Dummy load for KPA3?
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I'm considering adding the amp to my k3/10. I see a 50w dummy load is reqd
for setup. Any recommendations? Should I get a 100w one instead? Build vs buy? 73 jim ab3cv ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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I'd buy this:
https://www.ridgeequipment.com/store/dummyloads.html 75 watts and $12. I've been happy with mine bought a couple of years ago. 73, Bob K2TK ex KN2TKR (1956) & K2TKR On 2/7/2012 10:11 AM, Jim Miller wrote: > I'm considering adding the amp to my k3/10. I see a 50w dummy load is reqd > for setup. Any recommendations? Should I get a 100w one instead? > > Build vs buy? > > 73 > > jim ab3cv > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Jim AB3CV
I have acquired a number of dummy loads over the years.
A lot depends on your ultimate needs. If you buy the minimum now, you might end up buying something larger later. For the purposes of K3/100 Tx Gain Calibration, you'll need a dummy load that can dissipate 50 watts for short periods. Tx Gain calibration holds the key down on each of 6 frequencies at the 5 and 50 watt power levels for about 4-10 seconds at a time. If you're careful, that can be handled by something as small as an MFJ-261 that is rated for 30 watts or 100 watts "peak". I burned mine up while testing Tx Gain Calibration when I stepped through the code with a debugger and left the transmitter on for too long. I didn't replace it. It's a very convenient size. I recently bought a pair of 75 watt dummy loads from Ridge Equipment. I'm using them for an antenna tuner project where I want the load to be really just resistive on all interesting frequencies. They come with N connectors, so you might need an SO-239 adapter that Ridge Equipment also sells. I like these very much. They are "like new", and present an SWR < 1.02 up to about 700 MHz. At 3 GHz they get all the way up to 1.12. https://www.ridgeequipment.com/store/dummyloads.html If you eventually expect to use an amplifier, perhaps a higher power dummy load would be a good investment. A "dry" dummy load like an AEA-1500 or Palstar DL-1500 can handle 100 watts for extended periods (10 minutes or so) or 1500 watts for a few (10) seconds. If you need to support key down at full 1500 watt power for a few minutes, you might want a can filled with mineral oil, such as the old Heath Cantenna or Ameritron ADL-2500 or MFJ -2500. If you're testing high power amplifiers for extended periods, you might need to invest in something with a fan, such as the Palstar DL2K, DL5K, Ameritron ADL-2500 or MFJ-265. The high end of these is the Alpha 2100, which reportedly handles 1500 watts indefinitely. It is what RF Concepts calls a "legacy" product, however. I normally think of a dummy load as something I'd use primarily in testing and calibration, but I've recently thought of a good use for it in a contest multi-radio antenna switching project when I need an "antenna" to switch an exciter to during band transitions. I don't want to leave the antenna connection open or shorted while I switch a radio to a band where another nearby radio could be transmitting, so a low power dummy load is just a perfect "antenna" for this. The receiver is somewhat protected from "same band" transmitters, and if the exciter is keyed it won't see a load that exercises the transceiver's protection circuitry. 73 de Dick, K6KR -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Jim Miller Sent: Tuesday, February 07, 2012 7:11 AM To: Elecraft Reflector Subject: [Elecraft] Dummy load for KPA3? I'm considering adding the amp to my k3/10. I see a 50w dummy load is reqd for setup. Any recommendations? Should I get a 100w one instead? Build vs buy? 73 jim ab3cv ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Bob-2
That Ridge Equipment dummy load is very good - I would recommend it
highly for any measurement or calibration work. I would not exceed 75 watts with it. If you want a dummy load to leave connected to your K3 when not in use and general all-around the shack work, you might want to consider building one in a quart paint filled with mineral oil - see: http://www.k4eaa.com/dummy.html - I have two similar dummy loads here in quart cans and a larger one in a gallon can that have served well for many, many years. 73, Don W3FPR On 2/7/2012 11:17 AM, Bob wrote: > I'd buy this: > > https://www.ridgeequipment.com/store/dummyloads.html > > 75 watts and $12. I've been happy with mine bought a couple of years ago. > > 73, > Bob > K2TK ex KN2TKR (1956)& K2TKR > > > On 2/7/2012 10:11 AM, Jim Miller wrote: >> I'm considering adding the amp to my k3/10. I see a 50w dummy load is reqd >> for setup. Any recommendations? Should I get a 100w one instead? >> >> Build vs buy? >> >> 73 >> >> jim ab3cv >> Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Jim AB3CV
thanks all. went with the ridge eqp suggestion.
73 jim ab3cv ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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