[Elecraft] Re: QRP Dummy Load

[Don Wilhelm]

Tom and Ron,

My two cents - a known accurate dummy load is important to me.  Most of the
time 20% off is OK because I am just using it as a loading device.

HOWEVER, when I want to make measurements, it must be accurate, and I really
want it to be 50 ohms rather than 51 ohms. (Don Brown take note please).
The math to calculate power, etc. is much simpler when the resistance is 50
ohms, and IS the stated design point for most equipment.

73,
Don W3FPR
----- Original Message -----
|
| >One question I don't see answered here is, "How accurate do we need a
dummy
| >load to be?" It's a different world not that out rigs are "pre-tuned" and
| >expect a certain non-reactive impedance at the antenna terminal.
| >
| >Since so many people use commercial dummy loads without a problem, I'd
guess
| >the current crop of dummy loads is just fine. They seem to be accurate to
| >within only about 20% or so! They claim an SWR of only 1.3:1 or so.
| >
| >Is that adequate?
|
| A question I've been considering as well.
|
| Since many builders will be using their dummyload for both SWR and Power
| calibrations, I'd think we'd like to have RF resistance accuracy as good
as
| possible, GIVEN reasonable pricing. And, we'd certainly want to reduce
| residual reactance as much as possible.
|