Welcome to Australia's only Vintage Radio and Television discussion forums. You are not logged in. Please log in below, apply for an account or retrieve your password.
Australian Vintage Radio Forums
  Home  ·  About Us  ·  Discussion Forums  ·  Glossary  ·  Outside Links  ·  Policies  ·  Services Directory  ·  Safety Warnings  ·  Tutorials

General Discussion

Forum home - Go back to General discussion

 RESISTOR Sizes fo Classic 5 Valve
« Back · 1 · Next »
 Return to top of page · Post #: 1 · Written at 10:29:01 PM on 19 January 2014.
AndyRBin's Gravatar
 Location: Chuwar, QLD
 Member since 12 August 2013
 Member #: 1395
 Postcount: 29

Can somebody please help by giving me the correct resistor sizes.I have a diagram drawn by AORSM and the resistors are identified on the diagram by numbers and decimal points.
The resistors I want identified are - .04, .044, .05, .25 and .5
Momochrome did post some info but I am still confused.

From monochrome I did learn that numbers with no decimal points are in Ohms so 245 would be 245 Ohms.
Than 2 followed by a decimal point (2.) would be in Kilo Ohms. So this would be a resistor 2K.
After this I became lost.

GTC on my original post I have supplied some voltage readings. I have a feeling that nobody can see my last post.


 
 Return to top of page · Post #: 2 · Written at 11:47:14 PM on 19 January 2014.
Art's Gravatar
 Art
 Location: Somewhere, USA
 Member since 22 October 2013
 Member #: 1437
 Postcount: 896

That's odd, but couldn't you measure a few of them physically to find if there is a uniform method on the schematic?

If they were all written in Kilo, then the list you gave would read:
40R,44R,50R,250R, and 500R.
If they were all written in Megs, it would be:
40K,44K,50K,250K, and 500K.
They look like odd values for resistors though.


 
 Return to top of page · Post #: 3 · Written at 12:58:19 AM on 20 January 2014.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5254

I think your cause might be better served by pointing us to the actual circuit.

In many early circuits there were traps before RMA codes turned up. Some early ones had "M" after the value of all resistors in thousands. "M" in Roman numerals is 1000.

In many Australian circuits Ohms were ohms up to often 1000 perhaps more for a field coil. Then they sometimes resorted to "K" for 1000's: And Meg if it was. Just to annoy people they frequently jumped to decimal points of a Megohm and left off the leading zero, so the decimal point looked like fly dung.

Most of those 5 Valve sets followed a similar plot. look at the grid leak on the OP tube. 90+% of the time it is 500K and the plate resistor/s of the Det Audio Plate around 200K.

Grid R if it is 500K will be .5 and a 200K, 0.2 if they are in Meg. RMA code is what they used then, not what we have now. 500K use 470K. It will not be setting the bias.

With a bit more practice you will be able to predict what goes where . Generalising: The lowest resistances are generally in the PSU when "Backbiased" or, in the Cathode circuits. The highest R in AGC rails around the det audio.


 
 Return to top of page · Post #: 4 · Written at 11:28:07 AM on 20 January 2014.
AndyRBin's Gravatar
 Location: Chuwar, QLD
 Member since 12 August 2013
 Member #: 1395
 Postcount: 29

Marcc can you check the following for me please.

2. is 2K
1. is 1K
.5 is 500K
.4 is 400K
.25 is 250K

I am lost for .05 and .044

Regards
Andy


 
 Return to top of page · Post #: 5 · Written at 4:12:20 PM on 20 January 2014.
MonochromeTV's avatar
 Location: Melbourne, VIC
 Member since 20 September 2011
 Member #: 1009
 Postcount: 1182

I know the question was aimed at Marcc, but I can answer it for you.

The first 2 should be 2M & 1M.

If the resistor codes are the body end dot types the original 2M will have a red body, a black end and a green band around the body. The 1M will have a brown body, a black end and a green band around the body.

3, 4 & 5 are correct.

.05 is 50K (green, black & orange band) & .044 is 44K (all yellow with a orange band)

Any resistor between 1K & 9K will be shown as is. 10K is shown as .01

Maybe the old body end dot resistor code and the old fashioned way of showing resistor values has been the cause of confusion.

That said, I think some of the circuits drawn up by the AORSM are riddled with mistakes.


 
« Back · 1 · Next »
 You need to be a member to post comments on this forum.

Sign In

Username:
Password:
 Keep me logged in.
Do not tick box on a computer with public access.