Inductance of 820 ohm 10w wirewound

Can anybody with a good inductance meter, please measure a 10 watt
wirewound resistor of 820oms and tell me the inductance. I am getting
wildly different figures from various sources.

Thanks all.

"StrandElectric"<Strand_at_dummyspit> wrote in message
news:4e004ab0$1_at_dnews.tpgi.com.au...
Can anybody with a good inductance meter, please measure a 10 watt
wirewound resistor of 820oms and tell me the inductance. I am getting
wildly different figures from various sources.

Thanks all.



Probably quite manufacturer dependent???


Yes , depends on turns and type/length of wire included

Can anybody with a good inductance meter, please measure a 10 watt
wirewound resistor of 820ohms and tell me the inductance.

"StrandElectric"

Can anybody with a good inductance meter, please measure a 10 watt
wirewound resistor of 820ohms and tell me the inductance.


** The inductance is so small it is totally irrelevant compared to the 820
ohms of resistance.



.... Phil

Phil. That depends entirely on the frequency in use, in this case up to 30

Can anybody with a good inductance meter, please measure a 10 watt
wirewound resistor of 820oms and tell me the inductance. I am
getting wildly different figures from various sources.

"Phil Allison" "StrandElectric"

Can anybody with a good inductance meter, please measure a 10 watt
wirewound resistor of 820ohms and tell me the inductance.

** The inductance is so small it is totally irrelevant compared to the
820 ohms of resistance.


Phil. That depends entirely on the frequency in use, in this case up to 30
Megs!

I still neeed that measurement.

StrandElectric wrote:

Can anybody with a good inductance meter, please measure a 10 watt
wirewound resistor of 820oms and tell me the inductance. I am
getting wildly different figures from various sources.

**That's because there is no one, correct answer. Some wirewound resistors
are bifilar wound,

You need specify which resistor you are using.

Better still, you should contact the manufacturer, as he/she will be able
to provide all the data you require.

Even betterer, would be for you to measure the inductive reactance of the
resistor,

Can anybody with a good inductance meter, please measure a 10 watt
wirewound resistor of 820oms and tell me the inductance. I am getting
wildly different figures from various sources.

Thanks all.
*if* it's a straight coil of wire with an air core, then Wheelers formula

"StrandElectric"
"Phil Allison" "StrandElectric"

Can anybody with a good inductance meter, please measure a 10 watt
wirewound resistor of 820ohms and tell me the inductance.

** The inductance is so small it is totally irrelevant compared to the
820 ohms of resistance.


Phil. That depends entirely on the frequency in use, in this case up to
30 Megs!


** The change in impedance is not going to be more than 2 ohms - and might
be up or down.

I still neeed that measurement.

** Try using this.

http://www.daycounter.com/Calculators/Air-Core-Inductor-Calculator.phtml

You should get about 0.3 uH

At 30 MHz, this has a Z of 56 ohms

The new impedance of your 820 ohm resistor is then 822 ohms - in theory.

You are wasting your time.


..... Phil

That's a bit hasty Phil, as you don't know what I'm trying to do and what

StrandElectric wrote:
Can anybody with a good inductance meter, please measure a 10 watt
wirewound resistor of 820oms and tell me the inductance. I am
getting wildly different figures from various sources.

**That's because there is no one, correct answer. Some wirewound resistors
are bifilar wound, which exhibits far lower inductance figures than
regular wound resistors. You need specify which resistor you are using.
Better still, you should contact the manufacturer, as he/she will be able
to provide all the data you require. Even betterer, would be for you to
measure the inductive reactance of the resistor, as this data is likely to
be far more useful to you.


--
Trevor Wilson
www.rageaudio.com.au
Agreed Trevor, but my crude instrument is very poor at measuring L. I was

"Trevor Wilson"
StrandElectric wrote:

Can anybody with a good inductance meter, please measure a 10 watt
wirewound resistor of 820oms and tell me the inductance. I am
getting wildly different figures from various sources.

**That's because there is no one, correct answer. Some wirewound
resistors are bifilar wound,

** Invariably labelled "non inductive" and cost way more.

You need specify which resistor you are using.

** 10W, WW = standard rectangular cement coated resistor.

Better still, you should contact the manufacturer, as he/she will be able
to provide all the data you require.

** If you speak Chinese.

Even betterer, would be for you to measure the inductive reactance of the
resistor,

** OK - you go get a 10W, 820 or 1000ohm cement resistor and YOU measure
its inductance.

Go on - try !!


.... Phil

Agreed Phil!

"Phil Allison"

Can anybody with a good inductance meter, please measure a 10 watt
wirewound resistor of 820ohms and tell me the inductance.

** The inductance is so small it is totally irrelevant compared to the
820 ohms of resistance.


Phil. That depends entirely on the frequency in use, in this case up to
30 Megs!


** The change in impedance is not going to be more than 2 ohms - and
might be up or down.

I still neeed that measurement.

** Try using this.

http://www.daycounter.com/Calculators/Air-Core-Inductor-Calculator.phtml

You should get about 0.3 uH

At 30 MHz, this has a Z of 56 ohms

The new impedance of your 820 ohm resistor is then 822 ohms - in theory.

You are wasting your time.


That's a bit hasty Phil,

as you don't know what I'm trying to do

Agreed Trevor, but my crude instrument is very poor at measuring L. I was
hoping that someone who uses Jaycar 10% R would also have a decent
measuring instrument.