Re: [Elecraft] Difference in dummy loads
Buyer beware. I bought a superb, almost new, almost unused Bird 8141, in its original box and it failed after a short while. Taking it apart it was obvious that it had been well and truly cooked. It must have been hammered. The main connection had corroded and separated from the element. I have photos. The solution was exceedingly cheap and easy: separate the parts from the body, wash with IPA etc, sit contact parts in tomato ketchup for a couple of hours, clean up and re-assemble. David G3UNA/G6CP > On 02 July 2020 at 18:16 Edward R Cole wrote: > > > I bought an air-cooled Bird 8201 rated 500w to 3-GHz from e-bay for > $300. It can handle 1500w for short transmissions. > > 73, Ed - KL7UW >http://www.kl7uw.com > Dubus-NA Business mail: >dubus...@gmail.com > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to d.cut...@ntlworld.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Difference in dummy loads
I bought an air-cooled Bird 8201 rated 500w to 3-GHz from e-bay for $300. It can handle 1500w for short transmissions. 73, Ed - KL7UW http://www.kl7uw.com Dubus-NA Business mail: dubus...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Difference in dummy loads
> On Jul 2, 2020, at 3:42 AM, NW0M wrote: > > Don't over-think this one. For 98% of us hams the MFJ dummy loads will work > fine. > > The MFJ-260C is rated at 300 watts and sells for $50. Looking at the rating curve in the manual, that is 300 W for 30 seconds or 100 W for 90 seconds. For $50, I’d still go with the Oak Hills Research kit. That handles 100 W continuous, no time limit. http://www.ohr.com/rfl100.htm wunder K6WRU Walter Underwood CM87wj http://observer.wunderwood.org/ (my blog) __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Difference in dummy loads
I ordered the MFJ-260C. Thanks for all the replies! Thanks, Mike NJ2OM > On Jul 2, 2020, at 6:44 AM, NW0M wrote: > > Hi Mike, > > Don't over-think this one. For 98% of us hams the MFJ dummy loads will work > fine. > > The MFJ-260C is rated at 300 watts and sells for $50. > > The MFJ-264 is rated for 1500 watts (an Ohio vendor sells it for $80) if you > think an amplifier is in your future plans. > > 73, Mitch > > > > -- > Sent from: http://elecraft.365791.n2.nabble.com/ > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to mikekopa...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Difference in dummy loads
Hi Mike, Don't over-think this one. For 98% of us hams the MFJ dummy loads will work fine. The MFJ-260C is rated at 300 watts and sells for $50. The MFJ-264 is rated for 1500 watts (an Ohio vendor sells it for $80) if you think an amplifier is in your future plans. 73, Mitch -- Sent from: http://elecraft.365791.n2.nabble.com/ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Difference in dummy loads
I have a MFJ-264 which is rated for 100W more or less continuously and 1500W for 10 seconds. It seems to work within its specs. I've used it at up to 1KW or so. I assume it is like most MFJ equipment, it does what it is specified to do, but don't push it even a little bit beyond. 73 Bill AE6JV --- Bill Frantz| There's nothing so clear| Periwinkle (408)348-7900 | as a design you haven't | 150 Rivermead Rd #235 www.pwpconsult.com | written down. - Dean Tribble| Peterborough, NH 03458 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Difference in dummy loads
The difference between a "dry" and an "air cooled"? I think they are the same. The difference is with "oil cooled". Heathkit used to sell a "Cantenna" which was a dummy load in a gallon paint can. Add your own transformer oil. IIRC it was rated for a KW for a short period. Ken WA8JXM On Wed, Jul 1, 2020 at 5:45 PM NJMike wrote: > I need to purchase a dummy load for use with my K2/100. What's the > difference between a dry dummy load and an air cooled dummy load? Which is > better? > > Thanks, > Mike NJ2OM > > > > -- > Sent from: http://elecraft.365791.n2.nabble.com/ > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to wa8...@gmail.com > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Difference in dummy loads
A dry dummy load is good for up to its power rating - but do not exceed that rating. The air cooled dummy loads not only require power for the fan, but may be over-rated for their power spec. I prefer dry or oil immersed dummy loads. A good dummy load should present a 1.0 SWR for all the bands of interest. Check with an antenna analyzer. If you have access to a vector analyzer, it should show 50 ohms resistive and zero reactance at all frequencies of interest. Those home-built with resistors can usually be OK up through 30 MHz, but may fail at 50 MHz and above - and that includes the 'cantenna' types (oil immersed resistors). careful construction is required to reduce the inductance involved in the mounting and assembly. I have 3 'cantenna' type dummy loads, two for 150 watts In quart cans and one for 1000 watts in a gallon can. They are OK up through 30 MHz, but not above that level. They are good for loads on the transmitter, but are not sufficient for precise measurement. I also have 2 precision dummy loads that are good up into the GHz region. Those are the ones that I use for measurements (up to 100 watts) And for the K3 TX Gain calibration. I have another that I rate at 50 watts (using a 100 watt Caddock thick film resistor on a heatsink) that is a good load up through 220 MHz. None of mine are air cooled. 73, Don W3FPR On 7/1/2020 7:45 PM, Eric Norris wrote: Basically the same thing. I suggest the Vectronics DL-650 (dx engineering) or a commercial pull from Ridge Equipment. For serious testing, I fire up my 2GHz, 6kW water-cooled dummy load--louder than 10 KPA-1500s on PCP. Always get more capacity than you need. --because you'll need it later. If you get an amp, a high power dummy load is essential for tracking down possible RFI. I keep a 50-watt dummy load on ANT2 of the K3S for a quick TXGN CAL, and a DL-2500 on ANT2 of the KPA1500. But then, I love the smell of a hot dummy load in the morning. It smells like...radio. 73 Eric WD6DBM On Wed, Jul 1, 2020, 2:44 PM NJMike wrote: I need to purchase a dummy load for use with my K2/100. What's the difference between a dry dummy load and an air cooled dummy load? Which is better? __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Difference in dummy loads
Basically the same thing. I suggest the Vectronics DL-650 (dx engineering) or a commercial pull from Ridge Equipment. For serious testing, I fire up my 2GHz, 6kW water-cooled dummy load--louder than 10 KPA-1500s on PCP. Always get more capacity than you need. --because you'll need it later. If you get an amp, a high power dummy load is essential for tracking down possible RFI. I keep a 50-watt dummy load on ANT2 of the K3S for a quick TXGN CAL, and a DL-2500 on ANT2 of the KPA1500. But then, I love the smell of a hot dummy load in the morning. It smells like...radio. 73 Eric WD6DBM On Wed, Jul 1, 2020, 2:44 PM NJMike wrote: > I need to purchase a dummy load for use with my K2/100. What's the > difference between a dry dummy load and an air cooled dummy load? Which is > better? > > Thanks, > Mike NJ2OM > > > > -- > Sent from: http://elecraft.365791.n2.nabble.com/ > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to norrislawfi...@gmail.com > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Difference in dummy loads
__ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Difference in dummy loads
An air-cooled dry dummy load is just fine for 100 W. I like the Oak Hills Research RFL-100 kit. $50 and easy to build. It uses twenty 5 W resistors. http://www.ohr.com/rfl100.htm I wrote up my build of that kit here. https://observer.wunderwood.org/2016/12/31/building-a-dummy-load/ If you want to buy instead of build, I’d look at one of the used Bird dummy loads listed here. There are other sites, but this one seems to have a good selection. https://www.nm3e.com/loadSampler.htm#LoadSampler wunder K6WRU Walter Underwood CM87wj http://observer.wunderwood.org/ (my blog) > On Jul 1, 2020, at 2:44 PM, NJMike wrote: > > I need to purchase a dummy load for use with my K2/100. What's the > difference between a dry dummy load and an air cooled dummy load? Which is > better? > > Thanks, > Mike NJ2OM > > > > -- > Sent from: http://elecraft.365791.n2.nabble.com/ > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to wun...@wunderwood.org __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] Difference in dummy loads
I need to purchase a dummy load for use with my K2/100. What's the difference between a dry dummy load and an air cooled dummy load? Which is better? Thanks, Mike NJ2OM -- Sent from: http://elecraft.365791.n2.nabble.com/ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
