HP 8546A spectrum analyzer AUX cable pin-out  - Page 1
Forum section: electronics / repair

author: ArjenCNX
author_rank: Contributor
timestamp: March 09, 2020, 07:55:45 am
content: Hi there all, i just purchased a HP 8546A EMI receiver, it came without connectors or cables and with those pesky Rifa X2 boogers, that managed to "pop" after turning it on with my variac in place.I hope someone can do me the honors and check the pin-out of the AUX interconnect sub-D 9 pin male to sub-D 9 pin female (assuming i correctly assumed their genders)Its just 9 pins, i know but it's bitten me in the ass before, so i hope someone out there can lend a hand and help me identify the pin out. the HP part number of this cable is HP 8120-6337, i cannot find anything online.Otherwise there is not a spec of dust in the thing, CRT is crisp as can be, the unit has seen very little hot suppers, should serve us well in the future and is 9HZ~6.5GHZ.Thanks in advance,Arjen

author: ArjenCNX
author_rank: Contributor
timestamp: March 09, 2020, 09:11:23 am
content: After some more Digging, i have actually found the right pin out, so here it is, for future reference for all to use.seems we do have some more issues with this beast, the 30MHZ signal i gave it shows up at 69mhz, and the mirror peak is at about 100 MHZ.... happy digging. if anyone has any advice, im all ears.

author: ArjenCNX
author_rank: Contributor
timestamp: March 09, 2020, 09:12:55 am
content: While i'm at it, here is the service manual as well.https://doc.xdevs.com/doc/HP_Agilent_Keysight/HP%2085422E,%208542E,%2085462A,%208546A%20%20Reference.pdf

author: ArjenCNX
author_rank: Contributor
timestamp: March 10, 2020, 08:38:19 am
content: Allright, update on the HP8546, it seems my narrowband IF board (08590-60352) has a blown tantalum on it and the issue seems to be on this board. if anyone has schematics of this board, or wants to sell a replacement, id be more than happy.Thanks!

author: ArjenCNX
author_rank: Contributor
timestamp: March 16, 2020, 10:44:49 am
content: Allright, next step,Unit runs well now but gives a error code, CAL: RES BW AMPL FAIL that is normally caused by a faulty board, the RF Narrow Band RBW 08590-60352. (this was the board with a blown tantalum cap on the plus power line of the op-amp, i replaced the capacitor with a ceramic SMD one since this is the Vcc line, it should not influence the signals)After replacing the faulty op-amp on the PCB, MC33282D and replaced it with the TL072 ( all i could get here for now) i still get the same error when i calibrate the unit.So the Question is weather i should replace the whole board, or whether there are any other ways to repair the current board. i did not find any more info on this board, no schematics.Any grey bearded brethren dare comment?

author: ArjenCNX
author_rank: Contributor
timestamp: March 16, 2020, 10:53:50 am
content: Some pics, the machine is in good nick, looks to me it has not been used much, no dust, not a spec inside.

author: langlv
author_rank: Contributor
timestamp: March 15, 2021, 01:55:46 pm
content: Hello ArjenCNX,since you have the DB9 cable, that means you have the HP 85460A RF filter attached to the HP85461A receiver.I had the same error, turn out that in the RF filter module, there are 4 RF relays having theirs flex cables disconnected from the main board. The design is similar to the HP 85685A preselector for 8566 spectrum analyzer.Good luck.Lang