Re: [time-nuts] FE-5680A performance
I did something similar- momentary contact of +15V supply with one of the other pins- might have been the +5 Vin, or another signal. The 75ACT240 became very hot. I ordered a replacement 75ACT240 part, swapped it in, and the unit seems to work fine now. Note this is the 0.3" wide device, DigiKey p/n 74ACT240SC-ND. Confusingly, that part in 20-pin SOIC is made in two different body widths: 0.209" / 5.3 mm and 0.295" / 7.5 mm.
This photo shows the board with the smoked chip removed (U503 at upper left), before I installed the replacement
https://picasaweb.google.com/lh/photo/mF9WSGlEQjA8MqHhbPOJRdMTjNZETYmyPJy0liipFm0?feat=directlink
-john
-------Original Message-------
From: EB4APL eb4apl@cembreros.jazztel.es
To: time-nuts@febo.com
Subject: Re: [time-nuts] FE-5680A performance
Sent: 05 Jan '12 11:37
I found it, I used the +15 V of my triple output supply to power the
pin 4, +5 V input. A 75ACT240 popped up and who knows the health of the
other things.
Wish me luck,
Ignacio, EB4APL
El 05/01/2012 18:54, EB4APL wrote:
I agree, I've seen it in a Tek 7623A with the storage on, it is quite
difficult without it.
Regards,
Ignacio, EB4APL
PD. Just trying to verify this I made some error and let the magic
smoke leave the unit. It is still smelling ...
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.
John,
You are not alone in this trip. Another member of this list tells me
that he connected the power to the lock indicator pin when he received
his unit and he was eager to test it. His 74ACT240 also got cooked but
the rest of the unit continued working normally.
Well, mine seems to have the same good luck. It lits the Rb lamp, the
temperature controller takes the normal current, the oscillator sweeps
back and forth and then the unit LOCKS!. I only have missing the Lock
indicator and the PPS.
And to continue the original test, I checked the PPS this time at the
input of the buffer (74ACT240 pin 2) and it is there but very difficult
to see without a storage or digital scope, the duty cycle is too low.
Anyway the trigger light is a tell tale.
And thank you for your tip about the chip type, I have to order one and
replace it because I want the PPS and the lock indicator, and maybe some
other buffers are used inside for minor functions.
BTW, maybe the units who lack the PPS have this output damaged, because
some info list this pin as power input and it seems to be true but in
other FE-5680 variants. Who knows why FE designed so different units
with the same number.
Best Regards,
Ignacio, EB4APL
On 05/01/2012 21:10, beale wrote:
I did something similar- momentary contact of +15V supply with one of the other pins- might have been the +5 Vin, or another signal. The 75ACdT240 became very hot. I ordered a replacement 75ACT240 part, swapped it in, and the unit seems to work fine now. Note this is the 0.3" wide device, DigiKey p/n 74ACT240SC-ND. Confusingly, that part in 20-pin SOIC is made in two different body widths: 0.209" / 5.3 mm and 0.295" / 7.5 mm.
This photo shows the board with the smoked chip removed (U503 at upper left), before I installed the replacement
https://picasaweb.google.com/lh/photo/mF9WSGlEQjA8MqHhbPOJRdMTjNZETYmyPJy0liipFm0?feat=directlink
-john
-------Original Message-------
From: EB4APLeb4apl@cembreros.jazztel.es
To: time-nuts@febo.com
Subject: Re: [time-nuts] FE-5680A performance
Sent: 05 Jan '12 11:37
I found it, I used the +15 V of my triple output supply to power the
pin 4, +5 V input. A 75ACT240 popped up and who knows the health of the
other things.
Wish me luck,
Ignacio, EB4APL
El 05/01/2012 18:54, EB4APL wrote:
I agree, I've seen it in a Tek 7623A with the storage on, it is quite
difficult without it.
Regards,
Ignacio, EB4APL
PD. Just trying to verify this I made some error and let the magic
smoke leave the unit. It is still smelling ...
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.
Hi Chris,
The documentation I have says pin 6 is "N/C" but it looks like there is a
way to extract a usable PPS but I think I'm going to need and LC filter,
some op amps and a one-shot and a TTL level driver. My guess is that pin
6 is either some kind of engineering test/diagnostic signal not intended
to use used or the signal is an accident.
I have two of the older generation. Here the ONLY output is a 1PPS, which
is divided by a fixed 2^23 from the internal DDS-generated frequency
(8.3xxxMHz). It is not possible to get both 10MHz and a 1PPS at the same
time. On the other hand the 8.3xxxMHz is tunable over many MHz.
(One of the units is also suffering from a mishap. 15V connected to the
1PPS output did some damage.)
--
Björn
On Thu, Jan 5, 2012 at 1:48 PM, bg@lysator.liu.se wrote:
Hi Chris,
The documentation I have says pin 6 is "N/C" but it looks like there is a
way to extract a usable PPS but I think I'm going to need and LC filter,
some op amps and a one-shot and a TTL level driver. My guess is that
pin
6 is either some kind of engineering test/diagnostic signal not intended
to use used or the signal is an accident.
I have two of the older generation. Here the ONLY output is a 1PPS, which
is divided by a fixed 2^23 from the internal DDS-generated frequency
(8.3xxxMHz). It is not possible to get both 10MHz and a 1PPS at the same
time. On the other hand the 8.3xxxMHz is tunable over many MHz.
(One of the units is also suffering from a mishap. 15V connected to the
1PPS output did some damage.)
My guess is that these all have the same part numbers because the hardware
is the same. But one chip is a CPLD which might have some very different
programming depending on what the customer needed I see some components
where never installed on my unit, so it maybe more than just programming.
--
Björn
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.
--
Chris Albertson
Redondo Beach, California
Chris,
On Thu, Jan 5, 2012 at 1:48 PM, bg@lysator.liu.se wrote:
Hi Chris,
The documentation I have says pin 6 is "N/C" but it looks like there
is a
way to extract a usable PPS but I think I'm going to need and LC
filter,
some op amps and a one-shot and a TTL level driver. My guess is that
pin
6 is either some kind of engineering test/diagnostic signal not
intended
to use used or the signal is an accident.
I have two of the older generation. Here the ONLY output is a 1PPS,
which
is divided by a fixed 2^23 from the internal DDS-generated frequency
(8.3xxxMHz). It is not possible to get both 10MHz and a 1PPS at the same
time. On the other hand the 8.3xxxMHz is tunable over many MHz.
(One of the units is also suffering from a mishap. 15V connected to the
1PPS output did some damage.)
My guess is that these all have the same part numbers because the hardware
is the same. But one chip is a CPLD which might have some very different
programming depending on what the customer needed I see some components
where never installed on my unit, so it maybe more than just programming.
No, there are two different generations. The older based on 50.xxx MHz,
the newer on 60.0MHz (?) The older has a lot of stacked daughtercards on
the digital side. There are many differend sub-versions of these as well.
The newer generation seem to be one clean PCB. Look for picture links in
the recent archives.
--
Björn
You've had more progress than I did, I don't get anything out of pin 6. I
did see the levels toggle, but that was about it. On various websites I
read to get exactly 1pps, you need a programmable 5680 because it needs to
be set to something like 8.388MHz (2^23) to divide down properly. I suspect
you may not be able to get both; 10MHz and 1pps.
Bob
----- Original Message -----
From: "beale" beale@bealecorner.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Thursday, January 05, 2012 12:46 PM
Subject: Re: [time-nuts]FE-5680A performance - 1 PPS output issue
I think there is something funny about the 1 PPS output on pin 6 from the
currently available cheap FE-5680A units. I have three of these units. On
one unit, on one occasion, I did observe a logic-level 1 PPS pulse, exactly
1 microsecond wide. But after a power cycle it never came back, although
the unit indicates a locked condition, and is apparently working. The other
two units also seem to work (10 MHz output OK, lock OK) but I have never
seen a 1 PPS signal on pin 6 from them. My Tek TDS-210 is easily capable of
triggering on and displaying a 1 usec pulse. Is it possible the pulse
appears only after a RS-232 command, or after some other special condition?
-------Original Message-------
From: David davidwhess@gmail.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] FE-5680A performance
Sent: 05 Jan '12 07:49
On Thu, 05 Jan 2012 01:44:13 -0800, Hal Murray
hmurray@megapathdsl.net wrote:
nothing
on that pin but milivolt level sine wave of about 60MHz. I can't set
the
scope to show any hint of a PPS ...
I do have a 465. You should be able to see a 1 uSec PPS.
60MHz is about a 6nS rise time and is easily fast enough to see it.
Now turn up the Intensity until you can see the pulse. It might help to
turn
down the room lights.
This is the problem. With a 1 second repetition rate, the brightness
is going to be very low.
The old ways of viewing such a low repetition rate signal include
using a hood or dark room, special CRT phosphors, photographic film,
MCP (micro channel plate) intensified CRTs, and of course analog
storage and later digital storage.
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.
On Thu, Jan 5, 2012 at 8:45 PM, Robert Benward rbenward@verizon.net wrote:
You've had more progress than I did, I don't get anything out of pin 6. I
did see the levels toggle, but that was about it. On various websites I
read to get exactly 1pps, you need a programmable 5680 because it needs to
be set to something like 8.388MHz (2^23) to divide down properly. I suspect
you may not be able to get both; 10MHz and 1pps.
I just got one of the $38 units on eBay. It has both 10MHz and 1PPS.
My HP5328 counter only works at the uSecond level but as far as it
can tell my FE5380 tracks my GPS.
The new fe5380 can be programmed but only over a very small range
right around 10MHz.
When we talk about fe5380 there are enough different types that are so
very different but all have the same part numbers. We need a name
for the types and a why a user can find the name of the unit he has.
a Wiki would be great. Is there a FE5380 article yet on wikipeadia?
Chris Albertson
Redondo Beach, California