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Looking for help with an HP 8554B spectrum analyzer plugin
Greetings...
I don't know where to ask this, so I'm shooting for multiple groups. I purchased an HP 140T mainframe plus spectrum analyzer plugins, including the 8554B mentioned in the subject, at a hamfest. It turns out that it is working but is quite "deaf." From asking around I have been told that this is a common problem for this plugin and the culprit is the first mixer. Well... the first mixer is an upconverter to 3 GHz, and one of those magical microwave "cans" that make no sense to those of us used to thinking in lower frequencies. The only semiconductors in the can are a pair of diodes, back to back, with the designation "385" on them. HP weenies have suggested that it could be short for 1901-0385, but that part number turns up very few references, and none with the nature of the diodes and their operating characteristics. So I'm wondering if anyone out there knows what type of diodes these are likely to be and what kind of characteristics I should be looking for in replacement parts. Does anyone know anything about this dinosaur? Any help would be appreciated. Oh, BTW, the rest of the analyzer and frame work fine. I'm using a borrowed 8553B plugin with it now and getting the results I'd hoped for. While I don't plan on doing any critical work with it, the 8554B is a more capable plugin and I do have to return the borrowed one... Thanks much! -- Eric F. Richards, "Nature abhors a vacuum tube." -- J. R. Pierce, Bell Labs, c. 1940 |
You might be able to substitute them with 1N5711s. It looks like somebody
must have accidently transmitted into this unit. You can find these plug-ins at hamfests in the 50 to 100 dollar range now, but the 5711s might at least get you started. Pete Eric F. Richards wrote in message ... Greetings... I don't know where to ask this, so I'm shooting for multiple groups. I purchased an HP 140T mainframe plus spectrum analyzer plugins, including the 8554B mentioned in the subject, at a hamfest. It turns out that it is working but is quite "deaf." From asking around I have been told that this is a common problem for this plugin and the culprit is the first mixer. Well... the first mixer is an upconverter to 3 GHz, and one of those magical microwave "cans" that make no sense to those of us used to thinking in lower frequencies. The only semiconductors in the can are a pair of diodes, back to back, with the designation "385" on them. HP weenies have suggested that it could be short for 1901-0385, but that part number turns up very few references, and none with the nature of the diodes and their operating characteristics. So I'm wondering if anyone out there knows what type of diodes these are likely to be and what kind of characteristics I should be looking for in replacement parts. Does anyone know anything about this dinosaur? Any help would be appreciated. Oh, BTW, the rest of the analyzer and frame work fine. I'm using a borrowed 8553B plugin with it now and getting the results I'd hoped for. While I don't plan on doing any critical work with it, the 8554B is a more capable plugin and I do have to return the borrowed one... Thanks much! -- Eric F. Richards, "Nature abhors a vacuum tube." -- J. R. Pierce, Bell Labs, c. 1940 |
You might be able to substitute them with 1N5711s. It looks like somebody
must have accidently transmitted into this unit. You can find these plug-ins at hamfests in the 50 to 100 dollar range now, but the 5711s might at least get you started. Pete Eric F. Richards wrote in message ... Greetings... I don't know where to ask this, so I'm shooting for multiple groups. I purchased an HP 140T mainframe plus spectrum analyzer plugins, including the 8554B mentioned in the subject, at a hamfest. It turns out that it is working but is quite "deaf." From asking around I have been told that this is a common problem for this plugin and the culprit is the first mixer. Well... the first mixer is an upconverter to 3 GHz, and one of those magical microwave "cans" that make no sense to those of us used to thinking in lower frequencies. The only semiconductors in the can are a pair of diodes, back to back, with the designation "385" on them. HP weenies have suggested that it could be short for 1901-0385, but that part number turns up very few references, and none with the nature of the diodes and their operating characteristics. So I'm wondering if anyone out there knows what type of diodes these are likely to be and what kind of characteristics I should be looking for in replacement parts. Does anyone know anything about this dinosaur? Any help would be appreciated. Oh, BTW, the rest of the analyzer and frame work fine. I'm using a borrowed 8553B plugin with it now and getting the results I'd hoped for. While I don't plan on doing any critical work with it, the 8554B is a more capable plugin and I do have to return the borrowed one... Thanks much! -- Eric F. Richards, "Nature abhors a vacuum tube." -- J. R. Pierce, Bell Labs, c. 1940 |
"Eric F. Richards" wrote:
Greetings... I don't know where to ask this, so I'm shooting for multiple groups. I purchased an HP 140T mainframe plus spectrum analyzer plugins, including the 8554B mentioned in the subject, at a hamfest. It turns out that it is working but is quite "deaf." From asking around I have been told that this is a common problem for this plugin and the culprit is the first mixer. Well... the first mixer is an upconverter to 3 GHz, and one of those magical microwave "cans" that make no sense to those of us used to thinking in lower frequencies. The only semiconductors in the can are a pair of diodes, back to back, with the designation "385" on them. HP weenies have suggested that it could be short for 1901-0385, but that part number turns up very few references, and none with the nature of the diodes and their operating characteristics. These *might* be microwave mixer diodes, like the 1N416D, for example. The thing to look for is noise figure. I have a 1L20 spectrum analyzer plug-in for my Tek scope, from the same era as your SA (but much much cruder). I have never seen your SA, but all I can say is that the first mixer in my 1L20 contains a single diode. Do yours look like this? http://www.dfpresource.org/1n416d.jpg If so, you might try a kludge like this: http://www.dfpresource.org/modded1n5711.jpg Worked for me. |
"Eric F. Richards" wrote:
Greetings... I don't know where to ask this, so I'm shooting for multiple groups. I purchased an HP 140T mainframe plus spectrum analyzer plugins, including the 8554B mentioned in the subject, at a hamfest. It turns out that it is working but is quite "deaf." From asking around I have been told that this is a common problem for this plugin and the culprit is the first mixer. Well... the first mixer is an upconverter to 3 GHz, and one of those magical microwave "cans" that make no sense to those of us used to thinking in lower frequencies. The only semiconductors in the can are a pair of diodes, back to back, with the designation "385" on them. HP weenies have suggested that it could be short for 1901-0385, but that part number turns up very few references, and none with the nature of the diodes and their operating characteristics. These *might* be microwave mixer diodes, like the 1N416D, for example. The thing to look for is noise figure. I have a 1L20 spectrum analyzer plug-in for my Tek scope, from the same era as your SA (but much much cruder). I have never seen your SA, but all I can say is that the first mixer in my 1L20 contains a single diode. Do yours look like this? http://www.dfpresource.org/1n416d.jpg If so, you might try a kludge like this: http://www.dfpresource.org/modded1n5711.jpg Worked for me. |
A E wrote:
These *might* be microwave mixer diodes, like the 1N416D, for example. The thing to look for is noise figure. I have a 1L20 spectrum analyzer plug-in for my Tek scope, from the same era as your SA (but much much cruder). I have never seen your SA, but all I can say is that the first mixer in my 1L20 contains a single diode. Do yours look like this? Not even remotely. Here's a pic of the assembly, out of the "can:" http://www.dim.com/~efricha/mixer-diodes.jpg -- Eric F. Richards, "The first rule about macros is: Don't use them unless you have to. Almost every macro demonstrates a flaw in the programming language, in the program, or in the programmer." -- Stroustrup |
A E wrote:
These *might* be microwave mixer diodes, like the 1N416D, for example. The thing to look for is noise figure. I have a 1L20 spectrum analyzer plug-in for my Tek scope, from the same era as your SA (but much much cruder). I have never seen your SA, but all I can say is that the first mixer in my 1L20 contains a single diode. Do yours look like this? Not even remotely. Here's a pic of the assembly, out of the "can:" http://www.dim.com/~efricha/mixer-diodes.jpg -- Eric F. Richards, "The first rule about macros is: Don't use them unless you have to. Almost every macro demonstrates a flaw in the programming language, in the program, or in the programmer." -- Stroustrup |
Fred Abse wrote:
On Sun, 10 Aug 2003 04:25:28 +0100, Eric F. Richards wrote: Not even remotely. Here's a pic of the assembly, out of the "can:" http://www.dim.com/~efricha/mixer-diodes.jpg AHHHHH... They're wire-ended. Go to agilent.com and have a look through their range of Schottky diodes. There's almost bound to be something there. Unfortunately I already did that, and Agilent's Big Book of Semiconductors doesn't have a listing for it. Don't take this wrong, but Usenet is kinda my last option. Or second last -- I plan on getting a photocopy of the service manual. Eric -- Eric F. Richards, "Nature abhors a vacuum tube." -- J. R. Pierce, Bell Labs, c. 1940 |
Fred Abse wrote:
On Sun, 10 Aug 2003 04:25:28 +0100, Eric F. Richards wrote: Not even remotely. Here's a pic of the assembly, out of the "can:" http://www.dim.com/~efricha/mixer-diodes.jpg AHHHHH... They're wire-ended. Go to agilent.com and have a look through their range of Schottky diodes. There's almost bound to be something there. Unfortunately I already did that, and Agilent's Big Book of Semiconductors doesn't have a listing for it. Don't take this wrong, but Usenet is kinda my last option. Or second last -- I plan on getting a photocopy of the service manual. Eric -- Eric F. Richards, "Nature abhors a vacuum tube." -- J. R. Pierce, Bell Labs, c. 1940 |
Fred Abse wrote: On Sun, 10 Aug 2003 12:34:17 +0100, A E wrote: Schottky barrier diodes like this are used in mixers all the time because of their speed (no charge storage), but from what I understand, weren't used back then because, well, they didn't exist. They've existed since the 1950s. Yes, surface barrier transistors and such used the Schottky effect in those times, but as a collector of some 60s vintage stuff, Schottky diodes are absent in these units. Every other kind of diode, Schockley, tunnel, snap, varactor, back, GaAs, Ge, etc... but not a single Schottky diode. In my 1L20 the 1N5711 performs the same as the 1N416D. So why did they use a complicated to build unit like the 416D if they had had 1N5711-style devices back then? I suppose they must have been used in the 60s because analog samplers with Schottky diodes are certainly in the literature, so maybe they were too new, expensive? Really, I'd like to know. The principle was postulated in 1938. But as a commercial product, when did Schottky diodes arrive on the market? |
Fred Abse wrote: On Sun, 10 Aug 2003 12:34:17 +0100, A E wrote: Schottky barrier diodes like this are used in mixers all the time because of their speed (no charge storage), but from what I understand, weren't used back then because, well, they didn't exist. They've existed since the 1950s. Yes, surface barrier transistors and such used the Schottky effect in those times, but as a collector of some 60s vintage stuff, Schottky diodes are absent in these units. Every other kind of diode, Schockley, tunnel, snap, varactor, back, GaAs, Ge, etc... but not a single Schottky diode. In my 1L20 the 1N5711 performs the same as the 1N416D. So why did they use a complicated to build unit like the 416D if they had had 1N5711-style devices back then? I suppose they must have been used in the 60s because analog samplers with Schottky diodes are certainly in the literature, so maybe they were too new, expensive? Really, I'd like to know. The principle was postulated in 1938. But as a commercial product, when did Schottky diodes arrive on the market? |
"Pete KE9OA" wrote:
You might be able to substitute them with 1N5711s. It looks like somebody must have accidently transmitted into this unit. You can find these plug-ins at hamfests in the 50 to 100 dollar range now, but the 5711s might at least get you started. Pete Pete, I'm probably going to have to go this way since other suggestions have appeared to be dead ends for now. Thanks for the suggestion. So... is a '5711 a high-speed Schottkey? (I know, I can look it up, but my connection is very slow right now...) Thanks, Eric -- Eric F. Richards, "This book reads like a headache on paper." http://www.cnn.com/2001/CAREER/readi...one/index.html |
"Pete KE9OA" wrote:
You might be able to substitute them with 1N5711s. It looks like somebody must have accidently transmitted into this unit. You can find these plug-ins at hamfests in the 50 to 100 dollar range now, but the 5711s might at least get you started. Pete Pete, I'm probably going to have to go this way since other suggestions have appeared to be dead ends for now. Thanks for the suggestion. So... is a '5711 a high-speed Schottkey? (I know, I can look it up, but my connection is very slow right now...) Thanks, Eric -- Eric F. Richards, "This book reads like a headache on paper." http://www.cnn.com/2001/CAREER/readi...one/index.html |
Leigh W3NLB wrote:
On Sun, 10 Aug 2003 07:34:17 -0400, A E wrote: "Eric F. Richards" wrote: A E wrote: These *might* be microwave mixer diodes, like the 1N416D, for example. The thing to look for is noise figure. I have a 1L20 spectrum analyzer plug-in for my Tek scope, from the same era as your SA (but much much cruder). I have never seen your SA, but all I can say is that the first mixer in my 1L20 contains a single diode. Do yours look like this? Not even remotely. Here's a pic of the assembly, out of the "can:" Oh well. http://www.dim.com/~efricha/mixer-diodes.jpg Sweet. Looks like a single balanced mixer with the LO injected in the coil on top? I'm way out of my league here, I'm hoping that someone in the know jumps in here, I'd like to know myself. But, I'm guessing you tested those diodes by lifting one lead and determined that they indeed are dead... Testing a microwave mixer diode using an ohmmeter will guarantee that it's dead. They make special low-current meters for testing these animals. True, I use a 1.5V cheapie analog meter for testing tunnel diodes, but in my limited experience, diodes like the 1N416D can be tested with modern DMM with no damage. But you're right, I should have recommend testing with low current anyways. |
Leigh W3NLB wrote:
On Sun, 10 Aug 2003 07:34:17 -0400, A E wrote: "Eric F. Richards" wrote: A E wrote: These *might* be microwave mixer diodes, like the 1N416D, for example. The thing to look for is noise figure. I have a 1L20 spectrum analyzer plug-in for my Tek scope, from the same era as your SA (but much much cruder). I have never seen your SA, but all I can say is that the first mixer in my 1L20 contains a single diode. Do yours look like this? Not even remotely. Here's a pic of the assembly, out of the "can:" Oh well. http://www.dim.com/~efricha/mixer-diodes.jpg Sweet. Looks like a single balanced mixer with the LO injected in the coil on top? I'm way out of my league here, I'm hoping that someone in the know jumps in here, I'd like to know myself. But, I'm guessing you tested those diodes by lifting one lead and determined that they indeed are dead... Testing a microwave mixer diode using an ohmmeter will guarantee that it's dead. They make special low-current meters for testing these animals. True, I use a 1.5V cheapie analog meter for testing tunnel diodes, but in my limited experience, diodes like the 1N416D can be tested with modern DMM with no damage. But you're right, I should have recommend testing with low current anyways. |
Fred Abse writes:
On Sun, 10 Aug 2003 04:25:28 +0100, Eric F. Richards wrote: Not even remotely. Here's a pic of the assembly, out of the "can:" http://www.dim.com/~efricha/mixer-diodes.jpg AHHHHH... They're wire-ended. Can you get a close up of the numbers? I have a junk box full of odds and ends of HP diodes. Go to agilent.com and have a look through their range of Schottky diodes. There's almost bound to be something there. -- Then there's duct tape ... (Garrison Keillor) -- Steven D. Swift, , http://www.novatech-instr.com NOVATECH INSTRUMENTS, INC. P.O. Box 55997 206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA |
Fred Abse writes:
On Sun, 10 Aug 2003 04:25:28 +0100, Eric F. Richards wrote: Not even remotely. Here's a pic of the assembly, out of the "can:" http://www.dim.com/~efricha/mixer-diodes.jpg AHHHHH... They're wire-ended. Can you get a close up of the numbers? I have a junk box full of odds and ends of HP diodes. Go to agilent.com and have a look through their range of Schottky diodes. There's almost bound to be something there. -- Then there's duct tape ... (Garrison Keillor) -- Steven D. Swift, , http://www.novatech-instr.com NOVATECH INSTRUMENTS, INC. P.O. Box 55997 206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA |
(Steven Swift) wrote:
Can you get a close up of the numbers? I have a junk box full of odds and ends of HP diodes. Not soon. The pic was taken by an experienced tech who took a look at it as a favor. I'll have to *gently* get it apart myself or ask him to do so again. He knows his way around RF but was uncomfortable working on this thing; I'm almost scared spitless. ....the joys of microwave... -- Eric F. Richards, "Nature abhors a vacuum tube." -- J. R. Pierce, Bell Labs, c. 1940 |
Should have made not of this in the previous message. The markings
appear to be HP 385. Likely part number is 1901-0385 Eric F. Richards wrote: (Steven Swift) wrote: Can you get a close up of the numbers? I have a junk box full of odds and ends of HP diodes. Not soon. The pic was taken by an experienced tech who took a look at it as a favor. I'll have to *gently* get it apart myself or ask him to do so again. He knows his way around RF but was uncomfortable working on this thing; I'm almost scared spitless. ...the joys of microwave... -- Eric F. Richards "The weird part is that I can feel productive even when I'm doomed." - Dilbert |
Should have made not of this in the previous message. The markings
appear to be HP 385. Likely part number is 1901-0385 Eric F. Richards wrote: (Steven Swift) wrote: Can you get a close up of the numbers? I have a junk box full of odds and ends of HP diodes. Not soon. The pic was taken by an experienced tech who took a look at it as a favor. I'll have to *gently* get it apart myself or ask him to do so again. He knows his way around RF but was uncomfortable working on this thing; I'm almost scared spitless. ...the joys of microwave... -- Eric F. Richards "The weird part is that I can feel productive even when I'm doomed." - Dilbert |
"Eric F. Richards" wrote in message ... Should have made not of this in the previous message. The markings appear to be HP 385. Likely part number is 1901-0385 Eric, I can confirm that this is/was the right part number. In the '70's a matched pair was ~UKP 150. You might try something like a pair of BAR28, if you can get them, (Shottky barrier - useful to 10GHz) at UKP 0.5 each IMO they would be worth trying. Good luck, -- Roger London UK. -- Remove XX for correct email address |
"Eric F. Richards" wrote in message ... Should have made not of this in the previous message. The markings appear to be HP 385. Likely part number is 1901-0385 Eric, I can confirm that this is/was the right part number. In the '70's a matched pair was ~UKP 150. You might try something like a pair of BAR28, if you can get them, (Shottky barrier - useful to 10GHz) at UKP 0.5 each IMO they would be worth trying. Good luck, -- Roger London UK. -- Remove XX for correct email address |
I haven't seen them blow out from signal generators, but I have from some of
the high output synthesizers that would put out +23dBm. It's too bad that they couldn't make a more robust mixer....................you would figure that they would be using at least a Level 17 mixer. Pete Fred Abse wrote in message news:pan.2003.08.11.19.58.05.429819.811@cerebrumco nfus.it... On Sat, 09 Aug 2003 17:52:22 +0100, Pete KE9OA wrote: It looks like somebody must have accidently transmitted into this unit. You don't need to transmit into most older analyzers. Much more than 10dBm will croak some of them. You could do that with some signal generators. BTDT -- Then there's duct tape ... (Garrison Keillor) |
I haven't seen them blow out from signal generators, but I have from some of
the high output synthesizers that would put out +23dBm. It's too bad that they couldn't make a more robust mixer....................you would figure that they would be using at least a Level 17 mixer. Pete Fred Abse wrote in message news:pan.2003.08.11.19.58.05.429819.811@cerebrumco nfus.it... On Sat, 09 Aug 2003 17:52:22 +0100, Pete KE9OA wrote: It looks like somebody must have accidently transmitted into this unit. You don't need to transmit into most older analyzers. Much more than 10dBm will croak some of them. You could do that with some signal generators. BTDT -- Then there's duct tape ... (Garrison Keillor) |
On Mon, 11 Aug 2003 21:40:39 +0100, Fred Abse
wrote: On Sat, 09 Aug 2003 17:52:22 +0100, Pete KE9OA wrote: It looks like somebody must have accidently transmitted into this unit. You don't need to transmit into most older analyzers. Much more than 10dBm will croak some of them. You could do that with some signal generators. BTDT My 8554B says "Maximum 10 dBm" on the front in big red letters. There's probably a reason why they put that on the panel. 73 de Leigh W3NLB |
On Mon, 11 Aug 2003 21:40:39 +0100, Fred Abse
wrote: On Sat, 09 Aug 2003 17:52:22 +0100, Pete KE9OA wrote: It looks like somebody must have accidently transmitted into this unit. You don't need to transmit into most older analyzers. Much more than 10dBm will croak some of them. You could do that with some signal generators. BTDT My 8554B says "Maximum 10 dBm" on the front in big red letters. There's probably a reason why they put that on the panel. 73 de Leigh W3NLB |
I think it must go back to what devices were available at that time; my
8558B specifies no more than +30dBm. Pete Leigh W3NLB wrote in message ... On Mon, 11 Aug 2003 21:40:39 +0100, Fred Abse wrote: On Sat, 09 Aug 2003 17:52:22 +0100, Pete KE9OA wrote: It looks like somebody must have accidently transmitted into this unit. You don't need to transmit into most older analyzers. Much more than 10dBm will croak some of them. You could do that with some signal generators. BTDT My 8554B says "Maximum 10 dBm" on the front in big red letters. There's probably a reason why they put that on the panel. 73 de Leigh W3NLB |
I think it must go back to what devices were available at that time; my
8558B specifies no more than +30dBm. Pete Leigh W3NLB wrote in message ... On Mon, 11 Aug 2003 21:40:39 +0100, Fred Abse wrote: On Sat, 09 Aug 2003 17:52:22 +0100, Pete KE9OA wrote: It looks like somebody must have accidently transmitted into this unit. You don't need to transmit into most older analyzers. Much more than 10dBm will croak some of them. You could do that with some signal generators. BTDT My 8554B says "Maximum 10 dBm" on the front in big red letters. There's probably a reason why they put that on the panel. 73 de Leigh W3NLB |
you might be better of using a modern SMD dual schottky diode, better
match, lower capacitance etc. You will have to devise some neat way of fitting them in. Circuit is in series config so try HSMS-2814, or 2 in one package HSMS-2815. Try Farnell or Newark? for these parts.Yes the service manual says you need a matched pair of 1902-0385. I suspect a pair of 5082-2835 would do OK also. Eric F. Richards wrote: Greetings... I don't know where to ask this, so I'm shooting for multiple groups. I purchased an HP 140T mainframe plus spectrum analyzer plugins, including the 8554B mentioned in the subject, at a hamfest. It turns out that it is working but is quite "deaf." From asking around I have been told that this is a common problem for this plugin and the culprit is the first mixer. Well... the first mixer is an upconverter to 3 GHz, and one of those magical microwave "cans" that make no sense to those of us used to thinking in lower frequencies. The only semiconductors in the can are a pair of diodes, back to back, with the designation "385" on them. HP weenies have suggested that it could be short for 1901-0385, but that part number turns up very few references, and none with the nature of the diodes and their operating characteristics. So I'm wondering if anyone out there knows what type of diodes these are likely to be and what kind of characteristics I should be looking for in replacement parts. Does anyone know anything about this dinosaur? Any help would be appreciated. Oh, BTW, the rest of the analyzer and frame work fine. I'm using a borrowed 8553B plugin with it now and getting the results I'd hoped for. While I don't plan on doing any critical work with it, the 8554B is a more capable plugin and I do have to return the borrowed one... Thanks much! |
you might be better of using a modern SMD dual schottky diode, better
match, lower capacitance etc. You will have to devise some neat way of fitting them in. Circuit is in series config so try HSMS-2814, or 2 in one package HSMS-2815. Try Farnell or Newark? for these parts.Yes the service manual says you need a matched pair of 1902-0385. I suspect a pair of 5082-2835 would do OK also. Eric F. Richards wrote: Greetings... I don't know where to ask this, so I'm shooting for multiple groups. I purchased an HP 140T mainframe plus spectrum analyzer plugins, including the 8554B mentioned in the subject, at a hamfest. It turns out that it is working but is quite "deaf." From asking around I have been told that this is a common problem for this plugin and the culprit is the first mixer. Well... the first mixer is an upconverter to 3 GHz, and one of those magical microwave "cans" that make no sense to those of us used to thinking in lower frequencies. The only semiconductors in the can are a pair of diodes, back to back, with the designation "385" on them. HP weenies have suggested that it could be short for 1901-0385, but that part number turns up very few references, and none with the nature of the diodes and their operating characteristics. So I'm wondering if anyone out there knows what type of diodes these are likely to be and what kind of characteristics I should be looking for in replacement parts. Does anyone know anything about this dinosaur? Any help would be appreciated. Oh, BTW, the rest of the analyzer and frame work fine. I'm using a borrowed 8553B plugin with it now and getting the results I'd hoped for. While I don't plan on doing any critical work with it, the 8554B is a more capable plugin and I do have to return the borrowed one... Thanks much! |
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