Resistor just out of tolerance - UK Vintage Radio Repair and Restoration Discussion Forum

BigClick · 31st Dec 2015, 11:12 am

Hi,

I have a SG (screen grid?) stopper resistor that measures 43.1ohm. The trader sheet specifies 39ohm and it has a silver band (10%?).

I calculate that this resistor is 0.2 ohms too high. Not much but it is over.

Would this be considered ok to use in general or is each case specific and if it is specific am I ok with this one?

thanks

Station X · 31st Dec 2015, 11:13 am

It will be fine.

Brian R Pateman · 31st Dec 2015, 11:19 am

What did you measure it with?
Did you take account of lead resistance?

Your measurement errors are likely to exceed the tolerance error of the component.

As Graham says, it will be fine.

broadgage · 31st Dec 2015, 11:21 am

Agree that it will be fine. And it might be just within tolerance anyway, the small difference that you have observed is well within the expected instrument error, unless you are using something of unlikely accuracy.
0.2 of an ohm could even be variations in contact resistance depending on how firmly the test leads were connected to the component under test.

G8HQP Dave · 31st Dec 2015, 11:47 am

Stopper resistor values are rarely critical. You could probably use a 33 or 47 without any problems.

paulsherwin · 31st Dec 2015, 12:12 pm

Resistor values are rarely critical in valve domestic radios. I only change them if they are massively out or if a related fault is present.

Radio Wrangler · 31st Dec 2015, 5:57 pm

Expect 10% resistors to be near the edges of the tolerance band. Those closer to the middle used to get flogged as 5% parts. So a plot of population versus resistance would look "M"-shaped with two peaks and a dip in the middle.

David

31st Dec 2015, 11:12 am	#1
BigClick Hexode Join Date: Dec 2015 Location: Walsall, West Midlands, UK. Posts: 327	Resistor just out of tolerance Hi, I have a SG (screen grid?) stopper resistor that measures 43.1ohm. The trader sheet specifies 39ohm and it has a silver band (10%?). I calculate that this resistor is 0.2 ohms too high. Not much but it is over. Would this be considered ok to use in general or is each case specific and if it is specific am I ok with this one? thanks

31st Dec 2015, 11:13 am	#2
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Resistor just out of tolerance It will be fine. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

31st Dec 2015, 11:19 am	#3
Brian R Pateman Nonode Join Date: Jun 2005 Location: Western Lake District, Cumbria (CA20) - UK Posts: 2,136	Re: Resistor just out of tolerance What did you measure it with? Did you take account of lead resistance? Your measurement errors are likely to exceed the tolerance error of the component. As Graham says, it will be fine. __________________ Brian

31st Dec 2015, 11:21 am	#4
broadgage Nonode Join Date: Jan 2010 Location: North Somerset, UK. Posts: 2,130	Re: Resistor just out of tolerance Agree that it will be fine. And it might be just within tolerance anyway, the small difference that you have observed is well within the expected instrument error, unless you are using something of unlikely accuracy. 0.2 of an ohm could even be variations in contact resistance depending on how firmly the test leads were connected to the component under test.

31st Dec 2015, 11:47 am	#5
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: Resistor just out of tolerance Stopper resistor values are rarely critical. You could probably use a 33 or 47 without any problems.

31st Dec 2015, 12:12 pm	#6
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,970	Re: Resistor just out of tolerance Resistor values are rarely critical in valve domestic radios. I only change them if they are massively out or if a related fault is present.

31st Dec 2015, 5:57 pm	#7
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: Resistor just out of tolerance Expect 10% resistors to be near the edges of the tolerance band. Those closer to the middle used to get flogged as 5% parts. So a plot of population versus resistance would look "M"-shaped with two peaks and a dip in the middle. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done