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Author Topic: DUMMY LOAD FOR POWER SUPPLIES  (Read 3212 times)
N9LCD
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Posts: 175




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« on: September 16, 2012, 07:25:06 PM »

I had a problem with a HP linear power supply; the output voltage under load would shoot-up to about 22 Volts.  I was in danger of cremating my IC-271A.

I hit upon using 12 Volt light bulbs as the dummy load.  I found 12 volt, 50 watt light bulbs by Ancor at a local marine supply house.  The bulbs are rated at 4.17 "design" amps and screw into a standard light bulb socket.

Besides being a good dummy load, the bulbs are good for a work light for your vehicle or lighting for nocturnal field day or EmComm operations.

N9LCD     
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K5LXP
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« Reply #1 on: September 16, 2012, 08:54:24 PM »


What did those bulbs cost?  I've gotten them at Lowe's but they're pretty expensive.

The subject of power supply loads was recently discussed:

http://www.eham.net/ehamforum/smf/index.php/topic,84880.0.html


Mark K5LXP
Albuquerque, NM
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N9LCD
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Posts: 175




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« Reply #2 on: September 17, 2012, 12:47:34 PM »

The bulbs come two to a pack.  The price was about $8.00 at West Marine in Chicago.

You might be able to find other brands of 12-volt bulbs.  I used to have a 100-watt G.E. bulb in a "work light" for changing tires at night.

73!

N9LCD
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WB6BYU
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Posts: 13335




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« Reply #3 on: September 17, 2012, 04:42:02 PM »

I use the dual-beam headlamps that I take out of my car after one filament goes out.
The second filament (usually high beam) makes a good test load.
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KB4QAA
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Posts: 2407




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« Reply #4 on: September 18, 2012, 10:21:46 AM »

I've used automotive headlights at work for testing.
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KA5IPF
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« Reply #5 on: September 18, 2012, 11:11:48 AM »

Place I worked at in the past had a large ball/wad of wire in a corner. When I inquired was informed it was the test load for the 50A Astrons.

In the past they got the surplus reels of wire from the telephone company. 16-20ga usually in 1000' reels. Calculate the resistance needed and start unreeling. Check it with an ohmmeter. Make a big ball of it and hook it up. Air cooled load.

Until copper prices went stupid cheap too...

Clif

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SWMAN
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Posts: 571




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« Reply #6 on: September 18, 2012, 12:32:05 PM »

 I use a 12 volt  50 watt  MR16(EXN) lamp. It is a small quartz flood lamp. You can buy them at almost any store nowdays. They are alot easier to find than the other bulbs mentioned. Watch out though, they get hot fast. They draw about 4.2 amps at 12 volts.
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KE4DRN
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Posts: 3729




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« Reply #7 on: September 19, 2012, 07:13:44 PM »

hi,

H6054 headlight from recycling yard about $2,
cut the wires a few feet before the bulb socket,
each 35W, per filament, this is dual beam so
you will pull 70W at 12V with one bulb.

I got two wired up with switch to run low beam
or both high and low beams.

They do get warm but a lot safer since it is
sealed beam lamp.

73 james
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N8CMQ
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Posts: 373




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« Reply #8 on: October 01, 2012, 09:28:24 AM »

Lamps have been used for loads even at RF.
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