Advantest U4341 RF Field Analyzer - peek inside - Page 1
Forum section: electronics / testgear

author: vutt
author_rank: Contributor
timestamp: May 12, 2022, 06:51:46 pm
content: Decided to graduate from "LTDZ 35-4400M" level USB Spectrum analyzer devices and find reasonably priced bench one which would help me grow in RF area. In my country in EU second hand local market for SA is non existent so I opted for Japan import. While I won auction in nice $250-ish price bracket I had to pay as much on top because Japanese seller packed it safe in over padded XXXL format. So oversized shipping cost and double VAT went out from my comfort zone...Still I'm happy with my very first proper SA. No functional issues despite the fact that chip dating on boards suggest late 96/97-ish manufacturing date.Despite the fact that it's called RF Field Analyzer it is fully functional SA. Pity that TG is missing, but I have already ordered ultra cheap noise generator from china to compensate.If I'm not mistaken than U-series is meant for portable work. According to manual it has battery option. Entire PSU is detachable. Unfortunately included PSU has small whiny fan inside (I disassembled it and cleaned from dust - pic attached). It has XLR type of connector for external DC power supply so I could use modern silent replacement. Still from noise angle unit own fan is even louder. I guess this is one of the major downsides compared to modern power efficient SA-s.It has internal soldered Lithium battery on one of those addon type of cards. Measured voltage - 3.68 so all good.One of the attraction of this unit is build in analog TV modulation option. I'm also little into into retro gear (like this one) so ability to troubleshoot TV signal might come handily. It is actually capable showing TV picture on that TFT screen. I do not have 75->50 ohm adapter yet to test it as of yet.I like the design. Screen can be tilted. Everything inside is modular. Front panel actually slides into socket and even slide in addon cards have nice convenient loop for finger so one can pull out cards with minimal effort. 80,90-ies tech have robustness build quality charm I have to admit. This is mobile unit which have seen I assume a lot of going about in his life as trusty TV technician tool and it still works after 20+ years.I also added spec sheet.pdf for those "playing along at home" as wise man tend to say...

author: vutt
author_rank: Contributor
timestamp: May 14, 2022, 11:36:23 am
content: I'm having trouble demodulating PAL TV UHF signal. It's might be down to my lack of knowledge. My only experience with TV signal have been back in the days where it was very popular to create sound carrier conversion module for Soviet SECAM TV-s in order to receive Finnish PAL sound across the border. Of course we even could not dream to use this kind of cool gear for signal analysis.So I have verified that PAL video signal decoder is in working condition. Direct video in from my MSX computer is working (pic attached).However when switching to MSX RF out -> SA RF in signal appears just fine (attached pic) however demodulation is not working. Just slightly different scrambled picture with noise compared to no signal static. And SA is set up to receive PAL signal from config.Looking at SA signal shouldn't there be distinct audio carrier peak visible? Also those peak beyond 8Mhz span I assume are not part of signal. Some sort of harmonics or something is bleeding over from MSX RF modulator.Another issue might be SA input impedance mismatch. I do not have 75->50 ohm adapter. 56 dmµV might be to weak signal to decode.Like I said I'm beginner so any ideas are welcome.

author: autoelectra
author_rank: Contributor
timestamp: August 13, 2023, 08:26:11 am
content: Dear Vutt,nice report . I have the U4941, which is very similiar to your model.(Without TV-Card)I don't know if it helps, but mine had a lot of capacitors that leaked.So, please check the capacitors on the TV card and elsewhere.My main power supply on the Backside started delayed or not at all, a brown electrolytic capacitor inside the black box near the pulse width IC had leaked.I noticed that your DC board, it provides 8V,12V,-12V,-8V,5V (the right one of your picture) is missing a shield box, my card is completely enclosed by the sheet metal.Did you get schematics?My one has error 900 lock det, the troubleshooting guide here from the U3661 does not help, since different RF board.