Re: Suffering from RIFA anxiety!
I have seen a handful fail between work (4 hospital IT group) and home.? All had been in 120 volt service.? If I see any cracking, that cap is removed and replaced.? If there is no cracking I have been known to risk it for a while.??
--
Thanks,
Randy
randy.ab9go@...
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Re: Suffering from RIFA anxiety!
On 9/11/22 11:53, Chuck Harris wrote: Mostly the failure rate of RIFA paper dielectric safety
capacitors, with clear (yellow) epoxy potting, is related
to how large the difference is between their design failure
voltage, and the voltage applied.
In other words, for older capacitors:
If you use a 250VAC RIFA cap on 240VAC mains, failure is
all but assured.
If you use a 250VAC RIFA cap on 120V mains, you will likely
never see a failure. That's nowhere near true in the field, unfortunately. I've replaced two 250VAC RIFA capacitors run on 120V in the past week alone. These blow up *all the time*. Storage in a humid environment dramatically accelerates the failure of RIFAs. Or so says my 40 years of experience as an engineer, with never
seeing a single RIFA capacitor failure on 120VAC. You've been lucky. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
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Re: HP 5342A Microwave Counter and 5344A Source Synchronizer for sale
This is a reminder that the rare HP 5344A Source Synchronizer is still available.
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Details are here:
Note, the HP 5342A is not for sale at this time.
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Re: Brand New Storage CRT for Hewlett Packard HP 141T Spectrum Analyzer
Reminder that the brand new CRT for the 141T is still available.
Double-boxed and ready to ship or pick up locally in San Diego, CA or Los Angeles. (contact me off list for local pickup)
US$167.00 plus shipping. PayPal, check (must clear before shipping), or cash okay for local pickup.
More details and pictures here:
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Re: Suffering from RIFA anxiety!
"Dave McGuire" <mcguire@...> writes: Actually I don't think we've run into any of those at LSSM, and I've
not had any fail in my own test equipment either. I guess I've gotten
lucky there.
Though most people say that the big problems with Schaffners show up
when an instrument that had a previous life in a 115V country is moved
to a 230V country.
We should probably adopt a replace-on-sight policy for those at LSSM,
but most of the hardware on exhibit there mostly predates the existence
of IEC connectors, and thus the all-in-one line entry modules. Thanks for the input Dave. If you do ever encounter these and develop a strategy for dealing with them, I'd be curious to hear it. The procedure for replacing standalone RIFAs seems straightforward to me: use a film safety cap with the closest mechanical and electrical compatibility. It's often not possible to find something with the exact same form factor, but it's easy to work around this by bending the leads a bit. Dealing with Schaffner filters is a bit more complicated in my opinion. The general recommendation appears to be to replace them with a mechanically-compatible modern equivalent. However, Kemet (who I believe purchased the safety cap line of RIFA) still produces these metallized paper (MP) in epoxy capacitors (eg the PME271: ). To my knowledge Kemet has never acknowledged this issue so I don't think we can say these newer caps are any better than the old ones. I know of one individual who opened a modern Schaffner and found film caps, but one data point isn't enough to say for sure that modern Schaffners always avoid these MP caps. I've reached out to Schaffner and will report back if I hear, but I sort of doubt they'll disclose this information. I may start purchasing these in pairs to open one up as a last resort. One thing that makes me a bit pessimistic and reluctant to assume Schaffner is using better caps is that I don't get the impression that most manufacturers, test equipment companies, or end consumers actually care about this. The onset of the failure mechanism is typically more than a decade (often much more), which is beyond the designed service life of most equipment. There are some consumers (apart from us), who probably do care. For instance, I get the impression that universities often hold onto equipment for a while. But many businesses probably don't expect to get 20 years out of equipment, especially if they expect to replace them with more modern, "better" gear after 10. I'm speculating of course, and would love for people to tell me I'm wrong, but that's my impression. For what it's worth, I've never seen a RIFA or Schaffner failure and I've amassed quite a bit of gear at this point. I'm in 120V land, which helps. I do replace RIFAs, but haven't gotten around to it on every item yet. That low failure rate doesn't assuage me much since I'd like to get as many decades of use out of these pieces as possible. I'm younger than nearly every instrument I own, so ideally that's quite a few decades. Matt
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Re: Suffering from RIFA anxiety!
Mostly the failure rate of RIFA paper dielectric safety capacitors, with clear (yellow) epoxy potting, is related to how large the difference is between their design failure voltage, and the voltage applied. In other words, for older capacitors: If you use a 250VAC RIFA cap on 240VAC mains, failure is all but assured. If you use a 250VAC RIFA cap on 120V mains, you will likely never see a failure. Or so says my 40 years of experience as an engineer, with never seeing a single RIFA capacitor failure on 120VAC. -Chuck Harris On Sun, 11 Sep 2022 06:02:48 -0700 "Precaud via groups.io" <jbau@...> wrote: I have several 80's-90's HP instruments on the bench, have never seen
a Rifa failure, so I'm curious. Is the failure related to power-on
hours, or number of on-off cycles?
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Hello;
Is your dongle an FTDI chip inside? I've had issues with drivers and fake/counterfeit chips
On Saturday, September 10, 2022, si_emi_01 < wellington@...> wrote: Hi, ? If 28dBi isn¡¯t enough gain, you can increase it with an in-line preamplifier. The Z3801A Manual (page 2-4), even mentions it for long cable runs ¨C including cascading them for long runs and lossy cables. ? Vendors used to make amplifiers for CATV and Satellite TV. They are still available dirt cheap - $7.95 USD on ePay. They have a frequency range of 950MHz to 2150MHz. ? They have F Connectors - they¡¯re for TV Stuff, right? I just a Male and Female BNC to F Connector adapters. You just patch it in. I have heard of people cascading them too, dumb ¨C where is that signal now in all of this noise? Grin ¨C contradiction, I guess. ? They say it needs 12V minimum to power it. The Z3801A supplied 5V works fine, you just get less gain of course. It doesn¡¯t seem to over current the Z3801A supply either. I¡¯m sure the 75 Ohm to 50 Ohm mismatch VSWR is relatively poor 1.5:1 or more, it does work. ? I don¡¯t know if you would have success with 3.3V though. It may not bias-up with whatever device they are using with their design. Mine is an RCA brand ¨C got it at Walmart a long time ago. ? I have the Amplifier in line (about 10 feet of cable from the Antenna), plus another 10 foot cable connected to my Z3801A RF Port and it does work. I get around 9dB gain at 1575MHz. It does have kind of a crappy Noise Figure specification, but you still get enough gain to make it worthwhile. My antenna is in the house on the second level and I generally see 4 of 6 satellites all of the time. It goes into ¡°Holdover Mode¡± very occasionally. ? Since the same GPS Engine is probably used for the Z3801A and Z3804A, it should have 5V from the Z3804A. It passes the 5V through to the GPS Antenna for its operation. ? I added the in-line Amplifier in early 2004 and it has been operating without incident since then ¨C 19 years. ? I use GPS-Con for the Console on my main computer. I like it. ? ? HP Z3801A Modifications ---------------------------------- I bought my Z3801A in March 2003. I built a -50V Linear Power Supply for it, put that on a UPS. I have seen it pull over 1A for a short period of time when the OXCO is cold until the Outside Blanket is up to temperature. It draws much less than that afterwards. ? I modified it for the RS232 Interface instead of the RS-422 Interface and connected that to a cable with a USB to RS232 Dongle ¨C the Software Driver doesn¡¯t work with the Dongle Chip on it now. Using direct cabling for now. ? I also made a translator followed by a paralleled 74F38 Driver and Pullup plus series Cable termination for the 1PPS Output. That connector is on the Front Panel with a similar translated and buffered 10MHz TTL Signal Connector as well. ? I also added a 7404 to drive an LED for a Front Panel heartbeat indicator. ? ? Does anyone know of a Dongle that works with the Windows 10 Driver? It used to work but now comes up with a message that the Driver and Hardware Dongle are incompatible. ? ? Ross ? ? ? ? Power up the unit and check the antenna connector to ground with a dvm. Believe you will see. 5 V. Good to check. However if the z380X is newer maybe 3.3V. That antenna should work as long as the cables not to long and the antenna has a good view of the sky. 28 db gains not all that much. But may be good enough for your check. Best of luck you are making progress. I see Dave answered is a Motorola Oncore receiver.
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Re: Suffering from RIFA anxiety!
It is related to the number of cracks in
the capacitor case, the relative humidity and the will of the
electron god.
All appear to fail with a lot of smoke, possibly a pop or bang and
the instrument usually still operates.
It is just a fire hazard.
REPLACE them!!
Glenn
On 9/11/2022 9:02 AM, Precaud via
groups.io wrote:
I have several 80's-90's HP instruments on the bench, have never
seen a Rifa failure, so I'm curious. Is the failure related to
power-on hours, or number of on-off cycles?
--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
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Re: Suffering from RIFA anxiety!
I have several 80's-90's HP instruments on the bench, have never seen a Rifa failure, so I'm curious. Is the failure related to power-on hours, or number of on-off cycles?
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Re: HP5340A intermittent or thermal problem
Hi, I had a similar problem with my hp5340A counter, the high frequency input did not respond at all. The loop(s) did not lock. It was very difficult to make any serious conclusions. What I then did was to enter an external DC voltage via a 10k resistor into either input pin of the various opamps. The purpose was to make the opamp output swing positive or negative, this would be a check if the opamp was still alive. And bingo, one was stuck in one direction. It was a loop integrator, I changed the opamp and the instrument was back in operation.
G?ran
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Re: Suffering from RIFA anxiety!
Right !
Le 11/09/2022 03:35, Jared Cabot via
groups.io a ¨¦crit?:
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Show quoted text
The best time to replace Rifa capacitors is
immediately. ;)
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Re: Z3801A GPS (Was Z3804A)
And this was my solution in 2004:
Dan in Chandler, AZ
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Re: Suffering from RIFA anxiety!
On 11/09/2022 02:35, Jared Cabot via groups.io wrote: The best time to replace Rifa capacitors is immediately. ;) Or sooner if possible! The last ones I had fail were over three years ago and even now in the still, dark watches of the night, as the north wind howls round the creaking ancient timbers of the barn....that smell lingers....
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I managed to squeeze in a linear home brew supply behind the front panel on one of my Z3801s. I then replaced the top cover with copper screen mesh, to help with the additional heat from the PS. My antenna is on the peak of my Colonial house and I used special low loss coax (approx. 50 feet) and no amp. I also replaced the 48 volt connector on the rear with a regular 3 contact AC connector. So, just plug and play, and it plays well. ¨C Mike ? Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 ?
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From: [email protected] < [email protected]> On Behalf Of si_emi_01 Sent: Sunday, September 11, 2022 1:05 AM To: [email protected]Subject: Re: [HP-Agilent-Keysight-equipment] HP Z3804A ? Hi, ? If 28dBi isn¡¯t enough gain, you can increase it with an in-line preamplifier. The Z3801A Manual (page 2-4), even mentions it for long cable runs ¨C including cascading them for long runs and lossy cables. ? Vendors used to make amplifiers for CATV and Satellite TV. They are still available dirt cheap - $7.95 USD on ePay. They have a frequency range of 950MHz to 2150MHz. ? They have F Connectors - they¡¯re for TV Stuff, right? I just a Male and Female BNC to F Connector adapters. You just patch it in. I have heard of people cascading them too, dumb ¨C where is that signal now in all of this noise? Grin ¨C contradiction, I guess. ? They say it needs 12V minimum to power it. The Z3801A supplied 5V works fine, you just get less gain of course. It doesn¡¯t seem to over current the Z3801A supply either. I¡¯m sure the 75 Ohm to 50 Ohm mismatch VSWR is relatively poor 1.5:1 or more, it does work. ? I don¡¯t know if you would have success with 3.3V though. It may not bias-up with whatever device they are using with their design. Mine is an RCA brand ¨C got it at Walmart a long time ago. ? I have the Amplifier in line (about 10 feet of cable from the Antenna), plus another 10 foot cable connected to my Z3801A RF Port and it does work. I get around 9dB gain at 1575MHz. It does have kind of a crappy Noise Figure specification, but you still get enough gain to make it worthwhile. My antenna is in the house on the second level and I generally see 4 of 6 satellites all of the time. It goes into ¡°Holdover Mode¡± very occasionally. ? Since the same GPS Engine is probably used for the Z3801A and Z3804A, it should have 5V from the Z3804A. It passes the 5V through to the GPS Antenna for its operation. ? I added the in-line Amplifier in early 2004 and it has been operating without incident since then ¨C 19 years. ? I use GPS-Con for the Console on my main computer. I like it. ? ? HP Z3801A Modifications ---------------------------------- I bought my Z3801A in March 2003. I built a -50V Linear Power Supply for it, put that on a UPS. I have seen it pull over 1A for a short period of time when the OXCO is cold until the Outside Blanket is up to temperature. It draws much less than that afterwards. ? I modified it for the RS232 Interface instead of the RS-422 Interface and connected that to a cable with a USB to RS232 Dongle ¨C the Software Driver doesn¡¯t work with the Dongle Chip on it now. Using direct cabling for now. ? I also made a translator followed by a paralleled 74F38 Driver and Pullup plus series Cable termination for the 1PPS Output. That connector is on the Front Panel with a similar translated and buffered 10MHz TTL Signal Connector as well. ? I also added a 7404 to drive an LED for a Front Panel heartbeat indicator. ? ? Does anyone know of a Dongle that works with the Windows 10 Driver? It used to work but now comes up with a message that the Driver and Hardware Dongle are incompatible. ? ? Ross ?
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Hi, ? If 28dBi isn¡¯t enough gain, you can increase it with an in-line preamplifier. The Z3801A Manual (page 2-4), even mentions it for long cable runs ¨C including cascading them for long runs and lossy cables. ? Vendors used to make amplifiers for CATV and Satellite TV. They are still available dirt cheap - $7.95 USD on ePay. They have a frequency range of 950MHz to 2150MHz. ? They have F Connectors - they¡¯re for TV Stuff, right? I just a Male and Female BNC to F Connector adapters. You just patch it in. I have heard of people cascading them too, dumb ¨C where is that signal now in all of this noise? Grin ¨C contradiction, I guess. ? They say it needs 12V minimum to power it. The Z3801A supplied 5V works fine, you just get less gain of course. It doesn¡¯t seem to over current the Z3801A supply either. I¡¯m sure the 75 Ohm to 50 Ohm mismatch VSWR is relatively poor 1.5:1 or more, it does work. ? I don¡¯t know if you would have success with 3.3V though. It may not bias-up with whatever device they are using with their design. Mine is an RCA brand ¨C got it at Walmart a long time ago. ? I have the Amplifier in line (about 10 feet of cable from the Antenna), plus another 10 foot cable connected to my Z3801A RF Port and it does work. I get around 9dB gain at 1575MHz. It does have kind of a crappy Noise Figure specification, but you still get enough gain to make it worthwhile. My antenna is in the house on the second level and I generally see 4 of 6 satellites all of the time. It goes into ¡°Holdover Mode¡± very occasionally. ? Since the same GPS Engine is probably used for the Z3801A and Z3804A, it should have 5V from the Z3804A. It passes the 5V through to the GPS Antenna for its operation. ? I added the in-line Amplifier in early 2004 and it has been operating without incident since then ¨C 19 years. ? I use GPS-Con for the Console on my main computer. I like it. ? ? HP Z3801A Modifications ---------------------------------- I bought my Z3801A in March 2003. I built a -50V Linear Power Supply for it, put that on a UPS. I have seen it pull over 1A for a short period of time when the OXCO is cold until the Outside Blanket is up to temperature. It draws much less than that afterwards. ? I modified it for the RS232 Interface instead of the RS-422 Interface and connected that to a cable with a USB to RS232 Dongle ¨C the Software Driver doesn¡¯t work with the Dongle Chip on it now. Using direct cabling for now. ? I also made a translator followed by a paralleled 74F38 Driver and Pullup plus series Cable termination for the 1PPS Output. That connector is on the Front Panel with a similar translated and buffered 10MHz TTL Signal Connector as well. ? I also added a 7404 to drive an LED for a Front Panel heartbeat indicator. ? ? Does anyone know of a Dongle that works with the Windows 10 Driver? It used to work but now comes up with a message that the Driver and Hardware Dongle are incompatible. ? ? Ross ? ? ?
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From: [email protected] < [email protected]> On Behalf Of paulswed Sent: Saturday, September 10, 2022 7:57 PM To: [email protected]Subject: Re: [HP-Agilent-Keysight-equipment] HP Z3804A ? Power up the unit and check the antenna connector to ground with a dvm. Believe you will see. 5 V. Good to check. However if the z380X is newer maybe 3.3V. That antenna should work as long as the cables not to long and the antenna has a good view of the sky. 28 db gains not all that much. But may be good enough for your check. Best of luck you are making progress. I see Dave answered is a Motorola Oncore receiver.
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Re: Suffering from RIFA anxiety!
On 9/10/22 22:12, Matt Huszagh wrote: Those are the problematic ones. They will fail. The cracking that
you see is the beginning of the failure. We've replaced dozens of them
at LSSM, some having exploded while others had gotten close. They
aren't "horror stories", it's a well-known and understood failure mode. What's your policy on Schaffner filters? As I understand it, these often
contain the same problematic metallized paper in epoxy safety caps and
exhibit the same failure mechanism as standalone RIFAs. But they're a
bit less convenient to replace.
If you replace them, do you choose a mechanically-compatible modern
Schaffner? I guess the alternative would be to open the filter and
replace just the caps, but that doesn't seem so easy.
Actually I don't think we've run into any of those at LSSM, and I've not had any fail in my own test equipment either. I guess I've gotten lucky there. Though most people say that the big problems with Schaffners show up when an instrument that had a previous life in a 115V country is moved to a 230V country. We should probably adopt a replace-on-sight policy for those at LSSM, but most of the hardware on exhibit there mostly predates the existence of IEC connectors, and thus the all-in-one line entry modules. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
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If it has been powered down for long enough for the almanac data to become invalid (~6 months), it can take a lot longer than that.
-Dave
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On 9/10/22 23:42, Dave Seiter wrote: Shouldn't take a day; I fire mine up every once in a while, and it usually locks in less than 10 minutes (and that's with an indoor antenna).
-Dave
On Saturday, September 10, 2022 at 08:32:00 AM PDT, paulswed <paulswedb@...> wrote:
Hello to the group well I'll be darned. Never seen one either. But it surely appears to be a Z380X inside of a distribution amplifier.
Very very nice. Thats a great find.
If you power it up, it will need an older 5V GPS antenna. Nothing fancy. Given thats its been off most likely a long time it could take a day to lock. But that depends on what the actual GPS receiver is. I cannot tell. There is a bit of label?over the chip that might give a clue.
But thanks for the hi res pix that was very helpful.
Regards
Paul
WB8TSL
--
Dave McGuire, AK4HZ
New Kensington, PA
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Shouldn't take a day; I fire mine up every once in a while, and it usually locks in less than 10 minutes (and that's with an indoor antenna).
-Dave
On Saturday, September 10, 2022 at 08:32:00 AM PDT, paulswed <paulswedb@...> wrote:
Hello to the group well I'll be darned. Never seen one either. But it surely appears to be a Z380X inside of a distribution amplifier. Very very nice. Thats a great find.? If you power it up, it will need an older 5V GPS antenna. Nothing fancy. Given thats its been off most likely a long time it could take a day to lock. But that depends on what the actual GPS receiver is. I cannot tell. There is a bit of label?over the chip that might give a clue. But thanks for the hi res pix that was very helpful. Regards Paul WB8TSL
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On Sat, Sep 10, 2022 at 06:57 PM, paulswed wrote:
Ozan
Power up the unit and check the antenna connector to ground with a dvm. Believe you will see. 5 V. Good to check. However if the z380X is newer maybe 3.3V.
That antenna should work as long as the cables not to long and the antenna has a good view of the sky. 28 db gains not all that much. But may be good enough for your check.
Best of luck you are making progress. I see Dave answered is a Motorola Oncore receiver.
Regards
Paul
---- Thank you Paul. I will send updates as I find more about ?this box. Ozan
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On Sat, Sep 10, 2022 at 03:24 PM, Dave McGuire wrote:
On 9/10/22 18:15, Ozan wrote:
Looking at it again I think you are right, this unit seems to be a
prototype based on mix of two existing products. Board on the top is
bolted only at 3 places to two bars with large portions unsupported, not
production-HP like. I am not next to the unit but I will check the
serial number and report. It is possible the box and bottom board is an
existing distribution amplifier, top board is an existing GPS receiver,
?likely?59551A. ?ROMs on the top board have stickers that say
59551-8000x. I will check if any of HP distribution amplifiers match to
bottom board.
I see GPS antennas that advertise 3V-5V operation with 28dB gain. Is
there anything particular I should look for?
I attached the picture of what I think is the GPS board.
That's a Motorola Oncore GPS receiver module.
-Dave
--- Thank you Dave. A search returns quite a bit of information about Oncore GPS modules.? Ozan
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Randy.AB9GO
Dave McGuire
Precaud
G?ran Krusell