[Elecraft] Product Suggestion - 500W Dummy Load

[Edward R Cole]

Don't have much to say:

Had a Cantenna from Heath in the 60's - knocked over; spilt mineral 
oil on the floor, threw can away!

I have acquired "dry" loads over the years rated into UHF and 
sometimes to mw at flea markets and swaps.  My highest power load is 
500w Sierra with power meter and switch for 150 or 500w (probably 
good to 1000-MHz).  Have a couple Bird terminations rated 50w.  Most 
can handled double their rating for short duration.

The hardest duty on my loads is when optimizing the output of a new 
unit where I'm keyed up longer than I should.

But I do have a question on how adjusting a tuner into a 50-ohm load 
saves one from transmitting a signal once the tuner is connected to 
an antenna that may not be 50-ohms.  On 600m my inverted-L is Z = 0.8 
+j680.  Tuning into a 50-ohm load does nothing to help match the 
antenna.  The amplifier is solid state with input and output 
transformers (no adjustment).

I think, unless you use a high power tetrode or triode, that no one 
tunes amplifiers anymore.  Solid state amps are broadband and need LP 
filters to keep from amplifying harmonics.  BTW my 2m-8877 is capable 
of 2000w* RF output so pretty hard to find a dummy load to take 
that.  Fortunately the amp does not change much so very little tuning 
is ever needed (of course I am on a small segment of one band about 
200-KHz wide).  Of course the answer is to tune antenna at lower 
power and hope the High Power amp will always be looking at 50-ohms.

I do not have a QRO 2m antenna tuner but the antenna SWR < 1.25 so 
only the anode tuning needs a light adjustment occasionally (loading 
has not be adjusted for 8 years).  My "dummy load" has 19.2 dBd gain 
and radiates well.

*I operate at 1365w CW which allows for about 9% variance in meter 
accuracy to stay legal.

73, Ed - KL7UW
http://www.kl7uw.com
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