[Amps] 2500 W oil/water load ratings

[John T. M. Lyles]

Paul and John,
Thanks for juggling my brain. Yes, I stand corrected. I was thinking 
about the little Bird 1 kW water load, that is stricktly water 
cooled, by water flowing over and inside a single cermet resistor 
tube. They use that technology up into the 50 kW water loads as well, 
and Altronics makes it up to 200 kW. What i replied to was referring 
to those types of loads. The Bird 8230, now that I look in a Bird 
catalog, is just like the 1kW oil filled boxes except having the 
water tubing. Having oil immersion cooling does wonders for the load, 
as it has good heat transfer,and adds dielectric breakdown strength 
around the element inside.

As for the Bird 8141 250W oil filled load, I would agree that you 
could run it higher for a short time, but keep an eye on the 
temperature, add fans, watch the rubber bladder on the end. 1.5 kW is 
a big multiplier over the CW rating of that load.

I have two Altronics 200 kW film loads hooked up through a 3 dB 
hybrid power splitter at work, made from 6 1/8 line, for an upcoming 
test of new 500 kW tetrode power amplifier. It will be pulsed 
however, and average power is more like 70 kW. It would have been 
destructive to run a single load at that peak power, with 10% DF, 
according to discussions with the manufacturer. So i paralled them.

73 and happy holiday,
John
K5PRO


>Hi John
>Are we talking about the same type loads?  My 2500 watt load uses an oil
>dielectric that is cooled with a water loop immersed in the oil.  It could
>be a Bird 8230 but it's marked with a military number, it looks the same and
>is rated the same, 200 watts without water and 2500 with circulation.  I
>have run this load at 6KW SSB for short periods with no apparent damage.
>
>I've haven't tried bacon but the spiders in the cooling fins leave in a
>hurry!!
>73, from rainy Oregon, Paul
>
>PAUL HEWITT
>WD7S PRODUCTIONS
>QRO HOMEBREW COMPONENTS
>http://wd7s.home.att.net

>Date: Sat, 13 Dec 2003 18:58:15 -0500
>From: "John" <brazos at rochester.rr.com>
>To: <amps at contesting.com>
>Subject: [Amps] Re: Amps Digest, Vol 12, Issue 29
>Message-ID: <006601c3c1d4$fb28f9e0$28a0ac44 at aoldsl.net>
>References: <20031213170026.1858E31A100 at dayton.akorn.net>
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>Hi Cliff , I just got a bird 8141 dummy load from bird and it is rated at
>250 watts continuous that should translate to well over 1.5 KW  for short
>periods of time .  Thiswas told to me by a dealer in these surplus dummy
>loads.  check with Max Gain systems in marietta GA.  John