[NJARC] resistors

[E. Suhaka]

Here is a link that can explain a little more about resistor values and 
tolerances.

http://www.logwell.com/tech/components/resistor_values.html

Ed
N2COV



On 5/21/2013 5:34 PM, Harry Klancer wrote:
> Just remember
> Reply = Poster
> Reply All = Everyone
>
> _________________________________________________________
> Victor,
>
> Depends on the type of resistor and where it's used.
>
> Carbon comp. resistors generally came in 3 tolerance ranges.
> 20 percent (no tolerance marking),
> 10 percent(silver band)
> and 5 percent (gold band).
> If the manufacturer designed acircuit and used a 20 percent
> resistor in a certain spot, thatmeans he believed the circuit
> would work with a 20 percentresistor. 10 percent resistors
> are a little better, and lots of them were used too.
>
> As an example, a 180K 20 percent resistor might have a
> value anywhere between 144K (180K - 20 percent of 180)
> and 216K (180K + 20 percent of 180). When the radio was
> built, think of it as if somebody reached into a bucket of
> 20 percent resistorsand what he pulled out and put in
> the radio might have been anywhere betweenapproximately
> 140K and 220K.
> Reaching in a bucket of10 percenters, he would have
> got a resistor between approximately 160Kand 200K.
> Better, but still not a very tight tolerance.
>
> So if YOU put in a 220K resistor (as measured on your
> digital ohmmeter), just remember that the original
> might have been almost as high as 220K and the radio
> still worked.(or the original might have been as low
> as 140K, so you couldeven put in a 150K)
>
> That's also why resistors come in RETMA standard
> values, say 150K, 180K, 220K, 270K, and so on.
> The 180 covers the range between the 150 and 220,
> the 220 covers the range between the 180 and the 270,
> and so on. Early radios with dogbone resistors tended
> to have values suchas 100K, 200K, and so on. Don't
> worry, just replace these with a close RETMA value.
>
> HOWEVER, if the manufacturer used
> a 5 percent resistor (which cost him more) or even
> a special (and very expensive) resistor marked 1 percent,
> that meansthe actual value was more important. In the case
> we looked at above, a 5 percenter would be
> between 170K and 190K. He spent the extra money
> because he thought it was important. You should too.
>
> Somebody else can talk about wirewound resistors.
>
> Harry K
>
>
> On 05/21/2013 2:16 PM, VICTOR BELLINI wrote:
>> Just remember
>> Reply = Poster
>> Reply All = Everyone
>>
>> _________________________________________________________
>> question....when replacing resistors in tube radios how important is
>> to replace with the exact ohms....can you replace with slightly higher
>> value.....I know that the watts rating is important as it affects
>> voltage but won't hurt to replace 1/2 watt with 1 watt but I am not
>> sure regarding the ohms.....thanks
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