[Elecraft] Product Suggestion - 500W Dummy Load

[Tim]

Hi All,
My Cantenna has sat in a bucket since I built it many many years ago.  
No seen it as yet from our house move last month, but have not seem any 
oil stains as yet.  I am sure the boss would have told me!
73
Tim
gm4lm
On 18/09/2015 19:00, Edward R Cole wrote:
> 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
>     "Kits made by KL7UW"
> Dubus Mag business:
>     dubususa at gmail.com
>
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