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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) |
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! |
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