[Elecraft] Dummy load

[Bob McGraw K4TAX]

Those gallon bucket dummy loads, often referred to as "Cantenna" loads, 
are inexpensive and generally work OK to a limit.  They do have specific 
power limitations vs. time such as 1 minute at 1KW.   Also, they may not 
be 50 ohms.   Yes, the label says 50 ohms, but is it?   All 3 of mine 
measure differently.  One as high as 68 ohms.   And they change 
impedance as they heat.   I've purchased all of mine new and two are now 
quite old.  The 3rd one is 3 years old and has migrated up a few 
ohms.    Beware of hamfest bargains unless you know what you are buying.

On the other hand and for many more $$$$, the loads made by Bird and 
Celwave and other commercial loads are more reliable and accurate.  They 
also cost a lot more money.   And even with these, beware of hamfest 
bargains unless you know what you are buying.

Here is a link to the company I've dealt with for Bird products. 
https://www.nm3e.com/loadSampler.htm#LoadSampler

Accurate and known value loads are necessary when measuring power.   
Most power meters and measurements are accurate at 50 ohms.  Use a 
different impedance load or one that has changed value and the power 
meter will become one of questionable accuracy.

73

Bob, K4TAX


On 5/1/2019 7:40 AM, Mark Goldberg wrote:
> How much do you want to spend?
>
> One of these Bird Termaline series, or similar is the top of the line, but
> will cost you:
>
> https://www.birdrf.com/Products/Test%20and%20Measurement/Loads/Coaxial-Terminations/500-watts/8201_500-Watt-Oil-Cooled-Terminations.aspx
>
> I was lucky to find a DA412B/U military surplus 600W dummy (similar to Bird
> 8401) load at a hamfest for cheap.The good ones have N or better connectors
> and Hams tend to avoid them. Adapters are not expensive if you want to
> connect to PL259s, but I actually use Ns in most of my station. It will
> take a continuous key down from my KPA500 with no problem.
>
> 73,
>
> Mark
>
>
> On Wed, May 1, 2019 at 5:04 AM richard gilley <richgilley123 at gmail.com>
> wrote:
>
>> Hi,
>> Would like a recommendation for a 500 watt dummy load.
>>
>> Thank you all
>> Richard  AD1G
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