50 Ohm Load - source?
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I tried to Google it and made it to the OHR Website but could not find it. Somebody please post a URL to a source. Thanks. 73, Jim KG0KP -----Original Message----- From: Elecraft [mailto:[hidden email]] On Behalf Of Ernie Kluft Sent: Sunday, March 29, 2015 6:55 AM To: [hidden email] Subject: [Elecraft] 50 Ohm Load For those still pondering what dummy load to use, consider this... My Cantenna is at least 40 years old and while I should have put a meter on it, I thought that little unit sold by OHR mentioned by others would be worth having.... $51.05 including postage to Dallas and about an hour of my time to carefully build it... Nice little unit... That's one option... Ernie ______________________________________________________________ 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 Message delivered to [hidden email] |
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I found this link:
http://www.ohr.com/index.htm Robie - AJ4F On Sun, Mar 29, 2015 at 4:34 PM, Jim Miller <[hidden email]> wrote: > > I tried to Google it and made it to the OHR Website but could not find it. > Somebody please post a URL to a source. > > Thanks. 73, Jim KG0KP > > > -----Original Message----- > From: Elecraft [mailto:[hidden email]] On Behalf Of > Ernie > Kluft > Sent: Sunday, March 29, 2015 6:55 AM > To: [hidden email] > Subject: [Elecraft] 50 Ohm Load > > For those still pondering what dummy load to use, consider this... > My Cantenna is at least 40 years old and while I should have put a meter on > it, I thought that little unit sold by OHR mentioned by others would be > worth having.... $51.05 including postage to Dallas and about an hour of > my > time to carefully build it... Nice > little unit... That's one option... Ernie > > > > ______________________________________________________________ > 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 > Message delivered to [hidden email] > 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 Message delivered to [hidden email] |
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I just built that RF load kit from OHR. Works as advertised.
At 150 MHz, the impedance is 50 + j2, which is pretty good for metal oxide resistors. At HF, I can't measure any reactance but that's probably due to the SWR meter. The load is convection cooled (flow-through). Kit instructions are clearly written and easy to follow. 73, matt W6NIA On Sun, 29 Mar 2015 16:47:52 +0000, you wrote: >I found this link: > >http://www.ohr.com/index.htm > >Robie - AJ4F > >On Sun, Mar 29, 2015 at 4:34 PM, Jim Miller <[hidden email]> >wrote: > >> >> I tried to Google it and made it to the OHR Website but could not find it. >> Somebody please post a URL to a source. >> >> Thanks. 73, Jim KG0KP >> >> >> -----Original Message----- >> From: Elecraft [mailto:[hidden email]] On Behalf Of >> Ernie >> Kluft >> Sent: Sunday, March 29, 2015 6:55 AM >> To: [hidden email] >> Subject: [Elecraft] 50 Ohm Load >> >> For those still pondering what dummy load to use, consider this... >> My Cantenna is at least 40 years old and while I should have put a meter on >> it, I thought that little unit sold by OHR mentioned by others would be >> worth having.... $51.05 including postage to Dallas and about an hour of >> my >> time to carefully build it... Nice >> little unit... That's one option... Ernie >> >> >> >> ______________________________________________________________ >> 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 >> Message delivered to [hidden email] >> >______________________________________________________________ >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 >Message delivered to [hidden email] -- "Always store beer in a dark place." -R. Heinlein ______________________________________________________________ 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 Message delivered to [hidden email] |
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In reply to this post by hf4me
I often wonder about people who will buy expensive (but excellent) radio's,
then baulk at spending a few bucks, quid's or ?, on basic test kit like a half decent dummy load! Am I missing something? Dave G0WBX. ______________________________________________________________ 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 Message delivered to [hidden email] |
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Yes, you are.
Dummy loads are not fun, like nice radios. When I built a Heathkit HW100, 45 years ago, I needed a dummy load to align the transmitter section. Not having one, and having just spent all my discretionary funds on the radio, I used a pencil lead to make a resistor element. I had to experiment with different drafting pencils to find the correct resistance. I carefully removed the wood with a razor blade, and attached clip leads at the points that gave me 50 ohms. I dunked the result in a container of motor oil (probably not the best choice), and finished the alignment. It worked well and was a one shot deal. Later, following instructions in a ham radio magazine, I built a dummy load using two copper disks and 10 resistors. This was also installed in a quart can filled with oil of some kind. I put the dummy load under my shack and ran coax up to my rigs. Also worked well. Now, I use an Elecraft 20 watt load, and have used it for short periods of time at higher power to make quick measurements. This included the alignment work on my K3/100. 73, Rick Dettinger K7MW On Mar 30, 2015, at 2:43 PM, Dave Baxter wrote: > I often wonder about people who will buy expensive (but excellent) radio's, > then baulk at spending a few bucks, quid's or ?, on basic test kit like a > half decent dummy load! > > Am I missing something? > > Dave G0WBX. ______________________________________________________________ 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 Message delivered to [hidden email] |
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Good stuff Rick. I bought and built the OHR-100RFL because it was
priced reasonable, it was 100W rated, and I figured with all my QRP rigs it would last my ancestors a couple dozen lifetimes. I have a couple other 20W homebrew loads around here too...can never find one when I need it though...the 100RFL sits in a handsome cabinet on my bench where is it handy and usable all the time. No sir...can't beat a good dummy load. On 3/30/2015 7:17 PM, Rick Dettinger wrote: > Yes, you are. > Dummy loads are not fun, like nice radios. > When I built a Heathkit HW100, 45 years ago, I needed a dummy load to align the transmitter section. > Not having one, and having just spent all my discretionary funds on the radio, I used a pencil lead to make a resistor element. > I had to experiment with different drafting pencils to find the correct resistance. I carefully removed the wood with a razor blade, and attached clip leads at the points that gave me 50 ohms. I dunked the result in a container of motor oil (probably not the best choice), and finished the alignment. It worked well and was a one shot deal. > Later, following instructions in a ham radio magazine, I built a dummy load using two copper disks and 10 resistors. This was also installed in a quart can filled with oil of some kind. I put the dummy load under my shack and ran coax up to my rigs. Also worked well. > Now, I use an Elecraft 20 watt load, and have used it for short periods of time at higher power to make quick measurements. This included the alignment work on my K3/100. > > 73, > Rick Dettinger K7MW > > > > > > > > > > On Mar 30, 2015, at 2:43 PM, Dave Baxter wrote: > >> I often wonder about people who will buy expensive (but excellent) radio's, >> then baulk at spending a few bucks, quid's or ?, on basic test kit like a >> half decent dummy load! >> >> Am I missing something? >> >> Dave G0WBX. > ______________________________________________________________ > 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 > Message delivered to [hidden email] > ______________________________________________________________ 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 Message delivered to [hidden email] |
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I can just picture the conversation:
Support Tech: "What are you using for a dummy load?" Ham: "A pencil lead". Support Tech: <silence> Made my day. 73, Bill W6WRT ______________________________________________________________ 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 Message delivered to [hidden email] |
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In reply to this post by g8kbvdave
Because it's the piddely stuff like connectors and coax and dummy loads, etc...that will run you out of the hobby. Ask any boat owner. There is a reason why they call boats holes in the water you pour money into. Same thing for planes at engine overhall time.
If you can save bucks by building a 130W dummy load in a cheap 1 qt/ paint can with a handfull of resistors and some mineral oil why not? As the great philosopher Angus Young of AC/DC once said..."this ain't high opera". On Mon, 30 Mar 2015 22:43:59 +0100 Dave Baxter <[hidden email]> wrote: > I often wonder about people who will buy expensive (but excellent) radio's, > then baulk at spending a few bucks, quid's or ?, on basic test kit like a > half decent dummy load! > > Am I missing something? > > Dave G0WBX. > ______________________________________________________________ > 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 > Message delivered to [hidden email] -- R. Kevin Stover AC0H ______________________________________________________________ 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 Message delivered to [hidden email] |
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On Mon,3/30/2015 5:37 PM, Kevin Stover wrote:
> Because it's the piddely stuff like connectors and coax and dummy loads, etc...that will run you out of the hobby. Ask any boat owner. There is a reason why they call boats holes in the water you pour money into. Same thing for planes at engine overhall time. The problem is that connectors and coax and dummy loads are the sorts of things that can cause things to grind to a halt if they fail, or are not of good quality. A dummy load or SWR bridge that's out of spec can cause us to make bad decisions about matching in our system, or to mis-calibrate it. El-cheapo coax (or coax that's been wet inside) and junk connectors (and connectors that are badly installed) all cause failures that can cost big bucks. And all of these problems can be VERY hard to find. I recently spent more than $1,200 finding and fixing a problem with my SteppIR that turned out to be a piece of coax (good stuff) that got stepped on near a connector (good connector). It was right outside the shack, jumping from 7/8-in hard line to my "ground entry window." This stuff isn't as sexy as a radio or big antenna, but it's equally important. The way to economize on things like this is to find good stuff used/surplus, not cheap junk. 73, Jim K9YC ______________________________________________________________ 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 Message delivered to [hidden email] |
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In reply to this post by g8kbvdave
I think that attitude spells the difference between "appliance
operators" and those who are willing to check out, and otherwise examine their ham gear. How many "transceiver" problems turn out to be problems with the antenna system? The number is larger than many are willing to admit. In the long past, every ham had at least a few test tools - dummy load (even if it was a light bulb), and means of measuring RF and SWR (even if it was a pair of #47 lightbulbs on a piece of 300 ohm twinlead) - and that gear was used to determine if the transmitter was capable of producing power and if the antenna system was capable of accepting the RF power. There were times when precise and accurate measurement gear was outside the budget of most hams, so we used substitute methods that gave us some indication that our transmitters and antennas were performing OK. Today, reasonably good dummy loads and wattmeters are well within the budget of the typical ham. When we are willing to spend $1000 or more on a transceiver, I find it foolish economy to decline to spend $100 for a few pieces of test gear to assure ourselves that that $1000+ transceiver is running properly. It seems some hams would rather 'send it back to the factory for a checkout' than to make some simple measurements in the shack - the cost of that trip to the factory will exceed the cost of the equipment required to do simple testing of the equipment in place. It does seem like false 'economy' to me, but I know there are some who will do just that. And - when the transceiver returns with "no trouble found" because the problem was actually in the antenna system, that is not helpful. The cause of the problem could have been identified if a dummy load and a wattmeter had been available and willing to be used for some simple tests. The precision of the dummy load and wattmeter need not be extreme for tests of this sort - even gear with a 20% or greater error can give clues to the cause of failure in cases like that. Yes, I now have precision dummy loads and wattmeters whose calibration is NIST tracable, but I use those for precision measurements. To do a 'sanity check' of where the problem may be does not require anything near that precision or accuracy. As I have stated in the past, every hamshack should have a dummy load capable of handling the maximum output of that station. It need not be exactly 50 ohms non-reactive (unless it is being used for calibration), but it should be a part of the diagnostic tools available in every hamshack. 73, Don W3FPR On 3/30/2015 5:43 PM, Dave Baxter wrote: > I often wonder about people who will buy expensive (but excellent) radio's, > then baulk at spending a few bucks, quid's or ?, on basic test kit like a > half decent dummy load! > > Am I missing something? > > ______________________________________________________________ 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 Message delivered to [hidden email] |
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Very well said, don.
If ham does not need a new dummy load, there are a lot nice ones available in the used market at a very reasonable price. Nowadays, frequency counter, RF watt meter and DMM are all available at a much affordable price. Even a temperature controlled soldering iron is not expensive. All those items were totally out of the question when I started my hobby at the age of 12. Let us enjoy our hobby in a much affordable way now. 73 Johnny VR2XMC 寄件人︰ Don Wilhelm <[hidden email]> 收件人︰ [hidden email] 傳送日期︰ 2015年03月31日 (週二) 12:06 PM 主題︰ Re: [Elecraft] 50 Ohm Load - source? I think that attitude spells the difference between "appliance operators" and those who are willing to check out, and otherwise examine their ham gear. How many "transceiver" problems turn out to be problems with the antenna system? The number is larger than many are willing to admit. In the long past, every ham had at least a few test tools - dummy load (even if it was a light bulb), and means of measuring RF and SWR (even if it was a pair of #47 lightbulbs on a piece of 300 ohm twinlead) - and that gear was used to determine if the transmitter was capable of producing power and if the antenna system was capable of accepting the RF power. There were times when precise and accurate measurement gear was outside the budget of most hams, so we used substitute methods that gave us some indication that our transmitters and antennas were performing OK. Today, reasonably good dummy loads and wattmeters are well within the budget of the typical ham. When we are willing to spend $1000 or more on a transceiver, I find it foolish economy to decline to spend $100 for a few pieces of test gear to assure ourselves that that $1000+ transceiver is running properly. It seems some hams would rather 'send it back to the factory for a checkout' than to make some simple measurements in the shack - the cost of that trip to the factory will exceed the cost of the equipment required to do simple testing of the equipment in place. It does seem like false 'economy' to me, but I know there are some who will do just that. And - when the transceiver returns with "no trouble found" because the problem was actually in the antenna system, that is not helpful. The cause of the problem could have been identified if a dummy load and a wattmeter had been available and willing to be used for some simple tests. The precision of the dummy load and wattmeter need not be extreme for tests of this sort - even gear with a 20% or greater error can give clues to the cause of failure in cases like that. Yes, I now have precision dummy loads and wattmeters whose calibration is NIST tracable, but I use those for precision measurements. To do a 'sanity check' of where the problem may be does not require anything near that precision or accuracy. As I have stated in the past, every hamshack should have a dummy load capable of handling the maximum output of that station. It need not be exactly 50 ohms non-reactive (unless it is being used for calibration), but it should be a part of the diagnostic tools available in every hamshack. 73, Don W3FPR On 3/30/2015 5:43 PM, Dave Baxter wrote: > I often wonder about people who will buy expensive (but excellent) radio's, > then baulk at spending a few bucks, quid's or ?, on basic test kit like a > half decent dummy load! > > Am I missing something? > > ______________________________________________________________ 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 Message delivered to [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] |
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