Decade Boxes- All types

FrankB wrote:

GR products are great, but the average experimenter can't afford them..

I have on occasion seen them reasonably priced at hamfests and antique radio meets. The cost is not an obstacle to me, though, as I sometimes use them professionally.

Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA
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Here some more brands:

Biddle Gray
Heathkit
I.E.T.
EICO
Global Specialities
Leeds & Northrup
Clarostat
Welch
Yokogawa
ESI Dekabox

There are kits-rotary dial, switch type, plugin jumpers

If you want to see choices here's a link


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GR products are great, but the average experimenter can't afford them.
 As to tolerances, I think generally 5% is OK, but tighter tolerances are better for finding meter shunts and such. It really depends on what you are wanting to do with the box when you get it built. Many resistors at 2% tol. are the same price as 5% ones. Your choice. Just remember to test everything before assy.

 I made one with various resistors ( 2 W) in series, with banana jacks between each resistor. I calibrated the meter so I could use it to test the voltages on the big industrial vinyl welders I used to service. IIRC, 2KV, 5KV & 10KV. My Pomona & B&K HV probes were too hard to read accurately at those voltages accurately

Wire wound power resistors will likely be 5, 10 or 20% at best.  Depends on who make them. I try to stay with no more than 5% on power resistors also.

( I should add that if you can get your hands on early  B&W TV tuners, many of them use 12 position rotary switches that could be salvaged out for decade boxes).

All of my decade boxes have survived very nicely, but they are all GR.

Dale H. Cook, Retired Chief Engineer, Roanoke/Lynchburg, VA

I've often thought about building both a capacitor one as well as a resistor one. What are your thoughts as to the tolerances of the parts? Use only precision or will standard +/- 20% ones be suitable? 

I kinda prefer precision myself, but if standard tolerance ones are OK, it would no doubt be the cheaper way I would think.

If you find an old decade/ sub. box, first thing I recommend is to open it up. To a quick eyeball and test all the parts.
 It does not matter what type of decade box it is, TEST THE PARTS BEFORE USING.

As a rule, the switches may need a bit of lube and cleaning, but typically are not bad, unless someone really dumped a lot of HV or current into them.

I have seen a couple of the boxes where there were many burned up parts inside.
 Be sure to check the test leads if they are not removable. Much of the old wire insulation has deteriorated over the many years. Cracked, fallen off, broken wires, etc. I just replace the leads and in most cases, will add banana jacks instead of attached wires. Makes for easier storage, and less test lead "rat nests". 9Also sometimes you need longer leads, or different connectors on the other end. Banana jacks make it easy to chose what you need.

 You will find a large number of resistors have changed value,, and generally all caps have gone bad, no matter if they are fixed,  electrolytic, or mica, and diode sub boxes also need to be tested. Yes, they even made transistor sub. boxes too!

It will also let you know the wattage of the resistors inside, and if one had been previously damaged, was it replaced with the correct value/wattage? 
 When I rebuild resistor decade boxes, they generally came with 1/2 watt resistors. I suggest replacing them with the 2% flame retardant types in 2 watt. It may save you from future problems, and be sure to put a sticker on the box stating you have upgraded the wattage. I have seen 1/2 watt resistors replaced by higher and lower wattage resistors when a tech fried the original resistor.

They also made power resistor sub. boxes using wire wound resistors. A check of the value, looking for any damage, etc. is good, and note the wattage of each resistor value. I have seen some boxes where they used 1 & 2 watt resistors and then 5 and 10 watt resistors in the same box 
  Be sure to mark the wattage of the resistor on a tag on the box, if it is not labelled.

A quick spray of contact cleaner & lube and you will have a piece of equipment that will last you for years with a bit of care.

One type of odd ball box had selenium rectifiers in them, of varying current and voltage values also, and I remember seeing a sub box using fused resistors in different values. (For use on early TV sets, no doubt).

It is really easy to make your own boxes too. They make up to 23 position rotary switches, ( That I have seen and used), non shorting, and all you need to do is add a box, components knob, and labels for the values. No hard and fast rule on how many positions you need, use what you have or can easily obtain. Just be sure to stay within the current the switch contacts will handle safely.

If you make an electrolytic sub box, it might be handy to add a bleeder resistor switch to the box to discharge the capacitors too.