Resistrors - Electrosil TR4/TR5/TR6

[awood]

Hello! Firstly, I'm new to the site, been browsing a few weeks and picked up plenty. However, now need to put it to good use!

Currently working in an aerospace department in the U.K. where we focus mainly on electronnic/electrical engineering. I'm conducting an obsolescence review of one of our old (c. 20 yrs) products.

Being as none of the current staff were here when the product was designed originally, we have limited knowledge! The majority, 80% I'd say, of the resistors called up on the parts lists are either TR4, TR5 or TR6 part numbers. As I understand it, these are an Electrosil part, who were subsequently taken over by Corning, who then became Dow Corning, who now have no reference to these parts whatsoever. They are 'glass tin oxide' resistors, a type of resistor I have yet to encounter thus far in my very young career!

I obviously need a suitable alternative, and would imagine they can be replaced by your average carbon film/metal film resistors; provided power and tolerance specifications are matched.

Out of curiosity, if anyone has information on these resistors, it would be interesting to read! Any special considerations I might make?

Thanks in advance!!

 

[Skogsgurra]

Welcome! You are right! This is a great place. It is like having hundreds of specialists available 7/7 24/24 and you do not even have to leave your office chair to contact them. We all get great education by participating.

The old Electrosil specialised in UHF and VHF resistors. There is a description here

http://www.g3ynh.info/zdocs/comps/part_3.html

scroll down about 60 - 70 % to read about a dummy load made by Electrosil.

The whole article is worth reading.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[itsmoked]

You must exercise some care in that assumption awood.

Older resistors were often made resistive by 'bulk' methods that included the composition of the material they were made of. Newer resistors are more commonly made by the length of the material structure. Longer of course equals more resistance.

How is the length made longer in a short device? Wrapping! Wrapping means coils. Coils mean inductance.

I've designed through this industry change. I have seen many products fail to operate properly because of a switch to modern resistors from earlier versions.

If your circuitry runs at higher frequencies you need to analyze the inductive differences of the original with any new replacement candidates.

Keith Cress
kcress -

http://www.flaminsystems.com