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8566 5.2V supply

Francesco Ledda All Messages By This Member #121847 开云体育 All, ? I have an 8566 with a problematic 5.2V supply. ? Its schematic shows? a couple of transistors that seem not have commercial replacements. The xref I have here doesn’t show those PNs. ? These are: 1854-0404 and 1854-0441 ? Can anybody help me out? ? Best, Francesco K5URG
RubenRubio All Messages By This Member #121865 Hello Francesco ? In my xref lists I cannot found equivalent, so I did some google search about 1854-0404. Mr. Terrell wrote here in this forum:? ?"Michael A. Terrell 25.11.2018???#92882?? My notes suggest a 2N3904. "1854-1293 as per Keysight as replacement for 1854-0071 . Part Description: Mod and Ser Nbr Reqd Transistor NPN VCE-25V IC-0.1A PD-0.625W silicon TO-92, Protected Supply 1854-0071 was a generic small signal NPN silicon transistor that was usuallly used wherever a grunt NPN was needed. A 2N3904 would be a good replacement. 1854-0404 was the same device but in a metal can." Michael A. Terrell" And for the 1854-0441 I found this web page, that sugest it is a diode and shows some p/n: Maybe this can help you ? Regards, Ruben
Francesco Ledda All Messages By This Member #121870 开云体育 Thank you!!! toggle quoted message Show quoted text On Jan 20, 2022, at 02:20, RubenRubio <rubenrb2019@...> wrote: ? Hello Francesco ? In my xref lists I cannot found equivalent, so I did some google search about 1854-0404. Mr. Terrell wrote here in this forum:? ?"Michael A. Terrell 25.11.2018???#92882?? My notes suggest a 2N3904. "1854-1293 as per Keysight as replacement for 1854-0071 . Part Description: Mod and Ser Nbr Reqd Transistor NPN VCE-25V IC-0.1A PD-0.625W silicon TO-92, Protected Supply 1854-0071 was a generic small signal NPN silicon transistor that was usuallly used wherever a grunt NPN was needed. A 2N3904 would be a good replacement. 1854-0404 was the same device but in a metal can." Michael A. Terrell" And for the 1854-0441 I found this web page, that sugest it is a diode and shows some p/n: Maybe this can help you ? Regards, Ruben
Bruce All Messages By This Member #121872 The 1854-0441 is NOT a diode. All 1854-.... parts are NPN transistors Cheers! Bruce Quoting RubenRubio <rubenrb2019@...>: toggle quoted message Show quoted text Hello Francesco In my xref lists I cannot found equivalent, so I did some google search about 1854-0404. Mr. Terrell wrote here in this forum: "Michael A. Terrell 25.11.2018 #92882 ( /g/HP-Agilent-Keysight-equipment/message/92882 ) My notes suggest a 2N3904. "1854-1293 as per Keysight as replacement for 1854-0071 . Part Description: Mod and Ser Nbr Reqd Transistor NPN VCE-25V IC-0.1A PD-0.625W silicon TO-92, Protected Supply 1854-0071 was a generic small signal NPN silicon transistor that was usuallly used wherever a grunt NPN was needed. A 2N3904 would be a good replacement. 1854-0404 was the same device but in a metal can." Michael A. Terrell" And for the 1854-0441 I found this web page, that sugest it is a diode and shows some p/n: click here ( ) Maybe this can help you Regards, Ruben
benj3867 All Messages By This Member #122395 A bit of a late reply, but I hope it is still of value. The 1854-0441 was used as Q4 on the A17 boards for instruments with serial number prefixes in the range 2410A to 2532A. It is a general purpose power NPN transistor in a TO-3 package. In later instruments it was replaced --- without changing, to the best of my knowledge, any of the surrounding components --- with a TIP41A transistor which comes in a modern TO-220 package. Thus, if you need to replace the 1854-0441 either go for a TIP41A (in which case you will need to accommodate the different footprint and replace/modify the small heat-sink), or look at the TIP41A specs and locate a reasonable replacement in a TO-3 package, which should not be hard.? Note that even though these are power transistors they are dissipating well below their rated maximum power in this circuit as they are mounted on tiny heat-sinks.

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