Re: HP YIG replacement 3-7GHz
Hello Lothar the device is AT41000 or AT42000 of course obsolete. I am sure if we could find a reliable source it maybe would get CT1DMK to use his bonder for repairs again. I know he is out of parts but has repaired them in the past.
I love impossible challenges. People always told me the Rythm tower from HP8563E would be impossible to adjust. But none of the less I can do that on daily basis if needed. It was a long road but now possible. In this case a Scalar netwoek analyzers 26.5Ghz
comes in handy as the detektor is broadband so i look at the downconverted IF signal. I use that for adjustments at all frequencies
73 Peter OZ1LPR
The first challenge is to figure out the transistor they used , HP had their own foundry and not all parts they made were sold as products on the open market.
Given the frequency range of the yig it was likely to be a HBT rather than a GaAs Fet but HP semiconductor became Avago and then broadcom and to my knowledge they don¡¯t sell die level parts!
The next challenge then is to remove the old transistor and mount a new one, usually devices are mounted using eutectic solder preforms , the stage is heated until the solder melts and the part is then ¡°scrubbed ¡° in as gold from the back metalization
diffuses into the solder the melting point increases and the solder solidifies , in order to remove the part you would have to heat up the solder past the new melting point without imposing thermal stress on the other parts used or dislocating them !
To mount a new part you need a die attach as well as preforms, you could of course use conductive epoxy but the heat transfer generally is not as good as with eutectic die attach so you might run into issues with reliability!
As far as wirebonders concerns there are plenty on ebay , expect to pay between $5000 and $16000 for a refurbished one , for this type of work you need a wedge/wire bonder , if you plan on rebuilding modules plan on getting a deep access bonder or a convertible
machine that can be used for different processes .
The biggest challenge with bonding is to figure out the right settings though, usually in a production environment the supplier of the semiconductor devices used provides bond samples which in essence are parts that are not working ok those samples are
then bonded in a dummy circuit and a pull tester is used to check the strength of the bond?
Also make sure you have someone with a steady hand and young eyes to threat the bonder ? and also invest in a vibration isolation table or platform to set your bonder on?
toggle quoted message
Show quoted text
On Mar 22, 2022, at 02:28, Peter Hansen via groups.io <oz1lpr@...> wrote:
?
I have succeded to integrate a YO84 YIG faily simple and you can use +/-15 for 30V for heater it is ok and shunting the Sense resistors in the Maincoil driver means it can span the 3-7Ghz. I have made changes to the Loop so it is yield low Phase noise. Output
from the YIG it self is good also. Mechanical implementation is done by using the original mechanic shell and make a hole for the YIG. It can be jammed in there when I mount the YIG in the unit. A PCB "still prototype" is mounted with a 10pin pinheader so
the orignal cable can be used. BUT BUT now the challenge. The original YIG does not get hot due to the sensitve coils meaning less drift. If the Loop is opened by placing the jumper in the TEST position I observe a drift of the YIG of around 5Mhz from cold
to warm. The Avantek YIG drift around 30-40Mhz. The Loop is build to compensate for 10Mhz drift. This means you can either have a unlock condition ERR301 during warm up or you will get it during use.
Playing around in the Loop is not a things for the average guy to do. The Frequency Lock? circuit is quite hard to work with. Changes to the loop will also challenge your phasenoise performance. I am sure this is why HP deviated from the standard sensitivity
on the maincoil to keep drift down. The avantek YIG gets hot the HP ones do not.
More fruitfull would be to find a replacement for the Bonded Transistor and get someone with a Wirebonder to service them.
I do currently not have a wirebonder but as I am repairing alot of advanced HP equipment I am considering it. But where to source components for tryouts.
best regards Peter OZ1LPR
Hi Peter, Et al,
Sorry for the delayed response to all the positive comments. I have been away camping, soaking up what is left of the good weather in autumn, trying my new HF radio set up.
No doubt, there will be many challenges ahead, but I am determined to find a solution. I am waiting on a mail from Micro Lambda to see if they have ever made a replacement, the chap is going to ask the question for me, they have been so helpful to date. There
are other Micro Lambda models to suit Tek and R&S, so they have made replacement models for branded SA and Sign Gens. No harm asking.?
Peter, I think the original HP data sheet is right, this does represent a challenge at? or around 40MHz/mA, the hardware and software is tightly integrated, thus a YIG with similar spec or the development of an interface driver is needed. I haven't thought
that far ahead yet.
Like yourself, and I am sure others on the forum have purchased a YIG in the past to adapt, I purchased a Avantek Y084-1215 about 10 years ago, I recently tried to adapt via a crude interface driver, but this did not work out to well. Although the Avantek YIG
works extremely well for it's vintage, it's main coil spec is way out at ~22.4 MHZ/mA. In addition, getting the juice to run the heater from an internal supply is a challenge.
I am prepared to lay out the cash up to a point to develop a solution.
I hope I do not have to eat my words in time.
Stay tuned.
Regards
Gerald
VK3GM
?
|
Re: HP8444A 1.55GHz oscillator
Hi, I bought several years ago an 8444A opt59, this device was new, bought from HP directly. The service manual sold with this unit was the 1817A, with a "manual change" addition for the 2103A, 2121A, 2126A and 2325A. My 8444A is a 2325A. ? Maybe this information can help you. ? ? -Yves ? ? Hi! I've been looking at an HP8444A tracking generator originally for 140 series but used with an 858B. It seems to be a late serial unit 2126A.? Oscillator A7 is similar (but not identical - the coupling to the cavity is adjustable in this one) to the one in the 1323A manual and the 1817A prefix manual. I don't have a later manual - neither does Artek. Having replaced the transistor it is now oscillating at a reasonable (but not quite correct frequency).? When I came to tune I found two adjusters one coupling between transistor and cavity and the other a more normal capacitative tuning adjuster.? The earlier manuals only have one - has anyone seen an adjustment procedure for the two adjuster version??? My frequency reference is not without suspicion?(HP5245L with 0.3-3GHz plugin) which seems the only counter I have that goes over 1GHz. They are great things but it's rare to have no other option but to use it, but now with a new 61 tooth gear (thanks HP for choosing a large prime) it works!
|
Re: HP YIG replacement 3-7GHz
The first challenge is to figure out the transistor they used , HP had their own foundry and not all parts they made were sold as products on the open market.
Given the frequency range of the yig it was likely to be a HBT rather than a GaAs Fet but HP semiconductor became Avago and then broadcom and to my knowledge they don¡¯t sell die level parts!
The next challenge then is to remove the old transistor and mount a new one, usually devices are mounted using eutectic solder preforms , the stage is heated until the solder melts and the part is then ¡°scrubbed ¡° in as gold from the back metalization
diffuses into the solder the melting point increases and the solder solidifies , in order to remove the part you would have to heat up the solder past the new melting point without imposing thermal stress on the other parts used or dislocating them !
To mount a new part you need a die attach as well as preforms, you could of course use conductive epoxy but the heat transfer generally is not as good as with eutectic die attach so you might run into issues with reliability!
As far as wirebonders concerns there are plenty on ebay , expect to pay between $5000 and $16000 for a refurbished one , for this type of work you need a wedge/wire bonder , if you plan on rebuilding modules plan on getting a deep access bonder or a convertible
machine that can be used for different processes .
The biggest challenge with bonding is to figure out the right settings though, usually in a production environment the supplier of the semiconductor devices used provides bond samples which in essence are parts that are not working ok those samples are
then bonded in a dummy circuit and a pull tester is used to check the strength of the bond?
Also make sure you have someone with a steady hand and young eyes to threat the bonder ? and also invest in a vibration isolation table or platform to set your bonder on?
toggle quoted message
Show quoted text
On Mar 22, 2022, at 02:28, Peter Hansen via groups.io <oz1lpr@...> wrote:
?
I have succeded to integrate a YO84 YIG faily simple and you can use +/-15 for 30V for heater it is ok and shunting the Sense resistors in the Maincoil driver means it can span the 3-7Ghz. I have made changes to the Loop so it is yield low Phase noise. Output
from the YIG it self is good also. Mechanical implementation is done by using the original mechanic shell and make a hole for the YIG. It can be jammed in there when I mount the YIG in the unit. A PCB "still prototype" is mounted with a 10pin pinheader so
the orignal cable can be used. BUT BUT now the challenge. The original YIG does not get hot due to the sensitve coils meaning less drift. If the Loop is opened by placing the jumper in the TEST position I observe a drift of the YIG of around 5Mhz from cold
to warm. The Avantek YIG drift around 30-40Mhz. The Loop is build to compensate for 10Mhz drift. This means you can either have a unlock condition ERR301 during warm up or you will get it during use.
Playing around in the Loop is not a things for the average guy to do. The Frequency Lock? circuit is quite hard to work with. Changes to the loop will also challenge your phasenoise performance. I am sure this is why HP deviated from the standard sensitivity
on the maincoil to keep drift down. The avantek YIG gets hot the HP ones do not.
More fruitfull would be to find a replacement for the Bonded Transistor and get someone with a Wirebonder to service them.
I do currently not have a wirebonder but as I am repairing alot of advanced HP equipment I am considering it. But where to source components for tryouts.
best regards Peter OZ1LPR
Hi Peter, Et al,
Sorry for the delayed response to all the positive comments. I have been away camping, soaking up what is left of the good weather in autumn, trying my new HF radio set up.
No doubt, there will be many challenges ahead, but I am determined to find a solution. I am waiting on a mail from Micro Lambda to see if they have ever made a replacement, the chap is going to ask the question for me, they have been so helpful to date. There
are other Micro Lambda models to suit Tek and R&S, so they have made replacement models for branded SA and Sign Gens. No harm asking.?
Peter, I think the original HP data sheet is right, this does represent a challenge at? or around 40MHz/mA, the hardware and software is tightly integrated, thus a YIG with similar spec or the development of an interface driver is needed. I haven't thought
that far ahead yet.
Like yourself, and I am sure others on the forum have purchased a YIG in the past to adapt, I purchased a Avantek Y084-1215 about 10 years ago, I recently tried to adapt via a crude interface driver, but this did not work out to well. Although the Avantek YIG
works extremely well for it's vintage, it's main coil spec is way out at ~22.4 MHZ/mA. In addition, getting the juice to run the heater from an internal supply is a challenge.
I am prepared to lay out the cash up to a point to develop a solution.
I hope I do not have to eat my words in time.
Stay tuned.
Regards
Gerald
VK3GM
?
|
Re: Agilent 3458A Troubleshooting
... this is interesting re battery age, which battery dies first etc:
Alan
|
Re: Agilent 3458A Troubleshooting
p.s. clip of start-up sequence here:
After lighting up all the display segments it says 'TESTING RAM' and then 'TESTING HARDWARE'. About 4 seconds to first reading.
Alan
|
Re: Agilent 3458A Troubleshooting
Hi George,
>>>?6.????The ROMs are socketed. I will try pulling these out and reinserting them. Unfortunately I do not have a spare set.
These are easy enough to make from new. Just buy new chips, download the firmware (e.g. from xDevs), and program with a cheap TL866 programmer or similar. (Or just use the programmer to compare your current ROM contents with a known good download.)
>>>?7.????The Dallas NVRAMs should not affect the BIOS. They are soldered in. I will replace them once I get the meter going.
I'm pretty sure the firmware accesses these on start-up - others may comment. If it sees zeros or nonsense in the calram on boot, it may just stop with a dumbfounded grin :) For testing, you can always download any old machine's calram contents and program up a spare Dallas chip. But do see if you can read the old calram contents though - that may save you a $K or so. If it was me, I wouldn't progress further much without ensuring I had some valid ROM & RAM. Catch 22, but once you can get it to boot you can download the calram contents over gpib.
Yeah, Dave is in Sydney. Also last time I looked (several years ago) - you could still buy some parts from Keysight. I'm not sure if that's still the case.
Alan
|
Re: Agilent 3458A Troubleshooting
Hi Alan, ? Thank you for your post and the encouraging comment about getting the 3458A going. I have my fingers crossed. ? In answer to the points you have raised: ? 1.??? xDevs and eevBlog ¨C I am aware of these and have watched some of the Youtube videos. I thought I would start with groups.io and move on to these later. 2.??? Check power and for toasted components ¨C done, all OK 3.??? Double check for correctly plugged cable connectors etc. ¨C done, all OK 4.??? Boot sequence ¨C I think it is starting the boot sequence properly. The single BEEP at power ON I presume means it has past the first step in POST. I found a very informative site about POST for PCs here: ?
? ??????????? I am guessing the 3458A functions in a similar manner when booting up. ? 5.??? Display voltages ¨C checked OK 6.??? The ROMs are socketed. I will try pulling these out and reinserting them. Unfortunately I do not have a spare set. 7.??? The Dallas NVRAMs should not affect the BIOS. They are soldered in. I will replace them once I get the meter going. 8.??? Electrolytics ¨C I will replace them once I get the meter going. 9.??? Provenance ¨C I found a sticker with Intel written on it. 10. Boards ¨C I will do this if I get desperate. I would rather track down the fault logically if I can. Unfortunately I don¡¯t have any spare boards for swapping. 11. Manuals ¨C I have a lot of info, including the CLIP, but there is no mention of what the flashing single square on the display means. 12. Dave eevBlog ¨C I must get in contact with him. I have seen his Youtube videos. I know he is Australian. I hope he is in Sydney! ? Thank you for providing the checklist ¨C most helpful. ? Cheers, George Georgevits (BE Hons, PhD) Consulting Engineer ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of alan.ambrose@...
Sent: Tuesday, 22 March 2022 1:41 AM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Agilent 3458A Troubleshooting ? Hi George,
Well the good news is that it is something basic rather than something (as yet) complicated.... :)
Another vote here for xDevs site & EEVblog?forum threads. I assume you've done a complete check for power & toasted components. Double check that everything is plugged in where it should be (say, by comparison with say xDevs images) - and that all the cables and sockets seem good. Particularly those to the digital board and display (and check the display voltage too) - it sounds like it's not even starting its boot sequence properly.
If not socketed already, I agree with your intuition, and would desolder, read and then socket the Dallas rams and ROMs. Compare ROMs against known good and also see if you can get any data out of the Dallas rams - I would think you have more than a 50/50 chance. You may want to change the electrolytics while you're there - a list is on my site:?
You don't say much about the provenance - maybe there isn't any, but maybe you can get a few clues? Re: 'but someone has maintained over the years' - hmmm, I think I might take all the boards out and give both sides a good look under a magnifier to see if you can see whether any detail work has been done already. Great care with fingerprint contamination of the analogue board of course. A swap with a known good digital board would be a helpful and quick diagnosis aid if you can borrow one. All the manuals, including schematics, are out there as pdfs, of course.
Ah, you're in Sydney! - I think there's a good chance EEVblog Dave could help a lot in person :) From (hazy) memory I think he has a 3458a or two to compare with / test against.
Alan
|
HP8444A 1.55GHz oscillator
Hi!
I've been looking at an HP8444A tracking generator originally for 140 series but used with an 858B. It seems to be a late serial unit 2126A.? Oscillator A7 is similar (but not identical - the coupling to the cavity is adjustable in this one) to the one in the 1323A manual and the 1817A prefix manual. I don't have a later manual - neither does Artek.
Having replaced the transistor it is now oscillating at a reasonable (but not quite correct frequency).? When I came to tune I found two adjusters one coupling between transistor and cavity and the other a more normal capacitative tuning adjuster.? The earlier manuals only have one - has anyone seen an adjustment procedure for the two adjuster version???
My frequency reference is not without suspicion?(HP5245L with 0.3-3GHz plugin) which seems the only counter I have that goes over 1GHz. They are great things but it's rare to have no other option but to use it, but now with a new 61 tooth gear (thanks HP for choosing a large prime) it works!
Alan
|
Re: HP YIG replacement 3-7GHz
I have succeded to integrate a YO84 YIG faily simple and you can use +/-15 for 30V for heater it is ok and shunting the Sense resistors in the Maincoil driver means it can span the 3-7Ghz. I have made changes to the Loop so it is yield low Phase noise. Output
from the YIG it self is good also. Mechanical implementation is done by using the original mechanic shell and make a hole for the YIG. It can be jammed in there when I mount the YIG in the unit. A PCB "still prototype" is mounted with a 10pin pinheader so
the orignal cable can be used. BUT BUT now the challenge. The original YIG does not get hot due to the sensitve coils meaning less drift. If the Loop is opened by placing the jumper in the TEST position I observe a drift of the YIG of around 5Mhz from cold
to warm. The Avantek YIG drift around 30-40Mhz. The Loop is build to compensate for 10Mhz drift. This means you can either have a unlock condition ERR301 during warm up or you will get it during use.
Playing around in the Loop is not a things for the average guy to do. The Frequency Lock? circuit is quite hard to work with. Changes to the loop will also challenge your phasenoise performance. I am sure this is why HP deviated from the standard sensitivity
on the maincoil to keep drift down. The avantek YIG gets hot the HP ones do not.
More fruitfull would be to find a replacement for the Bonded Transistor and get someone with a Wirebonder to service them.
I do currently not have a wirebonder but as I am repairing alot of advanced HP equipment I am considering it. But where to source components for tryouts.
best regards Peter OZ1LPR
Hi Peter, Et al,
Sorry for the delayed response to all the positive comments. I have been away camping, soaking up what is left of the good weather in autumn, trying my new HF radio set up.
No doubt, there will be many challenges ahead, but I am determined to find a solution. I am waiting on a mail from Micro Lambda to see if they have ever made a replacement, the chap is going to ask the question for me, they have been so helpful to date. There
are other Micro Lambda models to suit Tek and R&S, so they have made replacement models for branded SA and Sign Gens. No harm asking.?
Peter, I think the original HP data sheet is right, this does represent a challenge at? or around 40MHz/mA, the hardware and software is tightly integrated, thus a YIG with similar spec or the development of an interface driver is needed. I haven't thought
that far ahead yet.
Like yourself, and I am sure others on the forum have purchased a YIG in the past to adapt, I purchased a Avantek Y084-1215 about 10 years ago, I recently tried to adapt via a crude interface driver, but this did not work out to well. Although the Avantek YIG
works extremely well for it's vintage, it's main coil spec is way out at ~22.4 MHZ/mA. In addition, getting the juice to run the heater from an internal supply is a challenge.
I am prepared to lay out the cash up to a point to develop a solution.
I hope I do not have to eat my words in time.
Stay tuned.
Regards
Gerald
VK3GM
?
|
Re: HP YIG replacement 3-7GHz
Gerald,
If you approach Micro Lambda, I would do so with an extensive list of products that use this particular design which was internally called ¡°EYO¡± (economy YIG oscillator). If you can impress on them that there could be a reasonably large market for such a family of oscillators, they might consider making them. So, make a list if you can. Keep in mind that there were many variants (8753 series VNAs, various portable spectrum analyzers, 70000 systems, maybe some signal generators, etc.).
Things to keep in mind:
- Tuning sensitivity (main coil and FM)
- Power supplies. The basic EYO used +15 and +5V and no negative supply.
- The EYO has no heater, so the replacement shouldn¡¯t either.
- Size and mounting hole locations.
- Output power
- The frequency range must extend down to 3 GHz in order for fit some products.
I don¡¯t think there would be many buyers for such an oscillator if it sells for more than $500, but I may be wrong.
Vladan
|
No I left UT about 5 years ago ?since the only point of this was to prove a somewhat snotty know it all PhD student wrong I didn¡¯t see no need to take the files with me
?
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From: [email protected] < [email protected]>
On Behalf Of n8zmTWH via groups.io
Sent: Monday, March 21, 2022 11:33 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Protecting Equipment
?
Still have them to share?
?
?
?
Yes , I did a baseline first without the limiter , then the limiter was inserted and another sweep was done , the results were overlayed
?
?
At those levels did you do a power sweep both with and without the limiter to observe the non-linear distortion products of the sig gen and SA?
?
?
?
1GHz only?
?
?
On Mar 21, 2022, at 19:52, n8zmTWH via groups.io <n8zmTWH@...> wrote:
?
What Frequencies?
?
?
?
?
Agilent E8257D 20GHz Signal generator ?, N9030A 50GHz spectrum analyzer , power sweep in 0.5Db steps from 0 to 30dBm CW
?
?
³¢´Ç³Ù³ó²¹°ù¡
?
What test gear did you use for the power sweep and what were the test points? I have a couple here I¡¯d like to compare.
?
?
?
Years ago I had this discussion with a PhD student ,? his argument was that the limiter doesn¡¯t matter unless it is triggered so I set up a experiment doing a power sweep of the limiter and capturing the output spectrum for each point ,?
he was quite surprised
?
?
Lothar,
?
Correct. The same thing happens with Zeners below 6.2V and TVS Diodes (way too much Capacitance for RF Applications).
?
Look at the Breakover point of the RF Limiter (or TVS), it is a curve. Its Impedance changes below the breakover voltage as current flows through it and approaches the knee. If it is not specified, it can be obtained via a Curve Tracer
or manually generated I-V Curves that you can produce with a simple Power Supply UUT and Resistance Standard or Resistance Decade.
?
Many Signal Integrity issues develop when they are not used properly and the curve is well understood.
?
Ross
?
?
What many people seem to forget is the fact that the non linear behavior of a limiter kicks in way before the limiter is actually ¡°triggered¡± ?although the distortions are not as bad
?
?
Tom,
?
That is also why MIL-STD-461 CE102 requires a 20dB Pad on the signal path from the LISN to the Receiver. They do not recommend a Limiter due to non-linearities that Lothar points out.
?
Limiters can really hurt the Noise Figure of a receiver input at well.
?
Ross
?
?
Limiters are very commonly recommended for Conducted Immunity testing in EMC labs where the Spec An input comes from the Line Impedance Stabilization Network (LISN) because the
turn on/off transients can be quite high. The levels expected to be measured typically should be much less than the distortion level of the limiter. The recommended limiter in this case actually has an intentional 10 dB insertion loss.
?
?
?
A few words about limiters ,
Generally limiters are used in systems to protect receivers usually in RADAR or EW applications ,? in test systems the use of limiters s usually frowned upon ( with very few exceptions)? and for good reason !
First of there is a cost penalty that is not insignificant , the cost for a connectorized limiter usually starts at about $600 and can go up into the $2K range .
Limiters also degrade VSWR and add additional system loss .
But the by far biggest problem is that limiters are non linear devices and as such excellent harmonics generators , harmonics will start to occur before the limiter hits the hard threshold and worsens as the power increases so if you put
one in front a spectrum analyzer you have to be cautious not to end up with tst results that are worse than they actually are
?
?
Mini-Circuits sells limiters as well as DC blocks, but they only go up to 8 GHz.? Not sure about the price, but they are most likely competitive.? Assuming you actually need
one.
------ Original Message ------
Sent: 3/20/2022 6:52:14 AM
Subject: Re: [HP-Agilent-Keysight-equipment] Protecting Equipment
It's worth adding that a DC block only provides some measure of safety. The ramp up voltage of a DC signal is an AC signal and can pass right through your series cap. If you
look at DC blocking filter designs like the HP 3048A option K23, there's a limiter after the series cap. It seems like the "right" devices for this sort of thing are RF power limiters. Unfortunately, the cost of many of these devices new from reputable manufacturers
probably matches or exceeds what many people paid for their second-hand spectrum analyzer. Maybe there are good second-hand market options, but I haven't looked into to it. If you want something to reliably protect a low frequency SA, that shouldn't be too
hard to design and build. But, if you want to get the full 22 GHz range out of your 8566, I expect that wouldn't be so easy.
|
Re: HP YIG replacement 3-7GHz
Some of the agilent and rohde YTO were made by microsource , unfortunately microsource was bought out by gigatronics and I don¡¯t know if they still sell the YIGs as separate products ,? I expect for micro lambda to be tight lipped if it
comes to ¡°replacement¡± yigs as I know they make yigs for rohde and I assume also some for agilent and I am sure neither company would be happy if micro lambda were to undercut their spare part sales
?
As far as Avantek concerns you are talking about a entirely different generation of YIGs ,20MHz/Ma is actually common for tuning sensitivity of the main coil however agilent as well as WJ departed from this value !
?
Here is some info on the drivers
?
?
toggle quoted message
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From: [email protected] < [email protected]>
On Behalf Of Gerald via groups.io
Sent: Monday, March 21, 2022 10:34 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP YIG replacement 3-7GHz
?
Hi Peter, Et al,
Sorry for the delayed response to all the positive comments. I have been away camping, soaking up what is left of the good weather in autumn, trying my new HF radio set up.
No doubt, there will be many challenges ahead, but I am determined to find a solution. I am waiting on a mail from Micro Lambda to see if they have ever made a replacement, the chap is going to ask the question for me, they have been so helpful to date. There
are other Micro Lambda models to suit Tek and R&S, so they have made replacement models for branded SA and Sign Gens. No harm asking.?
Peter, I think the original HP data sheet is right, this does represent a challenge at? or around 40MHz/mA, the hardware and software is tightly integrated, thus a YIG with similar spec or the development of an interface driver is needed. I haven't thought
that far ahead yet.
Like yourself, and I am sure others on the forum have purchased a YIG in the past to adapt, I purchased a Avantek Y084-1215 about 10 years ago, I recently tried to adapt via a crude interface driver, but this did not work out to well. Although the Avantek YIG
works extremely well for it's vintage, it's main coil spec is way out at ~22.4 MHZ/mA. In addition, getting the juice to run the heater from an internal supply is a challenge.
I am prepared to lay out the cash up to a point to develop a solution.
I hope I do not have to eat my words in time.
Stay tuned.
Regards
Gerald
VK3GM
?
|
Still have them to share? ? ?
toggle quoted message
Show quoted text
From: [email protected] <[email protected]> On Behalf Of Lothar baier
Sent: Tuesday, March 22, 2022 12:23 AM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Protecting Equipment? Yes , I did a baseline first without the limiter , then the limiter was inserted and another sweep was done , the results were overlayed ? ? At those levels did you do a power sweep both with and without the limiter to observe the non-linear distortion products of the sig gen and SA? ? ? ? 1GHz only? ? ? On Mar 21, 2022, at 19:52, n8zmTWH via groups.io <n8zmTWH@...> wrote:
? What Frequencies? ? ? ? ? Agilent E8257D 20GHz Signal generator ?, N9030A 50GHz spectrum analyzer , power sweep in 0.5Db steps from 0 to 30dBm CW ? ? ³¢´Ç³Ù³ó²¹°ù¡ ? What test gear did you use for the power sweep and what were the test points? I have a couple here I¡¯d like to compare. ? ? ? Years ago I had this discussion with a PhD student ,? his argument was that the limiter doesn¡¯t matter unless it is triggered so I set up a experiment doing a power sweep of the limiter and capturing the output spectrum for each point ,? he was quite surprised ? ? Lothar, ? Correct. The same thing happens with Zeners below 6.2V and TVS Diodes (way too much Capacitance for RF Applications). ? Look at the Breakover point of the RF Limiter (or TVS), it is a curve. Its Impedance changes below the breakover voltage as current flows through it and approaches the knee. If it is not specified, it can be obtained via a Curve Tracer or manually generated I-V Curves that you can produce with a simple Power Supply UUT and Resistance Standard or Resistance Decade. ? Many Signal Integrity issues develop when they are not used properly and the curve is well understood. ? Ross ? ? What many people seem to forget is the fact that the non linear behavior of a limiter kicks in way before the limiter is actually ¡°triggered¡± ?although the distortions are not as bad ? ? Tom, ? That is also why MIL-STD-461 CE102 requires a 20dB Pad on the signal path from the LISN to the Receiver. They do not recommend a Limiter due to non-linearities that Lothar points out. ? Limiters can really hurt the Noise Figure of a receiver input at well. ? Ross ? ? Limiters are very commonly recommended for Conducted Immunity testing in EMC labs where the Spec An input comes from the Line Impedance Stabilization Network (LISN) because the turn on/off transients can be quite high. The levels expected to be measured typically should be much less than the distortion level of the limiter. The recommended limiter in this case actually has an intentional 10 dB insertion loss. ? ? ? A few words about limiters , Generally limiters are used in systems to protect receivers usually in RADAR or EW applications ,? in test systems the use of limiters s usually frowned upon ( with very few exceptions)? and for good reason ! First of there is a cost penalty that is not insignificant , the cost for a connectorized limiter usually starts at about $600 and can go up into the $2K range . Limiters also degrade VSWR and add additional system loss . But the by far biggest problem is that limiters are non linear devices and as such excellent harmonics generators , harmonics will start to occur before the limiter hits the hard threshold and worsens as the power increases so if you put one in front a spectrum analyzer you have to be cautious not to end up with tst results that are worse than they actually are ? ? Mini-Circuits sells limiters as well as DC blocks, but they only go up to 8 GHz.? Not sure about the price, but they are most likely competitive.? Assuming you actually need one. ------ Original Message ------ Sent: 3/20/2022 6:52:14 AM Subject: Re: [HP-Agilent-Keysight-equipment] Protecting Equipment It's worth adding that a DC block only provides some measure of safety. The ramp up voltage of a DC signal is an AC signal and can pass right through your series cap. If you look at DC blocking filter designs like the HP 3048A option K23, there's a limiter after the series cap. It seems like the "right" devices for this sort of thing are RF power limiters. Unfortunately, the cost of many of these devices new from reputable manufacturers probably matches or exceeds what many people paid for their second-hand spectrum analyzer. Maybe there are good second-hand market options, but I haven't looked into to it. If you want something to reliably protect a low frequency SA, that shouldn't be too hard to design and build. But, if you want to get the full 22 GHz range out of your 8566, I expect that wouldn't be so easy.
|
Yes , I did a baseline first without the limiter , then the limiter was inserted and another sweep was done , the results were overlayed
?
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Show quoted text
From: [email protected] < [email protected]>
On Behalf Of n8zmTWH via groups.io
Sent: Monday, March 21, 2022 10:44 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Protecting Equipment
?
At those levels did you do a power sweep both with and without the limiter to observe the non-linear distortion products of the sig gen and SA?
?
?
?
1GHz only?
?
On Mar 21, 2022, at 19:52, n8zmTWH via groups.io <n8zmTWH@...> wrote:
?
What Frequencies?
?
?
?
?
Agilent E8257D 20GHz Signal generator ?, N9030A 50GHz spectrum analyzer , power sweep in 0.5Db steps from 0 to 30dBm CW
?
?
³¢´Ç³Ù³ó²¹°ù¡
?
What test gear did you use for the power sweep and what were the test points? I have a couple here I¡¯d like to compare.
?
?
?
Years ago I had this discussion with a PhD student ,? his argument was that the limiter doesn¡¯t matter unless it is triggered so I set up a experiment doing a power sweep of the limiter and capturing the output spectrum for each point ,?
he was quite surprised
?
?
Lothar,
?
Correct. The same thing happens with Zeners below 6.2V and TVS Diodes (way too much Capacitance for RF Applications).
?
Look at the Breakover point of the RF Limiter (or TVS), it is a curve. Its Impedance changes below the breakover voltage as current flows through it and approaches the knee. If it is not specified, it can be obtained via a Curve Tracer
or manually generated I-V Curves that you can produce with a simple Power Supply UUT and Resistance Standard or Resistance Decade.
?
Many Signal Integrity issues develop when they are not used properly and the curve is well understood.
?
Ross
?
?
What many people seem to forget is the fact that the non linear behavior of a limiter kicks in way before the limiter is actually ¡°triggered¡± ?although the distortions are not as bad
?
?
Tom,
?
That is also why MIL-STD-461 CE102 requires a 20dB Pad on the signal path from the LISN to the Receiver. They do not recommend a Limiter due to non-linearities that Lothar points out.
?
Limiters can really hurt the Noise Figure of a receiver input at well.
?
Ross
?
?
Limiters are very commonly recommended for Conducted Immunity testing in EMC labs where the Spec An input comes from the Line Impedance Stabilization Network (LISN) because the
turn on/off transients can be quite high. The levels expected to be measured typically should be much less than the distortion level of the limiter. The recommended limiter in this case actually has an intentional 10 dB insertion loss.
?
?
?
A few words about limiters ,
Generally limiters are used in systems to protect receivers usually in RADAR or EW applications ,? in test systems the use of limiters s usually frowned upon ( with very few exceptions)? and for good reason !
First of there is a cost penalty that is not insignificant , the cost for a connectorized limiter usually starts at about $600 and can go up into the $2K range .
Limiters also degrade VSWR and add additional system loss .
But the by far biggest problem is that limiters are non linear devices and as such excellent harmonics generators , harmonics will start to occur before the limiter hits the hard threshold and worsens as the power increases so if you put
one in front a spectrum analyzer you have to be cautious not to end up with tst results that are worse than they actually are
?
?
Mini-Circuits sells limiters as well as DC blocks, but they only go up to 8 GHz.? Not sure about the price, but they are most likely competitive.? Assuming you actually need
one.
------ Original Message ------
Sent: 3/20/2022 6:52:14 AM
Subject: Re: [HP-Agilent-Keysight-equipment] Protecting Equipment
It's worth adding that a DC block only provides some measure of safety. The ramp up voltage of a DC signal is an AC signal and can pass right through your series cap. If you
look at DC blocking filter designs like the HP 3048A option K23, there's a limiter after the series cap. It seems like the "right" devices for this sort of thing are RF power limiters. Unfortunately, the cost of many of these devices new from reputable manufacturers
probably matches or exceeds what many people paid for their second-hand spectrum analyzer. Maybe there are good second-hand market options, but I haven't looked into to it. If you want something to reliably protect a low frequency SA, that shouldn't be too
hard to design and build. But, if you want to get the full 22 GHz range out of your 8566, I expect that wouldn't be so easy.
|
At those levels did you do a power sweep both with and without the limiter to observe the non-linear distortion products of the sig gen and SA? ? ?
toggle quoted message
Show quoted text
From: [email protected] <[email protected]> On Behalf Of Lothar baier
Sent: Monday, March 21, 2022 9:01 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Protecting Equipment? 1GHz only? ?
On Mar 21, 2022, at 19:52, n8zmTWH via groups.io <n8zmTWH@...> wrote:
? What Frequencies? ? ? ? ? Agilent E8257D 20GHz Signal generator ?, N9030A 50GHz spectrum analyzer , power sweep in 0.5Db steps from 0 to 30dBm CW ? ? ³¢´Ç³Ù³ó²¹°ù¡ ? What test gear did you use for the power sweep and what were the test points? I have a couple here I¡¯d like to compare. ? ? ? Years ago I had this discussion with a PhD student ,? his argument was that the limiter doesn¡¯t matter unless it is triggered so I set up a experiment doing a power sweep of the limiter and capturing the output spectrum for each point ,? he was quite surprised ? ? Lothar, ? Correct. The same thing happens with Zeners below 6.2V and TVS Diodes (way too much Capacitance for RF Applications). ? Look at the Breakover point of the RF Limiter (or TVS), it is a curve. Its Impedance changes below the breakover voltage as current flows through it and approaches the knee. If it is not specified, it can be obtained via a Curve Tracer or manually generated I-V Curves that you can produce with a simple Power Supply UUT and Resistance Standard or Resistance Decade. ? Many Signal Integrity issues develop when they are not used properly and the curve is well understood. ? Ross ? ? What many people seem to forget is the fact that the non linear behavior of a limiter kicks in way before the limiter is actually ¡°triggered¡± ?although the distortions are not as bad ? ? Tom, ? That is also why MIL-STD-461 CE102 requires a 20dB Pad on the signal path from the LISN to the Receiver. They do not recommend a Limiter due to non-linearities that Lothar points out. ? Limiters can really hurt the Noise Figure of a receiver input at well. ? Ross ? ? Limiters are very commonly recommended for Conducted Immunity testing in EMC labs where the Spec An input comes from the Line Impedance Stabilization Network (LISN) because the turn on/off transients can be quite high. The levels expected to be measured typically should be much less than the distortion level of the limiter. The recommended limiter in this case actually has an intentional 10 dB insertion loss. ? ? ? A few words about limiters , Generally limiters are used in systems to protect receivers usually in RADAR or EW applications ,? in test systems the use of limiters s usually frowned upon ( with very few exceptions)? and for good reason ! First of there is a cost penalty that is not insignificant , the cost for a connectorized limiter usually starts at about $600 and can go up into the $2K range . Limiters also degrade VSWR and add additional system loss . But the by far biggest problem is that limiters are non linear devices and as such excellent harmonics generators , harmonics will start to occur before the limiter hits the hard threshold and worsens as the power increases so if you put one in front a spectrum analyzer you have to be cautious not to end up with tst results that are worse than they actually are ? ? Mini-Circuits sells limiters as well as DC blocks, but they only go up to 8 GHz.? Not sure about the price, but they are most likely competitive.? Assuming you actually need one. ------ Original Message ------ Sent: 3/20/2022 6:52:14 AM Subject: Re: [HP-Agilent-Keysight-equipment] Protecting Equipment It's worth adding that a DC block only provides some measure of safety. The ramp up voltage of a DC signal is an AC signal and can pass right through your series cap. If you look at DC blocking filter designs like the HP 3048A option K23, there's a limiter after the series cap. It seems like the "right" devices for this sort of thing are RF power limiters. Unfortunately, the cost of many of these devices new from reputable manufacturers probably matches or exceeds what many people paid for their second-hand spectrum analyzer. Maybe there are good second-hand market options, but I haven't looked into to it. If you want something to reliably protect a low frequency SA, that shouldn't be too hard to design and build. But, if you want to get the full 22 GHz range out of your 8566, I expect that wouldn't be so easy.
|
Re: HP YIG replacement 3-7GHz
Hi Peter, Et al,
Sorry for the delayed response to all the positive comments. I have been away camping, soaking up what is left of the good weather in autumn, trying my new HF radio set up.
No doubt, there will be many challenges ahead, but I am determined to find a solution. I am waiting on a mail from Micro Lambda to see if they have ever made a replacement, the chap is going to ask the question for me, they have been so helpful to date. There are other Micro Lambda models to suit Tek and R&S, so they have made replacement models for branded SA and Sign Gens. No harm asking.?
Peter, I think the original HP data sheet is right, this does represent a challenge at? or around 40MHz/mA, the hardware and software is tightly integrated, thus a YIG with similar spec or the development of an interface driver is needed. I haven't thought that far ahead yet.
Like yourself, and I am sure others on the forum have purchased a YIG in the past to adapt, I purchased a Avantek Y084-1215 about 10 years ago, I recently tried to adapt via a crude interface driver, but this did not work out to well. Although the Avantek YIG works extremely well for it's vintage, it's main coil spec is way out at ~22.4 MHZ/mA. In addition, getting the juice to run the heater from an internal supply is a challenge.
I am prepared to lay out the cash up to a point to develop a solution.
I hope I do not have to eat my words in time.
Stay tuned.
Regards
Gerald
VK3GM
?
|
Re: Question about MMIC amp design for HP 8601a output replacement
I have replaced my hybrid with a design based on the
Dasarodesigns.com replacement.
I have inserted the schematic here - I'm not sure if it will come
through. I used the BFU590Q transistor, and more common resistor
values. I don't use the -6.3 volt supply, I bias the amplifier to
produce +20 dBm all the time. One of the major issues is getting
the heat out. A Spice simulation predicts about 4 watts total
dissipation in this amplifier.
This amplifier probably doesn't meet the spec's of the original,
but I can get about +20 dBm out again, and the 8601a puts out a
reasonably flat sweep to 110 MHz.
My goal was to have a working signal generator again, not
necessarily meeting the original specifications for the 8601a
Gary Appel
On 3/21/2022 12:28 PM, DB via groups.io
wrote:
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Show quoted text
Hi David,
Thanks, I had seen that design on the ARF forum and was originally
considering going that route but then had trouble finding the
BFG35 transistors.? I was thinking that since the newer higher
output MMIC's were readily available it might be a better/simpler
design to go with the MMIC and reduce the parts count quite a
bit.? Hopefully the RF choke and biasing wont complicate this too
much for the lower frequencies.
Thanks
DB
"This design may help with avoiding re-inventing the wheel:
?
?
(No personal experience, just remember the conversation
when it occurred back on the AntiqueRadioForums)
?
David
|
toggle quoted message
Show quoted text
From: [email protected] <[email protected]> On Behalf Of Lothar baier
Sent: Monday, March 21, 2022 9:01 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Protecting Equipment? 1GHz only? ?
On Mar 21, 2022, at 19:52, n8zmTWH via groups.io <n8zmTWH@...> wrote:
? What Frequencies? ? ? ? ? Agilent E8257D 20GHz Signal generator ?, N9030A 50GHz spectrum analyzer , power sweep in 0.5Db steps from 0 to 30dBm CW ? ? ³¢´Ç³Ù³ó²¹°ù¡ ? What test gear did you use for the power sweep and what were the test points? I have a couple here I¡¯d like to compare. ? ? ? Years ago I had this discussion with a PhD student ,? his argument was that the limiter doesn¡¯t matter unless it is triggered so I set up a experiment doing a power sweep of the limiter and capturing the output spectrum for each point ,? he was quite surprised ? ? Lothar, ? Correct. The same thing happens with Zeners below 6.2V and TVS Diodes (way too much Capacitance for RF Applications). ? Look at the Breakover point of the RF Limiter (or TVS), it is a curve. Its Impedance changes below the breakover voltage as current flows through it and approaches the knee. If it is not specified, it can be obtained via a Curve Tracer or manually generated I-V Curves that you can produce with a simple Power Supply UUT and Resistance Standard or Resistance Decade. ? Many Signal Integrity issues develop when they are not used properly and the curve is well understood. ? Ross ? ? What many people seem to forget is the fact that the non linear behavior of a limiter kicks in way before the limiter is actually ¡°triggered¡± ?although the distortions are not as bad ? ? Tom, ? That is also why MIL-STD-461 CE102 requires a 20dB Pad on the signal path from the LISN to the Receiver. They do not recommend a Limiter due to non-linearities that Lothar points out. ? Limiters can really hurt the Noise Figure of a receiver input at well. ? Ross ? ? Limiters are very commonly recommended for Conducted Immunity testing in EMC labs where the Spec An input comes from the Line Impedance Stabilization Network (LISN) because the turn on/off transients can be quite high. The levels expected to be measured typically should be much less than the distortion level of the limiter. The recommended limiter in this case actually has an intentional 10 dB insertion loss. ? ? ? A few words about limiters , Generally limiters are used in systems to protect receivers usually in RADAR or EW applications ,? in test systems the use of limiters s usually frowned upon ( with very few exceptions)? and for good reason ! First of there is a cost penalty that is not insignificant , the cost for a connectorized limiter usually starts at about $600 and can go up into the $2K range . Limiters also degrade VSWR and add additional system loss . But the by far biggest problem is that limiters are non linear devices and as such excellent harmonics generators , harmonics will start to occur before the limiter hits the hard threshold and worsens as the power increases so if you put one in front a spectrum analyzer you have to be cautious not to end up with tst results that are worse than they actually are ? ? Mini-Circuits sells limiters as well as DC blocks, but they only go up to 8 GHz.? Not sure about the price, but they are most likely competitive.? Assuming you actually need one. ------ Original Message ------ Sent: 3/20/2022 6:52:14 AM Subject: Re: [HP-Agilent-Keysight-equipment] Protecting Equipment It's worth adding that a DC block only provides some measure of safety. The ramp up voltage of a DC signal is an AC signal and can pass right through your series cap. If you look at DC blocking filter designs like the HP 3048A option K23, there's a limiter after the series cap. It seems like the "right" devices for this sort of thing are RF power limiters. Unfortunately, the cost of many of these devices new from reputable manufacturers probably matches or exceeds what many people paid for their second-hand spectrum analyzer. Maybe there are good second-hand market options, but I haven't looked into to it. If you want something to reliably protect a low frequency SA, that shouldn't be too hard to design and build. But, if you want to get the full 22 GHz range out of your 8566, I expect that wouldn't be so easy.
|
toggle quoted message
Show quoted text
On Mar 21, 2022, at 19:52, n8zmTWH via groups.io <n8zmTWH@...> wrote:
?
What Frequencies?
?
?
?
?
Agilent E8257D 20GHz Signal generator ?, N9030A 50GHz spectrum analyzer , power sweep in 0.5Db steps from 0 to 30dBm CW
?
?
³¢´Ç³Ù³ó²¹°ù¡
?
What test gear did you use for the power sweep and what were the test points? I have a couple here I¡¯d like to compare.
?
?
?
Years ago I had this discussion with a PhD student ,? his argument was that the limiter doesn¡¯t matter unless it is triggered so I set up a experiment doing a power sweep of the limiter and capturing the output spectrum for each point ,?
he was quite surprised
?
?
Lothar,
?
Correct. The same thing happens with Zeners below 6.2V and TVS Diodes (way too much Capacitance for RF Applications).
?
Look at the Breakover point of the RF Limiter (or TVS), it is a curve. Its Impedance changes below the breakover voltage as current flows through it and approaches the knee. If it is not specified, it can be obtained via a Curve Tracer
or manually generated I-V Curves that you can produce with a simple Power Supply UUT and Resistance Standard or Resistance Decade.
?
Many Signal Integrity issues develop when they are not used properly and the curve is well understood.
?
Ross
?
?
What many people seem to forget is the fact that the non linear behavior of a limiter kicks in way before the limiter is actually ¡°triggered¡± ?although the distortions are not as bad
?
?
Tom,
?
That is also why MIL-STD-461 CE102 requires a 20dB Pad on the signal path from the LISN to the Receiver. They do not recommend a Limiter due to non-linearities that Lothar points out.
?
Limiters can really hurt the Noise Figure of a receiver input at well.
?
Ross
?
?
Limiters are very commonly recommended for Conducted Immunity testing in EMC labs where the Spec An input comes from the Line Impedance Stabilization Network (LISN) because the
turn on/off transients can be quite high. The levels expected to be measured typically should be much less than the distortion level of the limiter. The recommended limiter in this case actually has an intentional 10 dB insertion loss.
?
?
?
A few words about limiters ,
Generally limiters are used in systems to protect receivers usually in RADAR or EW applications ,? in test systems the use of limiters s usually frowned upon ( with very few exceptions)? and for good reason !
First of there is a cost penalty that is not insignificant , the cost for a connectorized limiter usually starts at about $600 and can go up into the $2K range .
Limiters also degrade VSWR and add additional system loss .
But the by far biggest problem is that limiters are non linear devices and as such excellent harmonics generators , harmonics will start to occur before the limiter hits the hard threshold and worsens as the power increases so if you put
one in front a spectrum analyzer you have to be cautious not to end up with tst results that are worse than they actually are
?
?
Mini-Circuits sells limiters as well as DC blocks, but they only go up to 8 GHz.? Not sure about the price, but they are most likely competitive.? Assuming you actually need
one.
------ Original Message ------
Sent: 3/20/2022 6:52:14 AM
Subject: Re: [HP-Agilent-Keysight-equipment] Protecting Equipment
It's worth adding that a DC block only provides some measure of safety. The ramp up voltage of a DC signal is an AC signal and can pass right through your series cap. If you
look at DC blocking filter designs like the HP 3048A option K23, there's a limiter after the series cap. It seems like the "right" devices for this sort of thing are RF power limiters. Unfortunately, the cost of many of these devices new from reputable manufacturers
probably matches or exceeds what many people paid for their second-hand spectrum analyzer. Maybe there are good second-hand market options, but I haven't looked into to it. If you want something to reliably protect a low frequency SA, that shouldn't be too
hard to design and build. But, if you want to get the full 22 GHz range out of your 8566, I expect that wouldn't be so easy.
|
toggle quoted message
Show quoted text
From: [email protected] <[email protected]> On Behalf Of Lothar baier
Sent: Monday, March 21, 2022 8:01 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Protecting Equipment? Agilent E8257D 20GHz Signal generator ?, N9030A 50GHz spectrum analyzer , power sweep in 0.5Db steps from 0 to 30dBm CW ? ? ³¢´Ç³Ù³ó²¹°ù¡ ? What test gear did you use for the power sweep and what were the test points? I have a couple here I¡¯d like to compare. ? ? ? Years ago I had this discussion with a PhD student ,? his argument was that the limiter doesn¡¯t matter unless it is triggered so I set up a experiment doing a power sweep of the limiter and capturing the output spectrum for each point ,? he was quite surprised ? ? Lothar, ? Correct. The same thing happens with Zeners below 6.2V and TVS Diodes (way too much Capacitance for RF Applications). ? Look at the Breakover point of the RF Limiter (or TVS), it is a curve. Its Impedance changes below the breakover voltage as current flows through it and approaches the knee. If it is not specified, it can be obtained via a Curve Tracer or manually generated I-V Curves that you can produce with a simple Power Supply UUT and Resistance Standard or Resistance Decade. ? Many Signal Integrity issues develop when they are not used properly and the curve is well understood. ? Ross ? ? What many people seem to forget is the fact that the non linear behavior of a limiter kicks in way before the limiter is actually ¡°triggered¡± ?although the distortions are not as bad ? ? Tom, ? That is also why MIL-STD-461 CE102 requires a 20dB Pad on the signal path from the LISN to the Receiver. They do not recommend a Limiter due to non-linearities that Lothar points out. ? Limiters can really hurt the Noise Figure of a receiver input at well. ? Ross ? ? Limiters are very commonly recommended for Conducted Immunity testing in EMC labs where the Spec An input comes from the Line Impedance Stabilization Network (LISN) because the turn on/off transients can be quite high. The levels expected to be measured typically should be much less than the distortion level of the limiter. The recommended limiter in this case actually has an intentional 10 dB insertion loss. ? ? ? A few words about limiters , Generally limiters are used in systems to protect receivers usually in RADAR or EW applications ,? in test systems the use of limiters s usually frowned upon ( with very few exceptions)? and for good reason ! First of there is a cost penalty that is not insignificant , the cost for a connectorized limiter usually starts at about $600 and can go up into the $2K range . Limiters also degrade VSWR and add additional system loss . But the by far biggest problem is that limiters are non linear devices and as such excellent harmonics generators , harmonics will start to occur before the limiter hits the hard threshold and worsens as the power increases so if you put one in front a spectrum analyzer you have to be cautious not to end up with tst results that are worse than they actually are ? ? Mini-Circuits sells limiters as well as DC blocks, but they only go up to 8 GHz.? Not sure about the price, but they are most likely competitive.? Assuming you actually need one. ------ Original Message ------ Sent: 3/20/2022 6:52:14 AM Subject: Re: [HP-Agilent-Keysight-equipment] Protecting Equipment It's worth adding that a DC block only provides some measure of safety. The ramp up voltage of a DC signal is an AC signal and can pass right through your series cap. If you look at DC blocking filter designs like the HP 3048A option K23, there's a limiter after the series cap. It seems like the "right" devices for this sort of thing are RF power limiters. Unfortunately, the cost of many of these devices new from reputable manufacturers probably matches or exceeds what many people paid for their second-hand spectrum analyzer. Maybe there are good second-hand market options, but I haven't looked into to it. If you want something to reliably protect a low frequency SA, that shouldn't be too hard to design and build. But, if you want to get the full 22 GHz range out of your 8566, I expect that wouldn't be so easy.
|
