[ARC5] Resistor Excursions

[Bob kb8tq]

Hi

If you measure them correctly, they do exhibit the “stays resistive” characteristic up at least into the VHF region. There are papers on this going back into at least the 1930’s. Yes, your test setup has to be pretty carefully done to take out any incidental stray C …. Last time I did that sort of testing was in the 1970’s. 

Bob

> On Apr 19, 2024, at 7:35 PM, Richard Knoppow <1oldlens1 at ix.netcom.com> wrote:
> 
>   What is the source of your information?  I have measured many CC resistors using a Boonton RX-Meter and found they become more reactive at RF. While many think film resistors become inductive I have not found that true. Curiously enough the examples in the Boonton handbook show the same thing.
>   I was taught the same thing about CC resistors but it seems not to be true.
> 
> On 4/19/2024 4:23 PM, Bob kb8tq wrote:
>> Hi
>> If you *do* decide to replace CC’s with a different type of resistors, do a deep dive into just how weird CC’s are at RF. Unlike pretty much all other resistors, they drop value, but stay resistive as frequency goes up. While that sounds a lot like a resistor model that includes a cap, it’s not. The phase shift with “pure resistive” is not the same ….
>> How much does this matter? It very much depends on how tricky the circuit happens to be. In many cases … not a big deal.
>> Bob
> 
> -- 
> Richard Knoppow
> Los Angeles
> WB6KBL
> SKCC 19998