Assistance in Identifying an old part - CTC-1357A

Thread Starter

Sky779

Joined Jan 12, 2016
7
I've got an old part here i'm hoping to find some assistance in identifying. Google comes up with nothing for the markings on the case. CTC-1357A

It looks like a cross between an old high voltage Mega Ohm resistor and a dual package axial capacitor.
20161219_092420.jpg 20161219_093405.jpg 20161219_095244.jpg
On the left side one lead is marked in and the other is marked out the right single lead is marked GND.
Resistance between the in and out legs is about 320 Ohms and is an open circuit between either leg and the ground.
20161219_092537.jpg 20161219_093915.jpg 20161219_093929.jpg 20161219_094020.jpg

Thanks in advance
 

ian field

Joined Oct 27, 2012
6,536
I've got an old part here i'm hoping to find some assistance in identifying. Google comes up with nothing for the markings on the case. CTC-1357A

It looks like a cross between an old high voltage Mega Ohm resistor and a dual package axial capacitor.
View attachment 117160 View attachment 117161 View attachment 117170
On the left side one lead is marked in and the other is marked out the right single lead is marked GND.
Resistance between the in and out legs is about 320 Ohms and is an open circuit between either leg and the ground.
View attachment 117162 View attachment 117167 View attachment 117168 View attachment 117169

Thanks in advance
The packaging reminds me of selenium EHT stacks - but I can't think of any with 2 wires at one end.

A GND terminal could be for an internal reservoir capacitor.
 

recklessrog

Joined May 23, 2013
985
Could it be a screened wire wound resistor?? is the ground lead connected to the two end caps? is there continuity between the end caps?
 

musiklab

Joined Jul 20, 2014
5
it would help to know where it came from, if in a circuit .
try heating it with a lighter flame, or hair dryer- while monitoring the resistance.
could be a thermistor
ptc if heat increases the resistance significantly, going from cold to hot , NTC if reducing it.
 

ian field

Joined Oct 27, 2012
6,536
it would help to know where it came from, if in a circuit .
try heating it with a lighter flame, or hair dryer- while monitoring the resistance.
could be a thermistor
ptc if heat increases the resistance significantly, going from cold to hot , NTC if reducing it.
If its what Dodgydave said; it'll just be the tempco of a long length of copper wire. A luma delay is usually a single layer solenoid wound coil wound over a strip of foil for distributed capacitance.

Heating it will probably scorch the casing before you get enough heat into it for a measurable change.
 

Thread Starter

Sky779

Joined Jan 12, 2016
7
Well I'll be... because of what Dodgydave said I hooked it up to a Function generator and an O-scope and when i peg out the freq. on the function generator it offsets a sine wave by an entire 1/2 period.

I'm a student worker for the Electronics Shop that supports the Chemistry and Physics departments at a University. We support both the teaching labs and the research labs. Most of the equipment that the shop sees is either brand new or quite a few decades old. So seeing the dates of 20's to 40's in the wiki doesn't surprise me in the least. The shop manager handed one to me and told me to figure out what it was so we could decide to keep the drawer full or surplus them.

@recklessrog - the case and endcaps are isolated from the wires and each other.

@musiklab - Because of the nature of the shop there is no telling where they came from or what their original purpose was for. We found a drawer full of new unused pieces back in the back of the shop. The shop is 23.3C and the unit read a resistance of 317 ohms. using a heat gun I raised the temp of the unit to 47C and the resistance raised to 350 ohms. Now about 5 min later the unit is still at (in places) a max of 38C and the resistance is 337 ohms. So no significant resistance change.
 
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