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Can't believe the dummy load prices!!

Greg T

WDX-945 (Jazz Singer) Upper Peninsula of Michigan
Sep 18, 2014
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Escanaba, Michigan
OMG! I was just net surfing radio stuff and ran across and wet 1kw dummy load selling for $128.00. I laughed out loud, thinking this was one of those Ebay-type sales. So, I poked around looking at others and could not believe what I was seeing! Cheapest I found was about $85.00 and they went up to $149.00. The reason I mention this is because I bought mine in the mid 90s for $17 and some change. Yes, brand new, in the package, including the mineral oil. Yes, a versa-load. What happened??
 
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You can get a 50Ω 450w flange mount RF resistor good to 1.7GHz for $24 on mouser.


i want to make a DIY dummy load. i love to tinker taking junk and making something out of it. there is a popular Paint Can dummy load which i believe started as a Heath kit called the 'Cantenna'. a paint can filled with Mineral oil to do the cooling. i'm thinking of making a quart sized one as i will never need anything over 100W. i do want a point i could attach scope test leads. just guessing, but the can should help trap the RF. not sure how much more RF you would be emitting with just a resister bolted to a heatsink. perhaps a Faraday cage :unsure:
s-l1600.jpgcantenna-240.jpgimage.jpg image012.jpg
would be interesting how cheap you could make one.
i've heard of Salt Water dummy loads in glass jars. doesn't sound very good for trapping the RF though.

cheers
/richard
 
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i wonder if they can be used for a dummy load? it doesn't say if they are non inductive or not. if they will work for an air cooled dummy load, you can build a 5kw load for only $285. i will totally buy a bunch if they can be used.
Yes it can. Not only is it listed as an RF part for up to 1.75GHz, but the datasheet has a return loss chart. At 27MHz, it looks llike it is just below -25dB (which is an SWR of 1.118). It cannot be too inductive with an SWR of 1.118.
 
Yes it can. Not only is it listed as an RF part for up to 1.75GHz, but the datasheet has a return loss chart. At 27MHz, it looks llike it is just below -25dB (which is an SWR of 1.118). It cannot be too inductive with an SWR of 1.118.

I bought a pair of 100 ohm 800 watt flange mount devices and wired them up in parallel, with each resistor having it's own heatsink. I bought mine from Florida RF. They work well for air cooled high powered loads.
 
nostalgia,,,, my first dummy load back in early 70s was a 100 watt light bulb and light socket , probably just a few dollars but worked for 4 watt cb radios,,,,, i also later had the pl259 and bayonet bulb dummy
 
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i want to make a DIY dummy load. i love to tinker taking junk and making something out of it. there is a popular Paint Can dummy load which i believe started as a Heath kit called the 'Cantenna'. a paint can filled with Mineral oil to do the cooling. i'm thinking of making a quart sized one as i will never need anything over 100W. i do want a point i could attach scope test leads. just guessing, but the can should help trap the RF. not sure how much more RF you would be emitting with just a resister bolted to a heatsink. perhaps a Faraday cage :unsure:
View attachment 63264View attachment 63261View attachment 63262 View attachment 63263
would be interesting how cheap you could make one.
i've heard of Salt Water dummy loads in glass jars. doesn't sound very good for trapping the RF though.

cheers
/richard


There are lots of different ways to add an RF Sample port to a dummy load, but one simple way is to do what you see here (for HF/VHF use):


-40dB is pretty much perfect for connection to your test equipment, and I have found this simple resistor voltage divider option to work very well at HF/VHF. Remember to keep the resistor leads as short as possible.

73


MFJ-264_attenuator_schem.png
MFJ-264_attenuator_calibration.jpg
 
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