[bars] Carorundum what?

[Stephen Crook]

They are 100 ohm *non-inductive* power resistors  (as opposed to more common wire wound power resistors, which, due to being made by winding resistance wire, into a coil over a tube shaped ceramic form, are inductive as well as resistive. This doesn’t matter for DC, or even 60Hz AC, at that low frequency the inductive part is trivial but RF at say 1…, 10…, 100…, or more MHz, the inductance matters a lot!

Regarding ham applications: two in parallel would result in 2*190W=380W of power dissipation at 50 ohms resistance (so essentially 1.0:1 SWR) perfect for a dummy load to test or to tune-up ham radio transmitters and amplifiers. 

Carborundum is just silicon carbide… also used as an abrasive (e.g. black SiC “wet-or dry“ sandpaper). It is moderately conductive, so can be used for resistors, as in this case. 

        = Steve — KB1LKR =
Sent from my iPhone

> On Jul 5, 2023, at 8:28 PM, KC1SOZ <kc1soz at bd5.com> wrote:
> 
> 
> Anybody know what this is used for in HAM radio?
> 
> https://nh.craigslist.org/ele/d/exeter-ham-radio/7639939794.html
> 
> 73,
> KC1SOZ
> Juan
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