[Elecraft] Re: QRP Dummy Load

[Ron D'Eau Claire]

I had good results with that design when I first saw it in the 1960's. =
Only
in those pre-pcb days, for loads bigger than pennies could handle we =
used
half-dollars (they were not only common, but US coins had real silver in
them back then!) or pieces of copper "flashing" from the hardware store. =
=20

Now that worked GREAT for hollow-state (tube) equipment with pi-net =
outputs
and simple solid-state gear also with tunable outputs in which we only
wanted something "in the ballpark". We didn't care too much what the =
REAL RF
resistance was as long as it was sort of 50 ohm-ish and sort of
low-reactance.=20

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.=20

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?=20

Ron AC7AC
K2 # 1289

-----Original Message-----
Another possibility is a project that was published in the NJ-QRP's QRP
Homebrewer (Issue #2).

The "Common Cents" QRP Dummy Load, by Dave Ottenberg, WA2DJN... is no
ordinary dummy load, as it's made by sandwiching four carbon resistors
between two pennies, soldered right on top your favorite antenna =
connector.
=A0 So all you need to do is connect this little 1" dummy load connector =
to
your rig ad your as safe as
can be.

Instead of four 200-ohm resistors, I used six 300-ohm resistors at 2W =
each
to approach full power for my barefoot K2. And instead of pennies, I =
used
little discs of double-sided PCB material. ...

Pictures at: http://www.njqrp.org/qhbextra/2/2i.html

72,
David, AD2A
Glen Rock, NJ
K2 #265