[TowerTalk] Dummy Load Rating

[Mike & Becca Krzystyniak]

Hi John,

    I have several loads of the same or similar ratings.  I found you can
pro-rate the continuous duty ratings by 2-3X in short key ups, or 50% duty
cycle CW.  
    The metric I watch is thermal rise. I try to keep the temp rise in the
range of 25-50C.
    Just remember there is a thermal latency in heat transferring to the
surface, but the inside the load dissipates power the second you hit it with
RF. 

    Over a longer period of time something that is blistering hot to the
touch means the resistor element itself is probably in the range of
150-175F.
    I would avoid letting it reach 100C (boils the spit off your finger
tip).  :-(

Mike K9MK


-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
john at kk9a.com
Sent: Friday, December 04, 2015 12:42 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Dummy Load Rating

I have a couple of Bird dummy loads, one is rated at 500 watts and one is
1000 watts, continuous duty. I have never seen an intermittent duty rating.
Does anyone have an idea how much power these can safely handle for a short
duration?

John KK9A

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