[Elecraft] BNC 5W Dummy Load

[Fernando Quinones]

Vic Rosenthal wrote:

>
> A couple of questions and a comment:
>
> 1) The picture is captioned "5w BNC with ..."  Do you have an ethernet 
> terminator that is rated for 5w, or are you saying that it can handle 
> 5w when it's heatsinked by the oil.  I have a bunch of BNC ethernet 
> terminators, but they appear to be able to handle only a watt or less 
> in air.

No.. I meant to say 5W dummy load, your are correct about the less than 1W .

>
> 2) Is the purpose of the extensions to get the terminator into the 
> middle of the jar so it will be surrounded by oil, or is there another 
> reason?

Yes. like the Heath Cantenna

>
> 3) Comment:  I'm surprised that the thermal conductivity of the small 
> interface between the terminator and the oil is good enough to allow 
> you to use it with your Jupiter!


Clarification, I was using the tuning button of the Jupiter into the 
dummy load while setting the 4.mhz  osc and using
spectrogram as has been describe here before.. I usually have the 
Jupiter menu item show SWR as oppose to PWR.
Any hoot, tune only has 17W out according the the PWR graph on the 
Jupiter. And since I don't
look at this, I inadvertently assumed incorrectly, that I was QRO. 
Meaning 100w.
You see, I have only use my Jupiter with a SGC 239 tuner and don't use 
tune, just key the key.

Oh.. I had forgotten about the dummy load, I had overfilled it and it 
kept seeping out. My work
area is a small roller type tv dinner table, so as soon the 4mhz test 
was done, I put it under the
sink and forgot about it.

I then proceeded to do a kind of ugly test to see how much power the 
termination would handle.
Here are some picture of the setup. Elementary really. 
<http://pages.sbcglobal.net/nf6q/k2dummyloadtest.html>

Use my RF Analyst to see if there is 52 impedance at the start.
Remove the Analyst and put the Jupiter. Place Jupiter on tune, swr good 
on external one and PWR on rig showed 17W.
I then key the Jupiter, increasing the Power and watching the external 
SWR meter until the SWR started creeping up.
I see that Jupiter PWR indicates 25W.
I use the Analyst again to check the impedance an see that it has 
change, 36z..
So I interpret this to mean that the BNC termination has changed at this 
point and it could handle about 20W in oil.

Not scientific but it's what I can handle and understand.

>
> This is a great idea if it is really practical, because the 
> terminators are very good (low-reactance) dummy loads!  If I make one, 
> however, it will be in a metal can.


I would not bother, but if you could put one of those transistor heat 
sink on it and put it in oil , that would work to
some extent.

It was the only jar available, the others are plastic. Nice words though..

I appreciated your comments and question. Got me to do a elementary 
test, and practice my picture taking.
Got to luv these digital cameras. Hey, maybe if someone has a digital 
video camera, they can make
a short .mov file showing how they setup their filters, or spectrogram. 
or something,, Beats having to
describe it.

P.S. The Jupiter sit idle, use only for MARS. All the collins have dust 
covers. Go K2..

Pardon my wordiness. have a great day.

>
> Vic K2VCO
>
>

-- 

73's Fernando NF6Q/NNN0JYM
San Jose,CA. 95123
Elecraft K2 #2330;KBT2
CCA #01187 FISTS #8649 FP#-622 
<http://pages.sbcglobal.net/nf6q>