[time-nuts] Freq STD

[Jan Boutsen]

 
 
 
The GR group is looking for a particular AN .  K1LKY comes up with a list:
 
https://www.ietlabs.com/genrad_history/historic_appnotes
 
This particular (old) AN might be an interesting read:
 
http://www.ietlabs.com/pdf/GR_Appnote/A68%20Lewis,%20Freq.%20
 &%20Time%20Standards.pdf
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[time-nuts] Re: Z3801A Receiver Replacement

[Art Sepin]

Robert,

> Is it dead because of Week-Roll over limits or something else?

It is a Week Roll-Over limit. In a working receiver, the time should be correct 
with  3-D fix (min) but the date will be wrong. Some VP and UT+ Oncore 
receivers may have failed but we have found that to be very rare.

Art

P.S. We use SafeLinks protection for our e-mail so it adds many additional 
characters while the mail is being tested for virus, etc. in it's sand box.

-Original Message-
From: Robert DiRosario  
Sent: Tuesday, June 22, 2021 1:49 PM
To: time-nuts@lists.febo.com
Subject: [time-nuts] Re: Z3801A Receiver Replacement

Does this effect All Z3801As?
I have one of these:
https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.realhamradio.com%2FGPS_Frequency_Standard.htmdata=04%7C01%7Cart%40synergy-gps.com%7C9aec8b93f8564034a80a08d935c8ce5c%7Cc81f9fdec0e04d8c95779afaa0cad9ed%7C1%7C0%7C637599958847941854%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000sdata=N%2Fv%2B8URtNzXTNriy92U9kAuYLDhIufaHIq2%2BClC5qC8%3Dreserved=0
I picked up a power supply and antenna for it but  haven't done anything with 
it yet.

 > I have a HP Z3801A with a dead GPS receiver.
Is it dead because of Week-Roll over limits or something else?

Robert


On 06/21/2021 11:54 PM, Art Sepin wrote:
> Hi Fred,
>
> I apologize if the following smells overtly commercial; it's only intended to 
> answer your questions and explain where we are in the process of producing 
> GPS replacement products for legacy timing instruments.
>
> The 6 and 8 channel Motorola VP and 8 channel UT+ will not work as 
> replacements. Those products have also reached their 1024 Week-Roll Over 
> limits. The HP Z3801A and Z3805A products only respond to 6 channel commands 
> and produce 6 channel reply messages.
>
> We have developed single-board clones for the Motorola VP and UT+ products, 
> as drop-in replacements, that are lower in cost than Synergy's 2-board 
> Adaptor Board products (Shooting for dropping to less than $190 if component 
> prices don't go even higher!). The SSR-VP can plug into the HP Z3801A and 
> Z3805A products.
>
> A different part number SSR-VP designed to drop into HP 58503A and an 
> SSR-UT+, designed to drop into HP 58503B products, have also been completed 
> but firmware for those have yet to be tested in actual instruments. With the 
> proper firmware loads, the SSR Drop-In products should be candidates for 
> upgrading many other legacy timing instruments.
>
> We had planned for the single board "Drop-In" products to be available near 
> the end of 2020 but COVID-19 changed things for us. We are now planning a 
> small production run to satisfy folks that have already been in touch with us 
> but we need to complete our boot-loader for firmware updates first. With 
> current work load, I'd estimate 90 - 120 days for HP Z3801A and Z3805A 
> replacements. If you are interested we can put you on our list.
>
> Apologies for the quasi-commercial intrusion!
>
> Art
>
>
> -Original Message-
> From: Frederick Bray 
> Sent: Monday, June 21, 2021 7:21 PM
> To: time-nuts@lists.febo.com
> Subject: [time-nuts] Z3801A Receiver Replacement
>
> I have a HP Z3801A with a dead GPS receiver.  I understand that it is 
> possible to drop in an Oncore VP 8 channel receiver as a replacement -- not 
> withstanding the fact that the Z3801A will only see six channels.
>
> I see that Motorola R5122U1154 8 channel receivers are available.  Does 
> anyone know whether this will function in the Z3801A?  I'd like to get it 
> working again.
>
> Thanks.
>
> Fred Bray, KE6CD
>
>
>
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[time-nuts] Re: Z3801A Receiver Replacement

[Magnus Danielson]

Nigel,

On 2021-06-23 11:32, Nigel gm8pzr via time-nuts wrote:
> The receiver fitted to the Z3801A is/was a Motorola 6 channel Oncore VP.
> It should be possible to replace this with a later 8 channel Oncore VP set to 
> run in 6 Channel mode but a copy of Syntac or Tac32 will be needed to change 
> the configuration.It's also possible that an 8 channel Oncore VP obtained as 
> a replacement may not be physically compatible with the Z3801A and some 
> reworking could be required.
> There has been past discussion of this here that will be available in the 
> archives, but I have uploaded a small file to Mediafire, approx 3MB, that 
> contains some relevant information that I've saved in the past...
>
> https://www.mediafire.com/file/7w7moa6rd7kmk9r/OncoreVP_Z3801A.zip/file

Thanks for that set of data. There used to be a wealth of datasheets for
both boards and chips, but that went away. Here is at least some of that
data, which I appreciate.

If people have more of that, it would be nice if we could collect that
and upload on a suitable place.

I also appreciate Art's postings, and would enjoy getting updates on that.

My Z3801A has a failed PSU I think, so that needs to be resurrected. I
have a few others that I would wish would get operational.

Cheers,
Magnus
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[time-nuts] Re: PRS-10 heatsink design

[Bob kb8tq]

Hi

All of these small “telecom” Rb’s suffer the same way. The form factor is 
similar
and they all dump a lot of heat out the baseplate. None of them do well with a 
“down facing” simple heatsink

“Simple” answers:

1) Use a fan / forced air. That’s how they typically where used in most (but not
all …) telecom gear. 

2) Go off to any of the many online heatsink outfits and buy a chunk of 
extrusion
better suited to the task. Even with 30 mm fins, down facing isn’t great.

3) Flip the unit so the fins face up

Best is still going be fins that are up/down in the vertical plane (if that 
makes
any sense at all …) and get good airflow from bottom to top. 

If you go with a fan, be careful to isolate it a bit. Rb’s do have vibration 
sensitivity. 
One plus with a fan is that you can servo it to maintain accurate temperature. 

Bob

> On Jun 23, 2021, at 7:00 AM, Dana Whitlow  wrote:
> 
> I mount my PRS-10 vertically (so that the channels between the fins are
> vertical),
> with the connector on top.  This orientation was chosen simply for best
> access to
> the connector, but yields heat sink temperatures down around 45C to 50C.
> The
> unit is open and fully exposed to the air.  I run it at 24Vdc.
> 
> The open mounting is obviously best for natural convective cooling, but does
> leave the stability somewhat vulnerable to ambient temperature variations,
> drafts, etc, although I've not had obvious problems with this.
> 
> If you want to combine good cooling with low dependence on rapid variations
> in ambient temperature, I suspect the best way is to interpose a very thick
> aluminum (or copper) block between the heatsink flange of the PRS-10 and
> the heatsink.  The block will add minimal thermal resistance, but will
> serve as
> a thermal lowpass filter.  The downside to this is that full warmup of the
> PRS-10
> will take longer.
> 
> Dana
> 
> 
> On Wed, Jun 23, 2021 at 2:05 AM James Wilson  wrote:
> 
>> My limited experience with the factory heatsink for the PRS-10 has left me
>> pretty unsatisfied. It seems ok for brief bench evaluation but not for
>> permanent enclosure installation. Reported unit temps are in the 70 - 75 °C
>> range with it sitting on a bench in a 25 °C room. It needs to be turned on
>> its side or upside down for any convection to take heat away, or for fans
>> to be directed at the fins. There are no side or top screw holes on the
>> PRS-10 so you can’t mount it in that orientation. Has anyone found or built
>> a better heatsink that can use active cooling?
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[time-nuts] Re: PRS-10 heatsink design

[Dana Whitlow]

I mount my PRS-10 vertically (so that the channels between the fins are
vertical),
with the connector on top.  This orientation was chosen simply for best
access to
the connector, but yields heat sink temperatures down around 45C to 50C.
 The
unit is open and fully exposed to the air.  I run it at 24Vdc.

The open mounting is obviously best for natural convective cooling, but does
leave the stability somewhat vulnerable to ambient temperature variations,
drafts, etc, although I've not had obvious problems with this.

If you want to combine good cooling with low dependence on rapid variations
in ambient temperature, I suspect the best way is to interpose a very thick
aluminum (or copper) block between the heatsink flange of the PRS-10 and
the heatsink.  The block will add minimal thermal resistance, but will
serve as
a thermal lowpass filter.  The downside to this is that full warmup of the
PRS-10
will take longer.

Dana


On Wed, Jun 23, 2021 at 2:05 AM James Wilson  wrote:

> My limited experience with the factory heatsink for the PRS-10 has left me
> pretty unsatisfied. It seems ok for brief bench evaluation but not for
> permanent enclosure installation. Reported unit temps are in the 70 - 75 °C
> range with it sitting on a bench in a 25 °C room. It needs to be turned on
> its side or upside down for any convection to take heat away, or for fans
> to be directed at the fins. There are no side or top screw holes on the
> PRS-10 so you can’t mount it in that orientation. Has anyone found or built
> a better heatsink that can use active cooling?
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[time-nuts] Re: Z3801A Receiver Replacement

[Nigel gm8pzr via time-nuts]

The receiver fitted to the Z3801A is/was a Motorola 6 channel Oncore VP.
It should be possible to replace this with a later 8 channel Oncore VP set to 
run in 6 Channel mode but a copy of Syntac or Tac32 will be needed to change 
the configuration.It's also possible that an 8 channel Oncore VP obtained as a 
replacement may not be physically compatible with the Z3801A and some reworking 
could be required.
There has been past discussion of this here that will be available in the 
archives, but I have uploaded a small file to Mediafire, approx 3MB, that 
contains some relevant information that I've saved in the past...

https://www.mediafire.com/file/7w7moa6rd7kmk9r/OncoreVP_Z3801A.zip/file

As well as data sheets and engineering notes this file includes comments on 
configuring the 8 channel receiver as 6 channel and also regarding the need to 
power cycle the Oncore VP, and hence the Z3801A, rather than leaving them to 
run unattended for years.
Another good source of information on the Z3801A is the Real Ham Radio web site.

Nigel GM8PZR


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[time-nuts] PRS-10 heatsink design

[James Wilson]

My limited experience with the factory heatsink for the PRS-10 has left me 
pretty unsatisfied. It seems ok for brief bench evaluation but not for 
permanent enclosure installation. Reported unit temps are in the 70 - 75 °C 
range with it sitting on a bench in a 25 °C room. It needs to be turned on its 
side or upside down for any convection to take heat away, or for fans to be 
directed at the fins. There are no side or top screw holes on the PRS-10 so you 
can’t mount it in that orientation. Has anyone found or built a better heatsink 
that can use active cooling?
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