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The 334 has an Automatic Nulling (A6 board) circuit which uses lamps and a single detector. I see no chopper.

I haven't used it in a while, I've been using a leader LDM-170 but feel more confident in triusting the 334A. First problem is that you can't "Set" anything unless you have an extremely high voltage

Guys, Just in case it helps, the names Marconi Instruments / IFR / Aeroflex / Cobham / Viavi are all historical parts of the same company from 1998 onwards. With regards to IFR, this operation was/is

Hi Roy, /g/Marconi-Test-Instruments I have been getting some good information there. Dave wrote: -- 72 de Dave VE7HR

Hi Dave: If you could post the links you found, that would be great. There appears to be many things associated with the names IFR and Aeorflex Cheers and best wishes. Roy

I didn't mean to sound critical but I think I did, my apologies. The lack of mercury cells is a PITA. Lots of stuff used them and its often hard to find a substitute.

Thanks, all! I forgot about the Auto Null function.

What a mess and unfortunately it happens. In addition to the various cleaning hints at least with nicad batteries I have found they do leave conductive stuff. Even though the boards been cleaned. In

excuse my mistake, I have done restoration 427A and 204B side by side on the table. The 22.5V Battery is correct. Can be swapped by 2 pcs of 9V Blocks lithium for backup light , they deliver 10.2V

Yes!!! You are a truffle pig! Tam With best regards Tam HANNA Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at https://www.instagram.com/tam.hanna/

Is it the video on the HP 419 meter? "https://youtu.be/vrmwql2msbU"

You are right, there are 3 CdS cells, and two lamps that are used to operate a Wein bridge that performs the auto null function. The last 334 that was in my shop had one bad CdS cell, and the bridge

Well to be fair, yours was a pretty general question that certainly applies here too. -Dave

Jeremy, Auto null. The neons and light sensitive resistors are used in a Wien bridge to automatically balance the null. Page 4.2 onwards describes the circuit in detail. Loss of a neon and its back to

Original battery is 22.5V. They are available but expensive. I made a battery pack using two 8 cell battery holders for AA cells and left one cell out putting a wire in place of the battery. probably

Jeremy, Auto null. ------ Best regards, Goran Finnberg The Mastering Room AB Goteborg Sweden E-mail: mastering@... Learn from the mistakes of others, you can never live long enough to make them

Unless my memory is failing, it's not strictly a chopper, but it's part of the automatic tuning system. The choppers are digitally-controlled switches, but I believe the LDR-based subsystem in the 33x

Purely out of curiosity, what is the purpose of a chopper in a 334 distortion analyzer? HP used choppers in a lot of their DC voltmeters to convert the DC to AC. They’d run the AC through some

hello Dave, yes, specials: The Power Line Supply is a Option and not always inside. 427A have a Set of 4 obsolete 6.75V mercury batterys, if they are tired and there is no PSU, build it self. The

Hello, a dude named CarlsonLabs has had a 2h video on replacing these neons. Never sat through it all the way to the fartingsound, don?t have a link handy but wanted to mention it. If there is