[Elecraft] Dumb(?) dummy load question

[Bob Nielsen]

On Tue, Jun 22, 2004 at 09:32:30AM -0400, Eric Ward wrote:
> In an attempt to save pennies, I got a 10W 50 ohm resistor ($1.79 for two) at the Shack and soldered it to a male BNC--I figured this would make a serviceable QRP dummy load.  The resistor checked out at 50.0 ohm on my DMM.
> 
> When I hooked this to my KX1 and went through the ATU alignment procedure (nulling C9, etc), I only get an apparent out put of about 0.3W (according to the display on the radio).  Ditto when I tune my G5RV--I get to 1:1.1, but with only 0.3W.  (This antenna/feedline system is tunable by my LDG Z100 to 1:1; see below.)
> 
> I had previously gone through the ATU alignment using, instead of a dummy load, the G5RV routed through the external match (the LDG Z100) tuned for that frequency.  I figured that would  be pretty close to 50 ohm, since it achieves an apparent 1:1 on that freq with my Icom 706 rig.
> 
> When I use the tuned G5RV as a "dummy load" and go through alignment, I get what appear to me more reasonable values--i.e. when I subsequently tune the same antenna with the KX1 ATU, I get 4.3W and SWR of 1:1.6.
> 
> So something funky is going on and I cannot figure it out.  Is there some bloody obvious reason why the 10W resistor is not a good dummy load?  Is something else wrong with my rig, which otherwise is nominal in all respects?  (BTW, I have R4 maxed out clockwise.)  I do not have a wattmeter, so I cannot independently check output with and without the ATU installed, but the rig is transmitting on 40 and 20m.
> 
> Thanks for any ideas...

Is it a non-inductive resistor?  If not, it probably won't be anywhere
near 50 ohms at R.F.

Bob, N7XY