[Amps] wirewound resistor inductance/capacitance parameters

[Carl]

----- Original Message ----- 
From: "David Kirkby" <david.kirkby at onetel.net>
To: "Carl" <km1h at jeremy.mv.com>
Cc: <pc5m at xs4all.nl>; <Amps at contesting.com>
Sent: Monday, April 18, 2011 5:01 PM
Subject: Re: [Amps] wirewound resistor inductance/capacitance parameters


> On 18 April 2011 18:36, Carl <km1h at jeremy.mv.com> wrote:
>> For 160 you can probably do that with a couple of warehouse/stadium 
>> wattage
>> lightbulbs. Measure the reactance and add the opposite sign to cancel.
>>
>> Carl
>> KM1H
>>
>
> Wirewound resistors are not perfect, but at least they will be stable
> with temperature and power applied. The same can not be said for light
> bulbs.
>
> At 2.0 MHz, wire-would resistors might well be OK. But if they are not
> good enough, tweaking them with some external reactance will be a lot
> easier than trying to tweak something that will have massive change in
> parameters depending on the applied power.
>
> Dave

Fortunately for the hobby and industry, light bulbs were the norm for 
decades; this included broadcast transmitters.

We now have SWR instruments to help determine the viability of a light bulb 
load as well as the ability to make changes as needed. QST ran an evaluation 
a long time ago and it was either the 60 or 100W bulb that offers a good 
load for a 50-75 Ohm TX.

A little bit of experimenting with series parallel configurations may prove 
rewarding.

Carl
KM1H