Resistor Values and voltage rating

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Jhyatt2012
Posts: 46
Joined: Thu Mar 08, 2012 4:35 am
Location: East Texas

Resistor Values and voltage rating

Post by Jhyatt2012 »

I am putting together a parts list for the #183. I would like to use metal film resistors as much as possible if at all possible. I've noticed in lists for #124 and #102 the resistor values float from 1W for Carbon Films to 1/2W for Metal Films for the same resistor, depending on the list. Also, how critical are the voltage ratings? I am guessing that you at least want a 500v or better?
diagrammatiks
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Joined: Sun Mar 27, 2011 12:28 am

Re: Resistor Values and voltage rating

Post by diagrammatiks »

Jhyatt2012 wrote:I am putting together a parts list for the #183. I would like to use metal film resistors as much as possible if at all possible. I've noticed in lists for #124 and #102 the resistor values float from 1W for Carbon Films to 1/2W for Metal Films for the same resistor, depending on the list. Also, how critical are the voltage ratings? I am guessing that you at least want a 500v or better?
plate resistors, screen resistors, and power supply dropping resistors should be 500.
Jhyatt2012
Posts: 46
Joined: Thu Mar 08, 2012 4:35 am
Location: East Texas

Re: Resistor Values and voltage rating

Post by Jhyatt2012 »

Thanks - stupid question time...

Which are the screen resistors and which are the power supply dropping resistors? I'm not familiar with all of the terminology yet, but I'm learning. :)

Also, except for the power supply and where 2w or 5w are designated on the schematic, do I want to use 1w or can I use 1/2w?
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Structo
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Location: Oregon

Re: Resistor Values and voltage rating

Post by Structo »

I like to use 1 watt resistors throughout in the preamp.'
They are larger and easier to work with.

The screen resistors are on the power tubes, typically 470R for 6L6 and 1K for EL34.
They should be 3-5watts.

In the power supply the resistors between nodes are the dropping resistors.

They "drop" the voltage for the various stages.

They should be 3W metal oxide "flame proof" resistors.

A. Dumble liked the Vishay/ Dale RN65D metal film resistors on the preamp plates.
They are mil spec and spec at .6W but in reality they more like 1 W.
http://www.mouser.com/ProductDetail/Vis ... LvyFRuw%3d

For the interstage resistors carbon film can be used but it is sometimes difficult to acquire high quality ones, but Xicon is probably OK.

If you are entertaining the thought of building a Dumble, be advised it's a pretty advanced build for people even if they have a couple tube amps under their belt.

You need to do a lot of research here, because it's all here and in the file section. :D
Tom

Don't let that smoke out!
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