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Author Topic: Dummy Load >100W  (Read 375 times)

KB1NO

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Dummy Load >100W
« on: September 02, 2021, 10:38:13 PM »

I'm looking for a dummy load that can take 500 Watts for more than a few seconds.  My preference is for a dry type vs the leaking paint can type.
Some of the dry ones I see advertised seem to be rated very optimistically.  There is a fellow on eBay selling surplus 500W dry dummy loads for $65 but no duration of power is specified.  He is in Israel, so the shipping is expensive.   
Does anyone have experience with those dummy loads.  I'd be interested in comments on their robustness,  or other alternatives.
Thanks,
John, KB1NO
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VK6HP

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Re: Dummy Load >100W
« Reply #1 on: September 02, 2021, 11:31:14 PM »

John,

Amongst my collection of loads I have an air-cooled Vectron DL-650M, which will take 1.5 kW for 10 s, 500 W for 40 s  and about 200 W indefinitely according to the de-rating curve on the side.  It's quite good to UHF in its frequency characteristics but one weakness is that the slotted box is relatively leaky from the RF viewpoint. However, that's sometimes a plus in putting together an effective monitor arrangement.

You might also be able to pickup a used better quality unit such as Bird 500-WA or WT series air-cooled attenuator or dummy load ("coaxial termination").  One of my more useful bits of test gear is a Bird 300-WA 40 dB power attenuator which is effectively a dummy load and which, when teamed with a small external supplementary attenuator (10 dB) makes for a nice accurate spectrum analyser interface (e.g. 100 W in giving 1 mW out).

73, Peter.
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K7MEM

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Re: Dummy Load >100W
« Reply #2 on: September 03, 2021, 02:09:03 AM »

I don't have the needs that you have, so I use a Drake DL-300. I also have a home brew dummy load that is good for about 350 Watts. But there is a DL-1000. You can extend the load time with a optional cooling fan. With the fan, the DL-1000 will handle 500 watts for 5 minutes, or more. There is one available, with fan, on EBay for around $200.
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Martin - K7MEM
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KB2WIG

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Re: Dummy Load >100W
« Reply #3 on: September 03, 2021, 07:35:29 AM »



I picked up a 500W Bird for ~ $120 on epay.  Fer some insight, check this out....

http://wireless-girl.com/Projects/BirdDummyLoad.html

KLC
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K1KIM

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Re: Dummy Load >100W
« Reply #4 on: September 03, 2021, 07:44:44 AM »



I picked up a 500W Bird for ~ $120 on epay.  Fer some insight, check this out....

http://wireless-girl.com/Projects/BirdDummyLoad.html

KLC

You need to hunt around and have patience. The Birds are going for around $250 with shipping right now. Maybe a Hamfest.
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So Many Toys.......So Little Time!

WA2EIO

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Re: Dummy Load >100W
« Reply #5 on: September 03, 2021, 09:53:07 AM »

I also recommend a Bird, (which are oil cooled at that power level, but neater and less likely to leak than a paint can!) but they are expensive  and shipping costs will bring then up even more.  Keep an eye on Ebay and you might get lucky.  If you can get to a hamfest (if any are running in your area!) you might find a better deal.

You may be able to use one of the long 'dry' 1.5 KW loads (like the MFJ 264, or others of similar design)  along with a cooling fan to increase the length of time you can use it in continuous operation.
« Last Edit: September 03, 2021, 09:59:04 AM by WA2EIO »
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K0UA

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Re: Dummy Load >100W
« Reply #6 on: September 03, 2021, 04:59:29 PM »

How about making your own water cooled one?
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73  James K0UA

KB1NO

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Re: Dummy Load >100W
« Reply #7 on: September 03, 2021, 06:44:45 PM »

Thanks all, for your good suggestions and the helpful link with info on the Bird.
I should build one with resistors, a big heatsink and fan, but antenna projects are ahead of it
I will keep an eye out for a Bird at the NE Ham Xposition.   If not I'll go with the $100 MFJ + fan.

73,
John , KB1NO
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KE0ZU

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Re: Dummy Load >100W
« Reply #8 on: September 03, 2021, 07:28:36 PM »

Like Kevin kb2wig said look on the bay.   I picked up an ugly Military 600W Bird load a few years ago for 45 bucks.   Thats 600 Watts all day, and it's handled continuous two tone 1500 Watt tests for a couple minutes numerous times.   Longer than most tests should take.

« Last Edit: September 03, 2021, 07:30:44 PM by KE0ZU »
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Regards, Mike
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