Author Topic: Suggestion on decade resistor? (Read 4056 times)

branadic · « **on:** July 14, 2018, 07:49:46 pm »

Currently I'm interested in buying a 7 dial decade resistor. Several offers on ebay are available, but I would like some feedback:

I wonder if someone here has a Beckman 71-DRK 7 Precision Decade Resistor box and can say something about it? Are there any teardown pictures available? What are the specifications?

Pictures and datasheet of a General Radio Type 1434-G - Decade Resistors can be found on internet, but what is such a unit worth and what to look after?

-branadic-

branadic · « **Reply #1 on:** July 22, 2018, 06:47:44 pm »

Decided for the General Radio Type 1434-G and made an offer to the seller that was accepted. So now I need to wait for the unit to arrive.

-branadic-

Henrik_V · « **Reply #2 on:** July 22, 2018, 07:56:24 pm »

And it seems to be a genuine GR !

gbaddeley · « **Reply #3 on:** July 23, 2018, 11:53:02 am »

0.02%, nice. The GR looks much better than the crusty Beckman.

branadic · « **Reply #4 on:** July 23, 2018, 05:13:48 pm »

Quote

0.02%, nice. The GR looks much better than the crusty Beckman.

Look is one thing, but what matters are the intrinsic values. I have hoped to get some info on the Beckman to learn about it's accuracy and T.C.

-branadic-

branadic · « **Reply #5 on:** July 31, 2018, 09:49:51 am »

My decade resistor box arrived today, much earlier than expected. It's in reasonable condition by the looks of it, a few new switch caps would be fine. Do IET sale them as spare parts?
Need to test it first at home and afterward on our 3458A. First of all, time to brake the cal stickers on it and check if everything inside looks okay.
If you guys need one unit, there are two left. Just place an offer to the seller

EDIT: No overload visible inside and a first sanity check on my Prema 5000 shows very good results, that have to be verified on 3458A. Cleaned the unit, removed old sticker and dirt on the panel.

-branadic-

Conrad Hoffman · « **Reply #6 on:** August 01, 2018, 12:25:51 am »

Those newer ones are nice, but the switches aren't as massive as the old ones. AFAIK, they never made a 7 decade unit in the old style. I just use a couple 1432 series, with the range suited to the purpose at hand. Don't forget the less pretty Shallcross resistance boxes. IMO, probably as good as the GR, and a handier footprint on the bench. An interesting GR one is the 670-F compensated box for AC use. Introduced in the March 1934 issue of the Experimenter, it also switches small inductors to keep a constant inductance value for every setting. At the very end they show a compensated slide wire that's pretty clever.

https://www.ietlabs.com/pdf/GR_Experimenters/1965/GenRad_Experimenter_Oct_1965.pdf
https://www.ietlabs.com/pdf/GR_Experimenters/1934/GenRad_Experimenter_March_1934.pdf

branadic · « **Reply #7 on:** August 03, 2018, 10:32:48 pm »

Measured decade resistor box on 3458A today and it seems to be well within spec. So if one of you is searching for a working unit, there are still two units left.

-branadic-

Conrad Hoffman · « **Reply #8 on:** August 03, 2018, 11:11:09 pm »

FWIW, I've never seen a GR resistance box out of spec. Even some mildly toasted units (discolored from overload) have measured OK. I've got quite a few old ones, but none of the newer horizontal style due to the price premium they seem to carry.

mmagin · « **Reply #9 on:** August 03, 2018, 11:47:05 pm »

I've got one of the old black finish 5 decade GR 1432 boxes. Aside from needing some cleaning, it's worked just as spec.

BradC · « **Reply #10 on:** August 04, 2018, 08:35:17 am »

Quote from: branadic on August 03, 2018, 10:32:48 pm

Measured decade resistor box on 3458A today and it seems to be well within spec. So if one of you is searching for a working unit, there are still two units left.

...One unit left.

Dwaine · « **Reply #11 on:** August 14, 2018, 04:07:53 pm »

I bought one too. Really good condition.

BradC · « **Reply #12 on:** August 15, 2018, 07:08:27 am »

Quote from: BradC on August 04, 2018, 08:35:17 am

...One unit left.

Arrived yesterday. Meets specification within my limited ability to test directly.
Hooked it up today as the variable trimming element in a Wheatstone bridge. What a pleasure to use.

branadic · « **Reply #13 on:** August 15, 2018, 06:02:01 pm »

Nice, 3 out of 4 are in this community

-branadic-

DC1MC · « **Reply #14 on:** August 15, 2018, 07:58:48 pm »

Is there any left ?

DC1MC

doktor pyta · « **Reply #15 on:** August 16, 2018, 09:42:13 am »

You may consider this (from DE):
https://www.ebay.de/itm/Doppelte-Tettex-Widerstandsdekade-Messgerat-Resistance-Decade-Typ-1122/401570133849?hash=item5d7f71f759:g:xMwAAOSw9fpbUbOy
Tettex is also known for it's quality products.

branadic · « **Reply #16 on:** August 16, 2018, 01:34:24 pm »

Quote from: DC1MC on August 15, 2018, 07:58:48 pm

Is there any left ?

DC1MC

Quote

Pictures and datasheet of a General Radio Type 1434-G - Decade Resistors can be found on internet, but what is such a unit worth and what to look after?

Simply click the link

-branadic-

cat87 · « **Reply #17 on:** August 17, 2018, 03:25:37 pm »

Quote

Nice, 3 out of 4 are in this community

Make that 4 out of 4

Will do the mandatory posting of measurements when i get it. September-ish, if I'm to believe eBay's estimation

cat87 · « **Reply #18 on:** August 29, 2018, 03:21:14 pm »

Well well, guess Christmas sometimes does come early. The GenRad decade resistor just arrived today. Checked all the decades and with my 3478A, all I can tell is that the unit is well within spec. The higher ranges approach 0.02% but the lower ones are around 0.015%

All in all, not bad. I have a Keithley 199 that's I might calibrate with the GenRad and a Fluke 8505A that's way out of whack on the Ohms ranges. Might give that a try also. It'll be some fun couple of days


EEVblog Main Site	EEVblog on Youtube	EEVblog on Twitter	EEVblog on Facebook	EEVblog on Odysee

Author Topic: Suggestion on decade resistor? (Read 4056 times)

Share me