)
>> -- GPS Caesium Clock
>>
>
> This suggests that the T801 does not have an internal frequency reference,
> but rather requires a precision external reference to function.  (It has a
> jack labeled "INTERNAL STD OUTPUT," but that may simply be a reference that
> is derived from the external standard, or a backup crystal oscillator to
> keep the transmitter more or less on frequency if the external reference
> signal is lost.)
>
> Best regards,
>
> Charles
>
>
>
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Re: [time-nuts] Tait reference

[Dave Brown]

Tait is a major mobile comms manufacturer-head office is here in 
Christchurch, NZ-a couple of miles down the road from me.
The T801 is/was often used in simulcast systems (which seem to be peculiar 
to the UK)  to lock up several base station equipments to a common 
reference-which is usually a 12.8 MHz high quality OCXO.  But I suggest you 
ask a few pertinent questions of the vendor to find out more about that 
particular box, as it may be slightly different, depending on where it came 
from.

DaveB, NZ



- Original Message - 
From: "Bob Camp" <kb...@n1k.org>
To: "Discussion of precise time and frequency measurement" 
<time-nuts@febo.com>

Sent: Monday, January 11, 2016 4:00 PM
Subject: Re: [time-nuts] Tait reference



Hi

Unless we are looking at different auctions, that one appears to want 13.8 
V at <= 5A

as the supply.

The BNC’s are also a fairly rare item in the Telco inventory (but not 
unheard of).


If I had to bet, I’d say it’s a piece of mobile video gear. I would not 
bet anything over
about a nickel on that being correct. It’s very much a mystery item other 
than possibly

having an offset frequency translation function.

Bob


On Jan 10, 2016, at 8:35 PM, paul swed <paulsw...@gmail.com> wrote:

What little I can tell is they are telco references so there may be
something good inside OCXO or RB. It looks like it runs on -48VDC from 
the
ebay pix. Its output could be any of the typical telco references that 
are

not 5 or 10 MHz. These are pure guesses. The Price seems reasonable.
Good luck
Paul
WB8TSL

On Sun, Jan 10, 2016 at 6:48 PM, Adrian Godwin <artgod...@gmail.com> 
wrote:



Are these the references with a rubidium oscillator ? They seem to have
similar models with OCXOs etc.

http://www.ebay.co.uk/itm/111862884745
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Re: [time-nuts] Tait reference

[Javier Herrero]

Hello,

Tait T800 is a series of mobile radio repeaters, so probably the T801 
could be a unit intended for iso-frequency networks, in which there are 
several repeaters are distributed in a wide area operating all at the 
same frequencies with a very tight tolerance. BNCs and 13.8V power 
supplies are very common in the mobile radio networks world.


Regards,

Javier

On 11/01/2016 4:00, Bob Camp wrote:

Hi

Unless we are looking at different auctions, that one appears to want 13.8 V at 
<= 5A
as the supply.

The BNC’s are also a fairly rare item in the Telco inventory (but not unheard 
of).

If I had to bet, I’d say it’s a piece of mobile video gear. I would not bet 
anything over
about a nickel on that being correct. It’s very much a mystery item other than 
possibly
having an offset frequency translation function.

Bob


On Jan 10, 2016, at 8:35 PM, paul swed  wrote:

What little I can tell is they are telco references so there may be
something good inside OCXO or RB. It looks like it runs on -48VDC from the
ebay pix. Its output could be any of the typical telco references that are
not 5 or 10 MHz. These are pure guesses. The Price seems reasonable.
Good luck
Paul
WB8TSL

On Sun, Jan 10, 2016 at 6:48 PM, Adrian Godwin  wrote:


Are these the references with a rubidium oscillator ? They seem to have
similar models with OCXOs etc.

http://www.ebay.co.uk/itm/111862884745
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Re: [time-nuts] Tait reference

[Steve Wiseman]

http://download.wrx.sk/pdfs/tait/Networks/Quasi.pdf says:

Quasi-Sync works by broadcasting simultaneously from several
transmitters on the same frequency. The transmitters then operate as a
single transmitter giving superior coverage. A Tait T801 Frequency
Reference Module accurately maintains the frequency of the
transmitters at each site. Where required, the T801 allows small
frequency offsets to prevent the occurrence of static nulls in the
overlap area. The T801 module may be driven from one of a number of
frequency references, such as; • Rubidium frequency standard •
Broadcast frequency standard • Oven Controlled Crystal Oscillators
(OCXOs) • GPS caesium clock

This doesn't sound like a reference source, or generally useful.

Steve
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Re: [time-nuts] Tait reference

[Alan Melia]

Its difficult to say unless you can contact an ex Tait dealer who maintained 
a Local authority or Utility scheme. A similar unit by Pye/Philips I have 
knowledge of, was the HS400. This contained a Toyocom 5MHz OCXO which was 
used to lock a crystal producing the required excitation for the (analogue) 
transmitter. There were two reasons for the offset, one was to avoid static 
nulls were two overlapping areas had out of phase signals, and the offset 
needed to be more than 20Hz (avoids flutter effects from the beats)and less 
than 50Hz to avoid confusing the CTCSS decoders (tone squelch).


However later Tait gear in the 800 series was synthersized, I believe, so 
this may be an stable reference source (OCXO or Rb) which could be daisy 
chained to all the channel transmitters in the site. Rubidium is not 
strictly necessary but was being installed in the 90s in some Police 
systems. In fact the Rapco GPSDOs available on eBay some couple of years ago 
came out, I believe, of London's Met Police system when they went digital.


Alan
G3NYK

- Original Message - 
From: "Adrian Godwin" <artgod...@gmail.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts@febo.com>

Sent: Monday, January 11, 2016 1:11 PM
Subject: Re: [time-nuts] Tait reference



Yes, i found that description and it put me off buying one. But there are
also references on the web (including time-nuts archive) to surplus T801s
with rubidium sources.

Anyway, I took a punt and bought one.
So I'll find out soon :).


On Mon, Jan 11, 2016 at 11:18 AM, Charles Steinmetz 
<csteinm...@yandex.com>

wrote:


Adrian wrote:

Are these the references with a rubidium oscillator ? They seem to have

similar models with OCXOs etc.



Tait is a manufacturer of mobile communications gear in New Zealand.  The
T801 was part of a discontinued "quasi-synchronous communications system"
-- a form of simulcasting on the same frequency by transmitters at
different locations, to fill in dead spots.  Tait's application was 
utility
and public service mobile radios (not radio broadcasting, where this 
scheme

has also been used).  Here is Tait's basic description:

The Tait Quasi-Synchronous Communication System works by broadcasting

simultaneously from several transmitters on the same frequency. The
transmitters then operate as a single transmitter giving superior 
coverage.


A Tait T801 Frequency Referenct Module acurately maintains the frequency
of the transmitters at each site.

Where required, the T801 allows small frequency offsets to prevent the
occurrence of static nulls in the overlap area.

The T801 module may be driven from one of a number of frequency
references, such as:
-- Rubidium frequency standard
-- Broadcast frequency standard
-- Oven Controlled Crystal Oscillators (OCXOs)
-- GPS Caesium Clock



This suggests that the T801 does not have an internal frequency 
reference,
but rather requires a precision external reference to function.  (It has 
a
jack labeled "INTERNAL STD OUTPUT," but that may simply be a reference 
that

is derived from the external standard, or a backup crystal oscillator to
keep the transmitter more or less on frequency if the external reference
signal is lost.)

Best regards,

Charles



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Re: [time-nuts] Tait reference

[GandalfG8--- via time-nuts]

Are these the references with a rubidium oscillator ? They seem to  have
similar models with OCXOs etc.
http://www.ebay.co.uk/itm/111862884745
 
Hi Adrian,
 
The T801 first seems to have hit the UK surplus market around  2005/2006, I 
was told a batch of a couple of hundred, and units from that  release were 
still trickling through until around 2011 at least.
These were released by West Yorkshire Police when updating their UHF  
mobile network and did contain rubidium standards.
 
The T801 contains dual nominal 12.8MHz  synthesisers with very fine 
switched preset adjustment for base  station synchronisation. These are locked 
to 
an  external reference and can accept selected integer frequencies  from 1 to 
10Mhz and also 12.8MHz.
If the internal 10MHz rubidium module is fitted and used as the  reference 
then a short BNC link is required to couple the internal  reference output 
to the external reference input.
 
These were originally sold on Ebay with particular reference to the  
rubidium module, for most purchasers the 12.8MHz synthesiser board would  
probably 
have been of little interest, so I'm surprised to see no reference to  the 
rubidium module with the several recent auctions. This may be due to  lack 
of familiarity on the part of the seller but I certainly wouldn't want to  
take anything for granted without asking.
I'm not sure either if the recent Ebay offerings are tail end leftovers  
from that first batch or represent a more recent release, but I have seen a  
number of failures with the rubidium modules in those bought between 2005  
and 2011.
One at least was physically faulty with others refusing to lock,  either at 
time of purchase or subsequently, I have some of the latter still  on the 
ever growing "to do" pile. 
 
According to the manual the rubidium module, where fitted,  was originally 
a Quartzlock TF4010A, but all units I've seen have been  fitted with FEI 
FE5660A modules. This required a degree of modification to  the chassis and to 
the heatsink and the quality of that work is often poor, so  quite likely a 
field "upgrade". 
 
The unit also contains a DC-DC convertor to derive the 24 Volt  supply for 
the rubidium module from the 13.8 Volt input.
The lock on the front panel is just an ON/OFF keyswitch, if the key is  
missing all those I've seen have been left in the ON position but it's easily  
bypassed anyway.
 
I've tried uploading my scan of the manual to Didier's site but gave  up 
after repeated page reset errors, it is now available  here..
http://www.mediafire.com/view/0x5sa7o0s9pgc4s/Tait_T801_Frequency_Reference.
pdf
 
Regards
 
Nigel
GM8PZR
 
 
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Re: [time-nuts] Tait reference

[David C. Partridge]

Is it possible to tell by looking at the back of the unit to determine if an Rb 
is fitted?

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Stephen 
Tompsett
Sent: 11 January 2016 14:13
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Tait reference

The T801 units I have seen in the UK contained a rubidium 10MHz reference (FRS 
form factor) and a synthesizer that could produce several outputs of a nominal 
12,8MHz, but which could be individually offset slightly to allow for precise 
offsetting of the transmitter frequencies by a few Hz for use in a quasi-synch 
PMR system.

On 11 January 2016 at 11:18, Charles Steinmetz <csteinm...@yandex.com>
wrote:

> Adrian wrote:
>
> Are these the references with a rubidium oscillator ? They seem to 
> have
>> similar models with OCXOs etc.
>>
>
> Tait is a manufacturer of mobile communications gear in New Zealand.  
> The
> T801 was part of a discontinued "quasi-synchronous communications system"
> -- a form of simulcasting on the same frequency by transmitters at 
> different locations, to fill in dead spots.  Tait's application was 
> utility and public service mobile radios (not radio broadcasting, 
> where this scheme has also been used).  Here is Tait's basic description:
>
> The Tait Quasi-Synchronous Communication System works by broadcasting
>> simultaneously from several transmitters on the same frequency. The 
>> transmitters then operate as a single transmitter giving superior coverage.
>>
>> A Tait T801 Frequency Referenct Module acurately maintains the 
>> frequency of the transmitters at each site.
>>
>> Where required, the T801 allows small frequency offsets to prevent 
>> the occurrence of static nulls in the overlap area.
>>
>> The T801 module may be driven from one of a number of frequency 
>> references, such as:
>> -- Rubidium frequency standard
>> -- Broadcast frequency standard
>> -- Oven Controlled Crystal Oscillators (OCXOs)
>> -- GPS Caesium Clock
>>
>
> This suggests that the T801 does not have an internal frequency 
> reference, but rather requires a precision external reference to 
> function.  (It has a jack labeled "INTERNAL STD OUTPUT," but that may 
> simply be a reference that is derived from the external standard, or a 
> backup crystal oscillator to keep the transmitter more or less on 
> frequency if the external reference signal is lost.)
>
> Best regards,
>
> Charles
>
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 
Stephen Tompsett
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Re: [time-nuts] Tait reference

[Stephen Tompsett]

The T801 units I have seen in the UK contained a rubidium 10MHz reference
(FRS form factor) and a synthesizer that could produce several outputs of a
nominal 12,8MHz, but which could be individually offset slightly to allow
for precise offsetting of the transmitter frequencies by a few Hz for use
in a quasi-synch PMR system.

On 11 January 2016 at 11:18, Charles Steinmetz 
wrote:

> Adrian wrote:
>
> Are these the references with a rubidium oscillator ? They seem to have
>> similar models with OCXOs etc.
>>
>
> Tait is a manufacturer of mobile communications gear in New Zealand.  The
> T801 was part of a discontinued "quasi-synchronous communications system"
> -- a form of simulcasting on the same frequency by transmitters at
> different locations, to fill in dead spots.  Tait's application was utility
> and public service mobile radios (not radio broadcasting, where this scheme
> has also been used).  Here is Tait's basic description:
>
> The Tait Quasi-Synchronous Communication System works by broadcasting
>> simultaneously from several transmitters on the same frequency. The
>> transmitters then operate as a single transmitter giving superior coverage.
>>
>> A Tait T801 Frequency Referenct Module acurately maintains the frequency
>> of the transmitters at each site.
>>
>> Where required, the T801 allows small frequency offsets to prevent the
>> occurrence of static nulls in the overlap area.
>>
>> The T801 module may be driven from one of a number of frequency
>> references, such as:
>> -- Rubidium frequency standard
>> -- Broadcast frequency standard
>> -- Oven Controlled Crystal Oscillators (OCXOs)
>> -- GPS Caesium Clock
>>
>
> This suggests that the T801 does not have an internal frequency reference,
> but rather requires a precision external reference to function.  (It has a
> jack labeled "INTERNAL STD OUTPUT," but that may simply be a reference that
> is derived from the external standard, or a backup crystal oscillator to
> keep the transmitter more or less on frequency if the external reference
> signal is lost.)
>
> Best regards,
>
> Charles
>
>
>
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Stephen Tompsett
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Re: [time-nuts] Tait reference

[Charles Steinmetz]

Adrian wrote:

Are these the references with a rubidium oscillator ? They seem to 
have similar models with OCXOs etc.


Tait is a manufacturer of mobile communications gear in New 
Zealand.  The T801 was part of a discontinued "quasi-synchronous 
communications system" -- a form of simulcasting on the same 
frequency by transmitters at different locations, to fill in dead 
spots.  Tait's application was utility and public service mobile 
radios (not radio broadcasting, where this scheme has also been 
used).  Here is Tait's basic description:


The Tait Quasi-Synchronous Communication System works by 
broadcasting simultaneously from several transmitters on the same 
frequency. The transmitters then operate as a single transmitter 
giving superior coverage.


A Tait T801 Frequency Referenct Module acurately maintains the 
frequency of the transmitters at each site.


Where required, the T801 allows small frequency offsets to prevent 
the occurrence of static nulls in the overlap area.


The T801 module may be driven from one of a number of frequency 
references, such as:

-- Rubidium frequency standard
-- Broadcast frequency standard
-- Oven Controlled Crystal Oscillators (OCXOs)
-- GPS Caesium Clock


This suggests that the T801 does not have an internal frequency 
reference, but rather requires a precision external reference to 
function.  (It has a jack labeled "INTERNAL STD OUTPUT," but that may 
simply be a reference that is derived from the external standard, or 
a backup crystal oscillator to keep the transmitter more or less on 
frequency if the external reference signal is lost.)


Best regards,

Charles


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Re: [time-nuts] Tait reference

[Clint Jay]

Thank you Nigel, I've also taken a gamble on one of these units and am
keeping my  fingers crossed that it has a Rb standard in it.

The service manual is most interesting, it looks like I could use one of
the two 'loops' to lock a different OCXO,  with a little tinkering it could
be a very useful unit as there's plenty of space inside for additions and
modifications.
Are these the references with a rubidium oscillator ? They seem to  have
similar models with OCXOs etc.
http://www.ebay.co.uk/itm/111862884745

Hi Adrian,

The T801 first seems to have hit the UK surplus market around  2005/2006, I
was told a batch of a couple of hundred, and units from that  release were
still trickling through until around 2011 at least.
These were released by West Yorkshire Police when updating their UHF
mobile network and did contain rubidium standards.

The T801 contains dual nominal 12.8MHz  synthesisers with very fine
switched preset adjustment for base  station synchronisation. These are
locked to
an  external reference and can accept selected integer frequencies  from 1
to
10Mhz and also 12.8MHz.
If the internal 10MHz rubidium module is fitted and used as the  reference
then a short BNC link is required to couple the internal  reference output
to the external reference input.

These were originally sold on Ebay with particular reference to the
rubidium module, for most purchasers the 12.8MHz synthesiser board would
probably
have been of little interest, so I'm surprised to see no reference to  the
rubidium module with the several recent auctions. This may be due to  lack
of familiarity on the part of the seller but I certainly wouldn't want to
take anything for granted without asking.
I'm not sure either if the recent Ebay offerings are tail end leftovers
from that first batch or represent a more recent release, but I have seen a
number of failures with the rubidium modules in those bought between 2005
and 2011.
One at least was physically faulty with others refusing to lock,  either at
time of purchase or subsequently, I have some of the latter still  on the
ever growing "to do" pile.

According to the manual the rubidium module, where fitted,  was originally
a Quartzlock TF4010A, but all units I've seen have been  fitted with FEI
FE5660A modules. This required a degree of modification to  the chassis and
to
the heatsink and the quality of that work is often poor, so  quite likely a
field "upgrade".

The unit also contains a DC-DC convertor to derive the 24 Volt  supply for
the rubidium module from the 13.8 Volt input.
The lock on the front panel is just an ON/OFF keyswitch, if the key is
missing all those I've seen have been left in the ON position but it's
easily
bypassed anyway.

I've tried uploading my scan of the manual to Didier's site but gave  up
after repeated page reset errors, it is now available  here..
http://www.mediafire.com/view/0x5sa7o0s9pgc4s/Tait_T801_Frequency_Reference.
pdf

Regards

Nigel
GM8PZR


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Re: [time-nuts] Tait reference

[paul swed]

What little I can tell is they are telco references so there may be
something good inside OCXO or RB. It looks like it runs on -48VDC from the
ebay pix. Its output could be any of the typical telco references that are
not 5 or 10 MHz. These are pure guesses. The Price seems reasonable.
Good luck
Paul
WB8TSL

On Sun, Jan 10, 2016 at 6:48 PM, Adrian Godwin  wrote:

> Are these the references with a rubidium oscillator ? They seem to have
> similar models with OCXOs etc.
>
> http://www.ebay.co.uk/itm/111862884745
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Re: [time-nuts] Tait reference

[Bob Camp]

Hi

Unless we are looking at different auctions, that one appears to want 13.8 V at 
<= 5A
as the supply. 

The BNC’s are also a fairly rare item in the Telco inventory (but not unheard 
of).

If I had to bet, I’d say it’s a piece of mobile video gear. I would not bet 
anything over
about a nickel on that being correct. It’s very much a mystery item other than 
possibly 
having an offset frequency translation function. 

Bob

> On Jan 10, 2016, at 8:35 PM, paul swed  wrote:
> 
> What little I can tell is they are telco references so there may be
> something good inside OCXO or RB. It looks like it runs on -48VDC from the
> ebay pix. Its output could be any of the typical telco references that are
> not 5 or 10 MHz. These are pure guesses. The Price seems reasonable.
> Good luck
> Paul
> WB8TSL
> 
> On Sun, Jan 10, 2016 at 6:48 PM, Adrian Godwin  wrote:
> 
>> Are these the references with a rubidium oscillator ? They seem to have
>> similar models with OCXOs etc.
>> 
>> http://www.ebay.co.uk/itm/111862884745
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