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starman wrote in message ...
Dave wrote: I am using a DX-402 (aka Sangean ATS 505). I would be surprised if it had a balanced antenna input, and have been thinking about just clipping the external antenna to my whip after all. I hooked 20 feet of 300 ohm twinlead to a 300/75 ohm transformer and miniplug last night and plugged it in, but the signal strength was about half of what my whip gives me. Therefore, the change in plans. It would be a mistake to connect a good external antenna directly to the whip. The receiver will almost certainly overload. You know the symptoms for overloading now. If you build the low noise inverted-L, the coax can be connected to the external antenna jack with a mini plug. I was planning on running the vertical portion of twinlead that went from ground level/grounding rod/coax up to the eaves over the steel siding, but I could just as easily run the coax up the side of the house, which would put all of the twinlead above the steel siding. Still not "out in the open" but probably the best I can do. Wifey doesn't want anything that obviously says "Hi there, I'm an antenna!" It's funny how women have an aversion to antennas. Must be an esthetic thing. :-) I am beginning to consider running the coax around to the end of the house and up that side, and laying the twinlead along the ridge of the roof from one end to the other. That would be a up a lot higher and a lot more "out in the open." DAVE & STARMAN, - - - - - - - - - - This would be my recommendation - - - - - - - - - - The horizontal section (single wire) of an inverted-L could also run along the roof ridge. The vertical downlead wire would connect to one end of the horizontal section and run down the end wall of the house to the ground. The balun would be located near the ground next to a ground rod. The coax would go from the balun to the receiver. That's the design of the low noise inverted-L except it's better to locate the antenna away from the house when you can. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Unless you have a Target Frequency and Country (Direction) I do not recommend Dipole Antennas for general all around broadband 500kHz to 30MHz Shortwave Listener "SWL" Antennas. iane ~ RHF No problem with the questions. It's nice to see an interesting on topic thread for a change. Thanks for the encouragement. I'm not yet sure what I will end up doing, but I want to make the best decision possible. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
THANK YOU for this link! I especially like the schematic for the MFJ-956.
I'm definetly going to build that. Dave "CW" wrote in message ... The word balun to describe this device, while quite common, is incorrect. Go he www.kc7nod.20m.com Look for matching transformer. "Dave" wrote in message ... Away from the house is not possible. Even if it was, that would put it near the power lines. How would I build a balun? (Websites/links?) |
So, a matching transformer is all I need? I have pretty much decided to use
300 ohm twinlead along the rood ridge with a 300/75 ohm matching transformer to connect it to the coax, and more as needed between the coax and radio. Will that honestly work? Thanks, Dave "starman" wrote in message ... It's an impedance matching transformer or unun. I use the word 'balun' because most people haven't heard the term 'unun'. CW wrote: The word balun to describe this device, while quite common, is incorrect. Go he www.kc7nod.20m.com Look for matching transformer. "Dave" wrote in message ... Away from the house is not possible. Even if it was, that would put it near the power lines. How would I build a balun? (Websites/links?) -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
"RHF" wrote in message m... starman wrote in message ... Dave wrote: I am using a DX-402 (aka Sangean ATS 505). I would be surprised if it had a balanced antenna input, and have been thinking about just clipping the external antenna to my whip after all. I hooked 20 feet of 300 ohm twinlead to a 300/75 ohm transformer and miniplug last night and plugged it in, but the signal strength was about half of what my whip gives me. Therefore, the change in plans. It would be a mistake to connect a good external antenna directly to the whip. The receiver will almost certainly overload. You know the symptoms for overloading now. If you build the low noise inverted-L, the coax can be connected to the external antenna jack with a mini plug. I was planning on running the vertical portion of twinlead that went from ground level/grounding rod/coax up to the eaves over the steel siding, but I could just as easily run the coax up the side of the house, which would put all of the twinlead above the steel siding. Still not "out in the open" but probably the best I can do. Wifey doesn't want anything that obviously says "Hi there, I'm an antenna!" It's funny how women have an aversion to antennas. Must be an esthetic thing. :-) I am beginning to consider running the coax around to the end of the house and up that side, and laying the twinlead along the ridge of the roof from one end to the other. That would be a up a lot higher and a lot more "out in the open." DAVE & STARMAN, - - - - - - - - - - This would be my recommendation - - - - - - - - - - The horizontal section (single wire) of an inverted-L could also run along the roof ridge. The vertical downlead wire would connect to one end of the horizontal section and run down the end wall of the house to the ground. The balun would be located near the ground next to a ground rod. The coax would go from the balun to the receiver. That's the design of the low noise inverted-L except it's better to locate the antenna away from the house when you can. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Unless you have a Target Frequency and Country (Direction) I do not recommend Dipole Antennas for general all around broadband 500kHz to 30MHz Shortwave Listener "SWL" Antennas. iane ~ RHF Gotcha. Thanks for that clarification. I do appreciate it. Dave No problem with the questions. It's nice to see an interesting on topic thread for a change. Thanks for the encouragement. I'm not yet sure what I will end up doing, but I want to make the best decision possible. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Forgot to mention, I was going to connect the conductors on the far end so
as to have a longer single line. One side of the near end would be hanging out in space, in other words, so as not to form a loop. Dave "Dave" wrote in message ... So, a matching transformer is all I need? I have pretty much decided to use 300 ohm twinlead along the rood ridge with a 300/75 ohm matching transformer to connect it to the coax, and more as needed between the coax and radio. Will that honestly work? Thanks, Dave "starman" wrote in message ... It's an impedance matching transformer or unun. I use the word 'balun' because most people haven't heard the term 'unun'. CW wrote: The word balun to describe this device, while quite common, is incorrect. Go he www.kc7nod.20m.com Look for matching transformer. "Dave" wrote in message ... Away from the house is not possible. Even if it was, that would put it near the power lines. How would I build a balun? (Websites/links?) -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Dave wrote:
So, a matching transformer is all I need? I have pretty much decided to use 300 ohm twinlead along the rood ridge with a 300/75 ohm matching transformer to connect it to the coax, and more as needed between the coax and radio. Will that honestly work? Thanks, Dave A 300/50 ohm transformer is the most common type for a shortwave folded dipole. You can still use 75-ohm coax to the 50-ohm side of the transformer. There would be a slight impedance mismatch but it's not that important for a receiving antenna. I do not recommend using a 300/75 TV balun for this purpose because it's designed to operate at much higher frequencies than shortwave. Remember that you *must* connect the two wires in the ends of the twinlead together to make a folded dipole. Otherwise the high impedance side of the matching transformer (300-ohms) won't be the right value for the antenna. Finally, don't expect this antenna to be great for all shortwave frequencies and directions. We discussed why this is so in an earlier exchange. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
STARMAN,
Why Use a TV type 300 to 75 Ohm Matching Transformer with your SWL Antenna and 'portable AM/FM/Shortwave Radio. May I interject my opinion based on some simple observations using both SWL/HAM Matching Transformers and the cheap TV type 300 to 75 Ohm Matching Transformers. ABOUT - The TV type 300 to 75 Ohm Matching Transformers a * Easy to Find. {RadioShack, WalMart, Walgreens, Kragens, etc} * Simple to Use. {How To - Hook-Em-Up is Self-Evident} * Low Cost. {Under $5} * Generally Functions well and Operates down to 5 MHz and well above 30 MHz. (Most of the better quality ones are now "Marked" for 5 MHz and up.) * Provides Coverage of 'most' of the International Shortwave Bands: 60M, 49M, 41M, 31M, 25M, 21M, 19M, 16M, 13M, and 11M. (But not 90M and 75M Bands) * Plus 'helps' to "Attenuate" Strong AM/MW Signals that create images in the Shortwave Bands. {This is an Important Bonus.} * Allows the 'direct' Connection "Hook-Up" of Low Cost 75 Ohm TV type Coax Cable as an antenna Lead-in-Line. IMHO: For most/many 'portable' AM/FM/Shortwave Radios using a TV type 300 to 75 Ohm Matching Transformer is a very good alternative to a SWL/HAM Matching Transformer. [ Value and Cost ] iane ~ RHF .. .. = = = starman wrote in message = = = ... Dave wrote: So, a matching transformer is all I need? I have pretty much decided to use 300 ohm twinlead along the rood ridge with a 300/75 ohm matching transformer to connect it to the coax, and more as needed between the coax and radio. Will that honestly work? Thanks, Dave A 300/50 ohm transformer is the most common type for a shortwave folded dipole. You can still use 75-ohm coax to the 50-ohm side of the transformer. There would be a slight impedance mismatch but it's not that important for a receiving antenna. I do not recommend using a 300/75 TV balun for this purpose because it's designed to operate at much higher frequencies than shortwave. Remember that you *must* connect the two wires in the ends of the twinlead together to make a folded dipole. Otherwise the high impedance side of the matching transformer (300-ohms) won't be the right value for the antenna. Finally, don't expect this antenna to be great for all shortwave frequencies and directions. We discussed why this is so in an earlier exchange. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Starman,
I am no longer intending to use a folded dipole, or a dipole of any kind. I am currently planning to connect the conductors at the far end of the 300 ohm twinlead but only connect one side of the near end to the 300/75 ohm matching transformer. Will this not work? I don't need perfection, just reasonably good (I think.) Thanks, Dave "starman" wrote in message ... Dave wrote: So, a matching transformer is all I need? I have pretty much decided to use 300 ohm twinlead along the rood ridge with a 300/75 ohm matching transformer to connect it to the coax, and more as needed between the coax and radio. Will that honestly work? Thanks, Dave A 300/50 ohm transformer is the most common type for a shortwave folded dipole. You can still use 75-ohm coax to the 50-ohm side of the transformer. There would be a slight impedance mismatch but it's not that important for a receiving antenna. I do not recommend using a 300/75 TV balun for this purpose because it's designed to operate at much higher frequencies than shortwave. Remember that you *must* connect the two wires in the ends of the twinlead together to make a folded dipole. Otherwise the high impedance side of the matching transformer (300-ohms) won't be the right value for the antenna. Finally, don't expect this antenna to be great for all shortwave frequencies and directions. We discussed why this is so in an earlier exchange. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Dave wrote:
Starman, I am no longer intending to use a folded dipole, or a dipole of any kind. I am currently planning to connect the conductors at the far end of the 300 ohm twinlead but only connect one side of the near end to the 300/75 ohm matching transformer. Will this not work? I don't need perfection, just reasonably good (I think.) Thanks, Dave So you're going to use the twinlead as if it was a single wire. In that case, you might as well connect the two wires in the near end too. There isn't any advantage to keeping the wires of the near end seperated. Connect the twinlead's near end to one wire of the high impedance side (300-ohm) of the matching transformer (balun). The other wire on the 300-ohm side should go to a ground rod, IF you're building the antenna design on the website I gave you. Otherwise connect the remaining 300-ohm wire to the shield of the coax. This will require some kind of adapter, if the balun has a threaded female F-connector for the coax on the low impedance side. A standard coax inline grounding adapter (block) would work. These are made for connecting a ground wire to the coax shield in a TV installation. This adapter has a female F-connector on each end and a grounding screw on the outside of the 'block'. Connect the remaining wire on the 300-ohm side to the ground screw on the adapter block. If you use this kind of adapter you will also need another adapter with a male F-connector on each end to connect the ground adapter block to the threaded female side of the balun. You might be able to find a coax grounding adapter which has a male F-connector on one end and a female on the other end, along with the grounding terminal. Then you wouldn't need two adapters. The center wire of the coax goes to the low impedance side of the balun which is the center hole of the threaded female F-connector on the balun. The coax shield connects to the outside threads of that F-connector, which would also go to the ground rod from the grounding adapter, if you're making the website antenna. All of the above assumes you're using a standard TV balun which has a threaded female coax F-connector for the low impedance side and two wires (pigtails) on the high side. You should install a male F-connector on the balun end of the coax. In the previous post I advised against using a TV balun because it will most likely attenuate signals below about 10-Mhz. This means the lower shortwave bands and also the regular AM(MW) band would be somewhat weaker but this might not be a problem, depending on what frequencies/bands you want to hear best. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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