| Author |
Message |
    
Allagator
Intermediate Member
Username: Allagator
Post Number: 327
Registered: 9-2002
| | Posted on Saturday, June 12, 2004 - 12:27 am: | 
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what would be the best coolent for a homebrew dummyload???
so far i have a 24oz mason jar i am useing for the container and 20x1k 5watt resistors running parallel
witch it came up to a perfect 50 ohm !!
would anyone know how much power it will handle ??
Thanks Allagator !! |
Ca346
Advanced Member
Username: Ca346
Post Number: 818
Registered: 8-2003
| | Posted on Saturday, June 12, 2004 - 9:31 am: |
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Anything (oil) that doesn't have PCB's in it... How about transmission fluid? It won't break down under heat. BUT... You'd be better off with a 1 gallon paintcan than a glass jar. |
Allagator
Intermediate Member
Username: Allagator
Post Number: 328
Registered: 9-2002
| | Posted on Saturday, June 12, 2004 - 12:44 pm: |
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Thanks CA346 !!!! |
Geekster
New member
Username: Geekster
Post Number: 6
Registered: 6-2004
| | Posted on Tuesday, June 15, 2004 - 9:36 pm: |
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You can use mineral oil which is available at health and beauty stores or CVS. I have seen people use motor oil, sand, baby oil, transformer oil to name a few. |
Geekster
Junior Member
Username: Geekster
Post Number: 10
Registered: 6-2004
| | Posted on Wednesday, June 16, 2004 - 7:10 am: |
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Oh forgot,
I would say about 100 watts for maybe 20 seconds (dry no oil)or so. You may get 250 watts for short term. It will really depend on the oil or material used to dissipate the heat. We used to put them in paint cans and when filled with mineral oil. You will be able to use it for more power than 250 watts when filled with oil.
I would say probably safe upwards 150 MHz with some db loss. It would depend on your construction lead lengths, and materials used. Should work great for 11 meters.
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Ca346
Advanced Member
Username: Ca346
Post Number: 827
Registered: 8-2003
| | Posted on Thursday, June 17, 2004 - 12:59 am: |
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I went back and looked at my ARRL books and was reminded that the idea of the paint can (metal) was to keep the RF down to a minimal level. There is a great picture of two perforated metal plates welded (soldered) to the lid and center conductor. But I'm not sure how far apart the two metal plates should be? |
Geekster
Junior Member
Username: Geekster
Post Number: 15
Registered: 6-2004
| | Posted on Thursday, June 17, 2004 - 8:35 am: |
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Yes,
I remember seeing that. We used to use them on the dry dummy loads. We could actually tune for a higher frequency range using them.
I forgot about that...
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