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EB4APL | 24 May 2013 01:44
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FE-5680A control programs

Hello,

Since I bought my FE-5680A (10 MHz, 1 PPS variety), I have been 
collecting control programs for it and keeping then in reserve.  Now 
that I'm going to box it with a distribution amp I tried some of them, 
first of all to adjust the frequency against the GPS.  I used Bob 
Campbel's VK4XV  "Fe5680Calibrator.exe" with good results.  I have other 
programs which interrogates the device and shows the hex dumps, but I 
would like to know if there is a windows program that allows to send 
other that the offset related commands to the device and get the 
responses not in hex but translated to plain language. In fact I don't 
know if there are housekeeping commands for reading thinks like the lock 
status or the lamp voltage like the analog outputs of the  FRS-C and others.

Thanks in advance,
Ignacio EB4APL
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paul swed | 23 May 2013 20:00
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EG&G TS-RFS telcom RB

Hello to the group I obtained 2 of these units at the last MIT flea. Both
not working correctly.
Virtually no documentation on the internet. I recall that 2 years ago
someone else asked EGG info also and no real responses.
That said I can tell you a few things. There is a diagram on the unit that
shows the 16 connections. Its accurate.
+24 requires up to 1.5A cold and drops to 300-400 ma hot
+5 for the synthesizer draws a constant 300 ma
It seems you can start the RB up without the +5 RB and synthesizer are
quite separate.

The EGGs seem to have a fair amount of reserve RB gas in the lamp. The two
units I have have high lamp voltages even though they were mid 1990s.

Both units were bad. The problem is the 470 uf  <at> 25 V 15 volt bypass caps
and a regulator cap 270 uf  <at> 16V. It literally fell apart when I was
removing it. One of the 470 UFcaps read 1UF esr 2.6 ohms
Replaced with high temp 50 V equivalents and both units startup and
automatically lock in about 5 minutes. Changing these caps also put the
units back into specification for stability.

So there you have it the total EG&G cookbook of RBs.
Good luck and they do seem to be a fine unit.
Regards
Paul.
WB8TSL
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steve gunsel | 23 May 2013 15:30
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Re: time-nuts Digest, Vol 106, Issue 110

Bill,

I have an HP3335 and often use it. I hope mine will keep running!
I'm sure there are others who could make good use of one of them.

Steve, N8MYA

At 01:06 AM 5/23/2013, you wrote:
>Send time-nuts mailing list submissions to
>         time-nuts@...
>
>To subscribe or unsubscribe via the World Wide Web, visit
>         https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>or, via email, send a message with subject or body 'help' to
>         time-nuts-request@...
>
>You can reach the person managing the list at
>         time-nuts-owner@...
>
>When replying, please edit your Subject line so it is more specific
>than "Re: Contents of time-nuts digest..."
>
>
>Today's Topics:
>
>    1. Re: 9390 GPS RX (Tom Knox)
>    2. TrueTime TL-3 WWV Receiver (Majdi S. Abbas)
>    3. Re: Extron ADA 6 as 1/5/10 MHz DA (Charles P. Steinmetz)
>    4. Re: Net4501's cheap... (Jim Sanford)
>    5. Downsizing dilemma, HP 3335A (Bill Hawkins)
(Continue reading)

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Majdi S. Abbas | 22 May 2013 20:45

TrueTime TL-3 WWV Receiver


	Does anyone happen to have a manual, or at least a pinout
for the 8 pin mini-DIN serial port?  It doesn't appear to be one of
the common mini-DIN serial arrangements.

	If you do have a manual, I'm really just interested in the
pinout and serial command set.  

	Any help greatly appreciated,

	--msa
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Charles P. Steinmetz | 22 May 2013 19:59

Extron ADA 6 as 1/5/10 MHz DA

Following the recent discussion of using the Extron ADA 6 as a 
distribution amplifier for 1/5/10 MHz reference signals, I dug out 
the schematic of the amplifiers and typed up my notes re: 
modifications (see attached).

Note that the ones I have are "plain" ADA 6's, not "MX" or 
"MX-HV."  I do not know if the MX or MX-HV units use this circuit or, 
if they do, if the component numbers are the same.  However, the 
gain-switching circuitry is present on the "plain" ADA 6 PC cards 
(but the switch itself is not), which leads me to believe that at 
least the MX version was built with this same card.

There may be other Extron video DAs that use this circuit -- in 
particular, models that have a PC card parallel to the rear panel and 
mounted to it by the BNC connectors may do so.

There is another, discrete design that Extron apparently produced at 
the same time, one example of which is the ADA 3 180.  This design 
cannot drive 50 ohm loads to +13dBm (1 Vrms) without severe 
distortion (negative peak clipping), so you need to attenuate the 
typical 1 Vrms input signal 6 dB to stay out of 
clipping.  Unfortunately, there is no easy way to modify this design 
to drive +13dBm into 50 ohms (and, IMO, there is a lot not to like 
about it for any use, including RGB video).  I have a schematic of 
that circuit, too, if anyone needs it.

Best regards,

Charles
(Continue reading)

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Brucekareen | 22 May 2013 17:54
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Distribution Amp for Thunderbolt and David Partridge's Divider Box

A year or so ago I modified an Extron  ADA 6 300MX TV  distribution 
amplifier to house one of David Partridge's divider boards  along with a 1 MHz 
sine-wave filter and a 10 MHz to 100 MHz multiplier after  Luciano 
Paramithiotti's design.  I use the rear BNC connectors to  distribute 1, 10, & 100 MHz 
sine-waves.  The synch channel was modified  to distribute 1 MHz square-waves.

On the front panel are BNC connectors for 1, 10, & 100 MHz sine-waves;  1 
MHz & 5 MHz square-waves; and an output with rotary-switch-selected  1, 10, 
100, 1 kHz, 10 kHz, or 100 kHz square-wave from the Partridge divider  board. 

My ADA 6 300MX unit had conventional resistors on the board so it was  
relatively easy to change them to 50-ohms.  I eliminated the 0.7/1.0 V  switch.  
I found it possible to power the Partridge divider board and 10 to  100 MHz 
multiplier module as well as the distribution amplifier from the  internal 
Extron power supply by adding a 12 V to 5 V inverter module  (bought on 
eBay) and a Murata RFI filter. 

As modified, there is a single 10 MHz input to the assembly, and 5 <at>  1 MHz,  
3 <at>  10 MHz, and 5 <at>  100 MHz outputs on the rear panel.  There are also 5 <at>  1  
MHz square-wave outputs from the former sync section.  Connectors  
corresponding to the DA outputs used internally were removed and the holes  fitted 
with plastic plugs of the correct size.  

To get everything to fit, I had to shift the power supply on the lid.   
While the Extron cases are of very fine mechanical construction, the front and  
rear panels are not well bonded electrically.  I added bonding braids to  
improve the shielding and RF performance.  A nice feature of these units is  
that the front and rear panels can be easily removed for engraving.

I briefly considered trying to add miniature isolation transformers behind
(Continue reading)

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Joseph Gwinn | 21 May 2013 16:20
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Re: Ground loops in measurements?

 time-nuts Digest, Vol 106, Issue 101
> 
> Message: 6
> Date: Mon, 20 May 2013 17:16:02 -0400
> From: "Bob Camp" <lists@...>
> To: "'Discussion of precise time and frequency measurement'"
> 	<time-nuts@...>
> Subject: Re: [time-nuts] Ground loops in measurements?
> Message-ID: <5654054C635D47F2A251C902A875F035@...>
> Content-Type: text/plain;	charset="us-ascii"
> 
> Hi
> 
> The braid becomes less effective at lower frequencies due to skin effect.
> Once that happens you have a magnetic loop that is not as effective at
> rejecting signals as a twisted pair. 
> 
> Looking at it another way, the threat signal is induced on the shield
> (braid) and it penetrates to couple to the center conductor. 
> 
> There are a couple of other ways to look at it, they all ultimately come
> back to the same point. There are a few other odd things that happen as well
> as you drop frequency, none of them really very helpful for moving signals. 
> 
> ---------------
> 
> Now - is it actually a problem or not? As always, that depends. Most of the
> nasty stuff in a 1 pps is in the edges. That energy (with a fast edge) is
> nicely captured by the coax. The low frequency stuff is not captured as
> well, but it also doesn't couple all that well either. Making a transformer
(Continue reading)

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Tom Clifton | 21 May 2013 15:57
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Absolutely unbelievable

Never guess how long ago I purchased a pair of these things...   I thought that everybody would have
figured this out by now and would be using a 2.6 kernel
 
 
 
FIELD SERVICE BULLETIN
FSB #:098-50620-059 Date: August 3rd, 2012
______________________________________________
System: SyncServer S2xx Series Network Time Servers

 
Product Identity: NTP Servers
______________________________________________
NOTE: Find a copy of this FSB in Support section of our website at http://www.symmetricom.com/.
Behavior: Affects all S200 | S250 | S250i SyncServer Series Units
For a SyncServer S2xx Series SyncServer that remains running continuously for 497 days, it will likely
reboot on day 497 or possibly the unit’s display or key pad may become nonfunctional on that day.
 
Explanation:
The issue is in relation to the Linux 2.4 kernel being used inside the S2xx Series SyncServer. This known
Linux issue can cause unexpected behavior of the SyncServer S2xx Series when uptime reaches 497
Days.
 
The 2.4 kernel computes the system uptime based on the internal jiffies counter, which counts the time
since boot in units of 10 milliseconds (100 Hz), or jiffies. This counter is a 32-bit counter, which has a
maximum value of 2^32, or 4,294,967,296. When the counter reaches this value (after 497 days, 2
hours, 27 minutes, and 53 seconds, or approximately 16 months), it wraps back around to zero and
continues to increment. When the jiffies counter wraps, unexpected side effects described above in the
Behaviors section may be observed
(Continue reading)

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Mark C. Stephens | 21 May 2013 12:42
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9390 GPS RX

Hello Fellow time nuts,

I received a Datum 9390 GPS receiver I bought off eBay today. It had a PSU fault and I am running it off a bench
supply until I can get the PSU working again. All the PSU does is supplies 28V so I can probably adopt a more
recent supply to fit if I can't fix the old one. I pulled the PSU apart and so far found a blown triac. There is
bound to be more 'things' blown but I want to see if it's worth repairing first. I mean, it's not much use
repairing something that proves to be useless?

Funnily enough in the back of the Manual binder was a second manual. A service Manual for a Trimble 5000A
GPS/TIME frequency monitor. I'll scan it if anyone needs it?

This particular 9390 is an odd Chap, doesn't look at all like picture in the supplied manual. http://www.vk2hmc.net/blog/wp-content/uploads/2013/05/9390-fr.jpg

When I opened it up, http://www.vk2hmc.net/blog/wp-content/uploads/2013/05/9390-insides.jpg  I saw
an Efratom FRK! http://www.vk2hmc.net/blog/wp-content/uploads/2013/05/frk.jpg

I am having a bit of problem identifying the GPS module. It says Trimble navigation on the board: http://www.vk2hmc.net/blog/wp-content/uploads/2013/05/gps-bd.jpg
I measured the antenna Jack for the expected 15V normally on a Datum 9390, but found it was 5.1 volts.
I could not get rid of the Antenna feed error until I put a 50 ohm terminator on it. I tried higher values
(75-180R) but the only value that cleared the feed error was 50 ohms. So I used a BNC 'tee' and terminated the
output of the GPS distribution amp to the 9390. I fear this GPS RX requires an antenna with a down-convertor
-or- a whacking great L1 signal. I always thought the 9390 had a Trimble svee6 module in them. But this one's
positively ancient.
I have entered my approximate co-ordinates to see if it finds any birds but so far no luck.

If you know anything about this GPS board, please leave me a message?

The interface convertor from the Trimble to the Datum:
http://www.vk2hmc.net/blog/wp-content/uploads/2013/05/gps-bd-if.jpg is labelled "Datum TANS interface".
(Continue reading)

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Hal Murray | 21 May 2013 08:47

Re: OCXO shock protection


tvb@... said:
> If the quake is strong, the temporal acceleration is on the order of 0.1 g.
> See: http://en.wikipedia.org/wiki/Peak_ground_acceleration 

There is a long tail on that curve.  One could also define "strong" as 1 g.

The wiki page (above) lists 3 events with PGA above 2 g and several more 
above 1 g.  I remember a USGS report about an event in northern California 
showing a big bulldozer on its side.  The punch line was that the local PGA 
was over 1 g.  (Bulldozers have a low center of gravity.  It's hard to tip 
them over.)

Those are really nasty events.  Distance from the quake (aka luck) is also 
very important.  If you are near one of them you will probably be worrying 
about things other than your OCXO.  (Iterate for what "near" means.)

----------

> Your OCXO will be fine, unless it falls on the floor.

I agree that falling on the floor is the main thing to worry about.

--

-- 
These are my opinions.  I hate spam.
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J.D. Schoedel | 21 May 2013 06:26
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display on sale

Most of  you like to DIY, but this might be of interest to some.
http://www.symmetricom.com/lp/gbu/email/time-display-promo-landing-page/?emailid=GBU078_NTD_Promo_ProdPg&lead_source=Web

J.D.
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Gmane