nice digital RLC bridge

Hello John,

I use an HP4191A. These probably don't cost that much anymore on EBay but lifting one for service is a perfect recipe for a back pain. Goes to a GHz though.

I was thinking more of low frequency stuff, transformers and power inductors and things that tend to confuse cheap LC meters. The AADE thing is fine for most low-value stuff, pF and nH range. And I can always use my 20 GHz TDR!

John

Just found this one...

which seems to be a real bridge, not just a hokey lc meter. They usually make pretty good stuff. $179 is worth a try.

John

I bought one of those about two months ago. It tests at two frequencies, 120 Hz and 1 kHz. It seems pretty nice, but the accuracies claimed range from about 1% to 10%, which doesn't seem as good as the one on the link you provided.

-- John

Well, I would have thought you'd be interested in higher frequencies. The real McCoy, IMHO, is the 4275A, working from 10kHz to 10MHz, and available on eBay for about $2k. But the way you're talking, you want a 4274A, for 100Hz to 100kHz, $1k. These precision beasts, with their 4-terminal Kelvin-connector accessories, are truly the real McCoy. Or you can get an 4192A, 10Hz to 13MHz for $3.3k.* eBay is your friend.

• For manual use, the 4192A has a fatal frequency-calibration flaw. Unlike the 4174A, etc., it doesn't store all its cal values, SFAICT.

John, do you have an older HP catalog to read these instrument's datasheets, or shall I post them for you?

The AADE handheld is fine for low-value Ls and Cs. It'll resolve 1 nH and 0.1 pF, as I recall.

Actually, I have HP, Tek, and GR catalogs with pretty-much continuous coverage from the mid-1950's. But I really don't need a lot of precision for measuring signal and power transformers and inductors... even 5% would do most of the time. The true inductance of a big old laminated-iron-core transformer is sort of a nebulous concept anyhow.

I do have an old manual AC RLC bridge, but it's a real nuisance to use with sliding-null low-Q inductors. The little handheld Extech looks cool... I'll get one and try it. I'm not enthusiastic about another

Thanks,

John

John,

Stanford Research has ( or used to have ) the SR715 RLC meter. Nice.

Jure Z.

Isn't that why OrthoNull was invented?

Yes, but it didn't work very well. Microprocessors are smarter than gears.

John

Hello Win,

Did it always do that? If not then check the battery and the ROM sockets. My HP4191A developed "forgetfulness" and eventually wouldn't calibrate correctly. The first problem was related to the NiCd backup pack which had actually started leaking. The 2nd issue was related to poor sockets for the ROMs. I couldn't believe it. They used expensive ceramic ROM chips in el-cheapo sockets.

Oh, and it had a rather dirty reset. Reset circuits didn't seem to be their forte.

Hello Win,

Forgot a thing: A while ago you were soliciting suggestions what to include in the next AoE. After a discussion on a German NG it dawned on me that many (if not most) engineers do not properly understand how triacs work and how to control them. You know, the usual. Quadrants, gate drive levels, what causes erratic operation, pathologies.

Have a look on ebay at item 190030384711 and item 190030722104.

Expensive ones:

Don't know abut price:

Moderate price:

Are you trying to say that teeth are a "bit" old???

I love 4 quadrant triacs.

yeah, a poor mans ac switch!..