Re: [Elecraft] Fw: Don't have a 50W dummy load
Just stop all this and go buy one Lots of them listed under Ham Radio Dummy Load on e-bay at about a buck a watt. I bought a NARDA 40w load with N-connector good to 12.6 GHz for $40 (from a friend on-line). Yeah I had a 100w light bulb and a Heath Cantenna way back Now mine mostly made by Bird, NARDA, M/A, Midwest MW, etc. My 500w is made by Sierra and I paid maybe $50 at a flea market (it has built-in power meter). SWR is not quite 1:1.00 (1.4 as I recall) - so what. 73, Ed - KL7UW http://www.kl7uw.com Kits made by KL7UW Dubus Mag business: 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] Fw: Don't have a 50W dummy load
Checked my Cantenna today, 78 ohms. Took it apart, even measured the raw resistor. Ordered a replacement from Alan W1GA as someone else mentioned. eBay # 221724743523 for description and options Easy disassembly and price war right ... $24.50 shipped. Thanks for all the info on DL's. 73 Dwight NS9I On 3/26/2015 12:17 PM, Edward R Cole wrote: Just stop all this and go buy one Lots of them listed under Ham Radio Dummy Load on e-bay at about a buck a watt. I bought a NARDA 40w load with N-connector good to 12.6 GHz for $40 (from a friend on-line). Yeah I had a 100w light bulb and a Heath Cantenna way back Now mine mostly made by Bird, NARDA, M/A, Midwest MW, etc. My 500w is made by Sierra and I paid maybe $50 at a flea market (it has built-in power meter). SWR is not quite 1:1.00 (1.4 as I recall) - so what. 73, Ed - KL7UW http://www.kl7uw.com Kits made by KL7UW Dubus Mag business: 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 ns9i2...@bayland.net __ 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] Fw: Don't have a 50W dummy load
I think I have a roll of 12 Ohm 2w resistors at home. If you use 9 in series and 8 in series, then connect those two stacks in parallel, you will get 50.8 ohms, and I think about 20w of power handling...not sure on the power...if someone wants to run that through the Cray and get the exact number, I'd be thrilled to know it. I will give away a set of 17 resistors to anyone that mails me a postage paid, 4 by 6 inch, padded envelope. I think two stamps will do it...maybe three if you are having doubts. I have used these in homebrew dummy loads and crammed it in a Altoids tinyou need to supply a connector and the Altoids tin. My address is good on QRZ... BUT WAIT UNTIL I GET HOME TONIGHT TO MAKE SURE I STILL HAVE THEM. The spool had about 400 on it...so I hope I have it. I'll post again tonight. 73 de KB9BVN Brian Murrey On Thu, Mar 26, 2015 at 2:26 PM, Richard Solomon w1...@earthlink.net wrote: You can often find Dummy loads at your local Ham Flea. I found two 50 Watt Birds for $10 each at the last one. 73, Dick, W1KSZ On 3/26/2015 11:15 AM, Fred Jensen wrote: Mine works fine at 220, VSWR on 440 is about 1.3:1 and rising fast. On the QRP one I made, I left about 1 leads on the resistors, I had a small brass tube to connect the center conductor down to the bottom plate and I didn't want to cut it. VSWR on 6 meters is 1.6:1. 73, Fred K6DGW - Northern California Contest Club - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015 - www.cqp.org On 3/25/2015 8:13 PM, Charlie T, K3ICH wrote: Yes, but the inductances are all in parallel. I built a decent dummy load out of 24, 1200 Ohm, 10 watt wire wound resistors all in parallel between two squares of fiberglass PC board. The SWR was only about 1.2:1 on 15 Meters and about 1.5:1 on 10 meters. Admittedly, not a perfect load, but certainly adequate for the low bands just to soak up some RF. 73, Charlie k3ICH If you're going to use the paralleled metal film resistor construction method, be sure to keep the resistor leads short and spaced them from each other. Lead inductance will start to become a factor on 6 m and up. I built mine with 40 2K 2W resistors and it works find at 100W if used intermittently. It's air cooled. Don't know how much putting it in oil would improve the dissipation. __ 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 w1...@earthlink.net __ 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 kb9...@gmail.com -- 73 de KB9BVN Brian Murrey __ 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] Fw: Don't have a 50W dummy load
Mine works fine at 220, VSWR on 440 is about 1.3:1 and rising fast. On the QRP one I made, I left about 1 leads on the resistors, I had a small brass tube to connect the center conductor down to the bottom plate and I didn't want to cut it. VSWR on 6 meters is 1.6:1. 73, Fred K6DGW - Northern California Contest Club - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015 - www.cqp.org On 3/25/2015 8:13 PM, Charlie T, K3ICH wrote: Yes, but the inductances are all in parallel. I built a decent dummy load out of 24, 1200 Ohm, 10 watt wire wound resistors all in parallel between two squares of fiberglass PC board. The SWR was only about 1.2:1 on 15 Meters and about 1.5:1 on 10 meters. Admittedly, not a perfect load, but certainly adequate for the low bands just to soak up some RF. 73, Charlie k3ICH If you're going to use the paralleled metal film resistor construction method, be sure to keep the resistor leads short and spaced them from each other. Lead inductance will start to become a factor on 6 m and up. I built mine with 40 2K 2W resistors and it works find at 100W if used intermittently. It's air cooled. Don't know how much putting it in oil would improve the dissipation. __ 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] Fw: Don't have a 50W dummy load
You can often find Dummy loads at your local Ham Flea. I found two 50 Watt Birds for $10 each at the last one. 73, Dick, W1KSZ On 3/26/2015 11:15 AM, Fred Jensen wrote: Mine works fine at 220, VSWR on 440 is about 1.3:1 and rising fast. On the QRP one I made, I left about 1 leads on the resistors, I had a small brass tube to connect the center conductor down to the bottom plate and I didn't want to cut it. VSWR on 6 meters is 1.6:1. 73, Fred K6DGW - Northern California Contest Club - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015 - www.cqp.org On 3/25/2015 8:13 PM, Charlie T, K3ICH wrote: Yes, but the inductances are all in parallel. I built a decent dummy load out of 24, 1200 Ohm, 10 watt wire wound resistors all in parallel between two squares of fiberglass PC board. The SWR was only about 1.2:1 on 15 Meters and about 1.5:1 on 10 meters. Admittedly, not a perfect load, but certainly adequate for the low bands just to soak up some RF. 73, Charlie k3ICH If you're going to use the paralleled metal film resistor construction method, be sure to keep the resistor leads short and spaced them from each other. Lead inductance will start to become a factor on 6 m and up. I built mine with 40 2K 2W resistors and it works find at 100W if used intermittently. It's air cooled. Don't know how much putting it in oil would improve the dissipation. __ 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 w1...@earthlink.net __ 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] Fw: Don't have a 50W dummy load
Brings back memories My cantenna as a kid needed transformer oil. My Dad used to work at the local hydro plant. Got a whole gallon of the best PCB oil no money can buy. 73 Russ KD4JO Sent from my T-Mobile 4G LTE Device Original message From: DGB ns9i2...@bayland.net Date:03/26/2015 1:28 PM (GMT-05:00) To: elecraft@mailman.qth.net Cc: Subject: Re: [Elecraft] Fw: Don't have a 50W dummy load Checked my Cantenna today, 78 ohms. Took it apart, even measured the raw resistor. Ordered a replacement from Alan W1GA as someone else mentioned. eBay # 221724743523 for description and options Easy disassembly and price war right ... $24.50 shipped. Thanks for all the info on DL's. 73 Dwight NS9I On 3/26/2015 12:17 PM, Edward R Cole wrote: Just stop all this and go buy one Lots of them listed under Ham Radio Dummy Load on e-bay at about a buck a watt. I bought a NARDA 40w load with N-connector good to 12.6 GHz for $40 (from a friend on-line). Yeah I had a 100w light bulb and a Heath Cantenna way back Now mine mostly made by Bird, NARDA, M/A, Midwest MW, etc. My 500w is made by Sierra and I paid maybe $50 at a flea market (it has built-in power meter). SWR is not quite 1:1.00 (1.4 as I recall) - so what. 73, Ed - KL7UW http://www.kl7uw.com Kits made by KL7UW Dubus Mag business: 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 ns9i2...@bayland.net __ 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 mundschen...@msn.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] Fw: Don't have a 50W dummy load
When I came home from Vietnam in 1967, my new wife bought me a Swan 500. Our next station was to NASA in Houston. We got settled into an apartment, and I needed to fill my Cantenna so on Sunday [first clue], we went to the local grocery store to get a gallon of Squibb mineral oil. It only came in quarts so I put 4 in the basket. Checking out, the clerk, with a big grin, [second clue] said, You're going to drink all of that, right? Before I could say, Give me a break!, she continued, Because if you're not, I can't sell it to you on Sunday. I answered, Yes, she rang it up, and with the same big grin, said as we left, Hope it works for ya'll. 73, Fred K6DGW - Northern California Contest Club - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015 - www.cqp.org On 3/26/2015 12:53 PM, mundschenk55 wrote: Brings back memories My cantenna as a kid needed transformer oil. My Dad used to work at the local hydro plant. Got a whole gallon of the best PCB oil no money can buy. 73 Russ KD4JO __ 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] Fw: Don't have a 50W dummy load
These are the sort of things i look for at hamfests and other electronic flea markets (what the locals call swap meets). I have several 10W 50 ohm loads, 100W loads, and even one 500W load. All are commercial quality, removed from 2-way or cell sites. And, of course, as others have noted, always bring along a little VOM and look at the DC resistance before buying. :) 73, Jim K9YC __ 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] Fw: Don't have a 50W dummy load
ORIGINAL MESSAGE (may be snipped) On Wed, 25 Mar 2015 12:05:18 -0700, you wrote: The key word is Resistive. REPLY: I have used light bulbs in the olden days, although not for the K3 cal procedure. The trick is to insert a variable cap in series to tune out the reactance. Works well, but has to be retuned for each band of course, and the resistance varies with brightness. Because of the variation, do not use with an automatic antenna tuner or the tuner will constantly seek a correct tune. A real dummy load is better. 73, Bill W6WRT __ 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] Fw: Don't have a 50W dummy load
I suspect the TX Gain Calibration would fail due to High SWR. Yes, TX CAL will do that. You need a good 50 ohm non-reactive dummy load good to 54MHz. Light bulbs worked well with old transmitters that had an output circuit that could match most anything. We did not need tuners back then - but then along came limited range transmitter output circuits which sometimes needed a tuner, but today's transmitters need to see a 50 ohm non-reactive load if they are to work properly - and then tuners became essential - they just moved the matching network out of the transmitter and put the equivalent into another box called an antenna tuner. 73, Don W3FPR On 3/25/2015 2:25 PM, Bob Gibson via Elecraft wrote: HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob W5RG __ 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] Fw: Don't have a 50W dummy load
For the calibration procedure, you need the load to be a known 50 ohm resistive impedance. Using a 100W light bulb will not provide the required impedance, and will produce inaccurate results and possible damage the transceiver. 73, Matt VK2RQ On 26 Mar 2015, at 5:25 am, Bob Gibson via Elecraft elecraft@mailman.qth.net wrote: HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob W5RG - Forwarded Message - From: Warren Merkel hullspee...@gmail.com To: elecraft@mailman.qth.net Sent: Wednesday, March 25, 2015 1:17 PM Subject: Re: [Elecraft] Don't have a 50W dummy load That kit from OHR looks nicely done. I wonder if the pcb was immersed in a gallon can of mineral oil instead of the included case, how much more power could it withstand then? 5x-10x maybe? I could use the enclosure for something else. Otherwise I'd get a full paint can kit off ebay for about the same $. Warren KD4Z On March 24, 2015 5:39:04 PM EDT, Brian kb9...@gmail.com wrote: Excellent advice Don. I bought a 100w dummy load kit from OHR. It's called the RFL-100 and it's about $40, comes in a very nice cabinet, and takes less than an hour to build. It has come in handy more times than I can count. http://www.ohr.com/rfl100.htm Oak Hills has some good goods. 73 de KB9BVN Brian Murrey -- Sent from my Android device with K-9 Mail. Please excuse my brevity. __ 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 w...@yahoo.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 matt.vk...@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
[Elecraft] Fw: Don't have a 50W dummy load
HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob W5RG - Forwarded Message - From: Warren Merkel hullspee...@gmail.com To: elecraft@mailman.qth.net Sent: Wednesday, March 25, 2015 1:17 PM Subject: Re: [Elecraft] Don't have a 50W dummy load That kit from OHR looks nicely done. I wonder if the pcb was immersed in a gallon can of mineral oil instead of the included case, how much more power could it withstand then? 5x-10x maybe? I could use the enclosure for something else. Otherwise I'd get a full paint can kit off ebay for about the same $. Warren KD4Z On March 24, 2015 5:39:04 PM EDT, Brian kb9...@gmail.com wrote: Excellent advice Don. I bought a 100w dummy load kit from OHR. It's called the RFL-100 and it's about $40, comes in a very nice cabinet, and takes less than an hour to build. It has come in handy more times than I can count. http://www.ohr.com/rfl100.htm Oak Hills has some good goods. 73 de KB9BVN Brian Murrey -- Sent from my Android device with K-9 Mail. Please excuse my brevity. __ 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 w...@yahoo.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] Fw: Don't have a 50W dummy load
Us old guys had tough tube transmitters with widely tunable output networks that made the rigs more tolerant to our general abuse of known electronic theory. Eric KE6US On 26 Mar 2015, at 5:25 am, Bob Gibson via Elecraft elecraft@mailman.qth.net wrote: HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob W5RG __ 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] Fw: Don't have a 50W dummy load
That will cause the owl to blink, thus losing orientation to True North. Mike NF4L On Mar 25, 2015, at 14:25, Bob Gibson via Elecraft elecraft@mailman.qth.net wrote: HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob W5RG __ 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] Fw: Don't have a 50W dummy load
Using a 100W light bulb will not provide the required impedance, and will produce inaccurate results and possible damage the transceiver. True, also - In the old days there was no need to specify *incandescent* light bulb. Wonder what would happen with a CFL or LED lamp (do not try this)? The key word is Resistive. 73, Cliff K3LL -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Matt VK2RQ Sent: Wednesday, March 25, 2015 11:52 AM To: Bob Gibson Cc: Elecraft Reflector Subject: Re: [Elecraft] Fw: Don't have a 50W dummy load For the calibration procedure, you need the load to be a known 50 ohm resistive impedance. Using a 100W light bulb will not provide the required impedance, and will produce inaccurate results and possible damage the transceiver. 73, Matt VK2RQ On 26 Mar 2015, at 5:25 am, Bob Gibson via Elecraft elecraft@mailman.qth.net wrote: HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob W5RG - Forwarded Message - From: Warren Merkel hullspee...@gmail.com To: elecraft@mailman.qth.net Sent: Wednesday, March 25, 2015 1:17 PM Subject: Re: [Elecraft] Don't have a 50W dummy load That kit from OHR looks nicely done. I wonder if the pcb was immersed in a gallon can of mineral oil instead of the included case, how much more power could it withstand then? 5x-10x maybe? I could use the enclosure for something else. Otherwise I'd get a full paint can kit off ebay for about the same $. Warren KD4Z On March 24, 2015 5:39:04 PM EDT, Brian kb9...@gmail.com wrote: Excellent advice Don. I bought a 100w dummy load kit from OHR. It's called the RFL-100 and it's about $40, comes in a very nice cabinet, and takes less than an hour to build. It has come in handy more times than I can count. http://www.ohr.com/rfl100.htm Oak Hills has some good goods. 73 de KB9BVN Brian Murrey -- Sent from my Android device with K-9 Mail. Please excuse my brevity. __ 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 w...@yahoo.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 matt.vk...@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 c...@cfcorp.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] Fw: Don't have a 50W dummy load
Ummm ... several reasons. Resistance component of an incandescent bulb impedance varies with the temperature [brightness] of the filament. They are also somewhat reactive. Push-pull vacuum tubes and link coupling didn't care about SWR, I don't even remember the term in the ham lexicon until the Pi-network and 50 ohm output was invented. They're also not very good at the dummy part. N6BT, of Force 12 fame, is fairly famous for his phased illuminator, 3 300 watt bulbs mounted on his deck railing in a V arrangement on which he worked all continents. More than once I made contacts while using a 100 watt bulb as my dummy load. If you're going to use the paralleled metal film resistor construction method, be sure to keep the resistor leads short and spaced them from each other. Lead inductance will start to become a factor on 6 m and up. I built mine with 40 2K 2W resistors and it works find at 100W if used intermittently. It's air cooled. Don't know how much putting it in oil would improve the dissipation. 73, Fred K6DGW - Northern California Contest Club - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015 - www.cqp.org On Mar 25, 2015, at 14:25, Bob Gibson via Elecraft elecraft@mailman.qth.net wrote: HOW ABOUT A LAMP WITH 100 WATT BLUB, THATS ALL US OLD GUYS HAD! 73s Bob W5RG __ 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] Fw: Don't have a 50W dummy load
Yes, but the inductances are all in parallel. I built a decent dummy load out of 24, 1200 Ohm, 10 watt wire wound resistors all in parallel between two squares of fiberglass PC board. The SWR was only about 1.2:1 on 15 Meters and about 1.5:1 on 10 meters. Admittedly, not a perfect load, but certainly adequate for the low bands just to soak up some RF. 73, Charlie k3ICH If you're going to use the paralleled metal film resistor construction method, be sure to keep the resistor leads short and spaced them from each other. Lead inductance will start to become a factor on 6 m and up. I built mine with 40 2K 2W resistors and it works find at 100W if used intermittently. It's air cooled. Don't know how much putting it in oil would improve the dissipation. __ 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
