I bought mine here.
http://www.ebay.com.au/sch/rfandmicrowaves/m.html?_nkw=dummy+load&_sacat=0&_odkw=&_osacat=0&_trksid=p3911.c0.m270.l1313
73, Alek. VK6APK
On 15/06/2012 7:18 AM, Jim Barber wrote:
> These make it easy:
>
> http://www.ebay.com/itm/4-ea-800-Watt-Hybrid-200-ohm-Load-Resistor-500-mHz-/370454666736?pt=LH_DefaultDomain_0&hash=item5640d19df0#ht_734wt_1396
> <http://www.ebay.com/itm/4-ea-800-Watt-Hybrid-200-ohm-Load-Resistor-500-mHz-/370454666736?pt=LH_DefaultDomain_0&hash=item5640d19df0#ht_734wt_1396>
>
> And no, I'm not shilling for Henry Radio. I just buy RF parts from them
> here and there. :-)
>
> 73,
> Jim N7CXI
>
> On 6/14/2012 4:08 PM, mike@n1ta.com wrote:
>> A few years ago I built something pretty similar to K4EAA's design,
>> which can be found (with great pictures) at:
>> http://www.k4eaa.com/dummy.html. Has worked FB for measuring low power
>> stuff: mostly the radios before the amp. I have a bigger palstar model
>> for amp work, but have often thought of building another homebrew can as
>> well, and upping for 2kW or so. I'm sure with some value tweaking it
>> could be done easily. The LP version cost me under $40.
>>
>> Mike N1TA
>>
>>
>> -------- Original Message --------
>> Subject: [Amps] Dummy Load Blues
>> From: "Jerry Kaidor"<jerry@tr2.com>
>> Date: Thu, June 14, 2012 7:54 pm
>> To: amps@contesting.com
>>
>> Hello,
>>
>> To mess with amps, a good dummy load is a must. I went to my storage,
>> and pulled out a Cantenna of unknown provenance that I had purchased
>> about
>> 30 years ago at a flea market. Not knowing what was in it, I assume it's
>> poisonous PCB transformer oil. I had kept the dummy load in a plastic
>> bucket
>> with a hole for the coax, sealed with coax seal. Now I figured I'd
>> dispose of the old oil, clean it out, and put in fresh mineral oil. What
>> a mess!
>>
>> OK, the old oil is gone; it'll be headed to the local hazardous waste
>> dropoff. The guts are all washed out in hot water and detergent. The
>> heathkit can is toast - rusty and leaking. The silver
>> straps around each end of the resistor are broken. So I can reconstitute
>> this thing with new silver straps ( luckily I have some silver sheet
>> laying around ). And the can - can be replaced with an ordinary one from
>> the paint factory. Only trouble with that is - 1 gallon paint cans are
>> now *plastic*, not metal. I guess it'll still work, just the heat
>> transfer won't be quite as good.
>>
>> I also scored a 250W load cheap on Ebay. Seller said it came out of a
>> cell phone installation. I popped it open - the resistor is the size
>> of a postage stamp! I was messing with one of my SB2-LA's, used that
>> load - figured a momentary toot from the amp wouldn't hurt it. I was
>> wrong. Apparently these little resistors are not only heat limited,
>> but *voltage* limited. I hit transmit, there was a small *pop* and a
>> puff of smoke. Hole burned right through it.
>>
>> There are similar load resistors on sale on Ebay - 800W for IIRC $40.
>> But that's just the resistor, you have to bond it to a heatsink. I
>> have
>> the heatsink from the defunct 250W load - I could machine off a big
>> enough
>> flat spot for the 800W resistor.... failing that, I have a really big
>> heat
>> sink in my junk.
>>
>> - Jerry Kaidor, KF6VB
>>
>>
>>
>>
>>
>>
>>
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--
From sunny Binningup, Western Australia.
http://www.qrz.com/db/vk6apk
http://www.qrz.com/db/vk6ap
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