any way to make a coax wire shortwave antenna
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ka3jjz
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I kinda doubt that it would work - but hey, if you've got some coax lying around, go see basprog's website at Low Noise Receive only Coax loops and go for it. The 160 -10 meter vertical coax loop (about 50 foot total length) that he has about 1/3 down the page might work if you could feed it somehow....
Perhaps a much more likely approach would be the The Carpet Loop (via Hard Core DX) Doesn't look all that tough to build, still uses a loop type design and should be able to be fed into the S350 with a clip lead or similar.
73s and GL...Mike
Perhaps a much more likely approach would be the The Carpet Loop (via Hard Core DX) Doesn't look all that tough to build, still uses a loop type design and should be able to be fed into the S350 with a clip lead or similar.
73s and GL...Mike
RevGary
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This has been around since RG59 was first developed... it is 75 ohm cable, so all you need to connect it to the input of your receiver is a TV 300 ohm to 75ohm adaptor...
Depending upon how much room you have INDOORS, take a 25 foot chunk of RG59 TV coax. Determine how much distance you will need from the radio to the ceiling. Lets use 7 feet for that as an example... Measure out 7 feet from one end of the coax and strip off the outer covering the rest of the way - 18 feet in this case. Then, remove the BRAID that is exposed, along the same 18 foot length. Leave the white inner insullator intact over the center conductor. Place a small piece of electrical tape over the area where the 7 foot undisturbed run meets the area where the center insullator is exposed - just to cover the raw ends of the braid. Install an 'F' connector at the end of the 7 foot run and a 300 to 75 matcher. Attach one of the twin lead pigtails to the antenna input on your receiver and the other pigtail to the ground termainal. The coax white center insullator should be run as much north and south as you can make it and can be attached to the ceiling using bulletin board pins. If this will be used in an attic, the same applies. This antenna is not recommended for outdoor use because of grounding/lightning issues that you may not wish to get involved in. This is a quick and temporary INDOOR antenna which will give good performance compared to a sectioned pull out antenna which may come with some receivers. I have used this type periodically for nearly 40 years and they do a good job.
Depending upon how much room you have INDOORS, take a 25 foot chunk of RG59 TV coax. Determine how much distance you will need from the radio to the ceiling. Lets use 7 feet for that as an example... Measure out 7 feet from one end of the coax and strip off the outer covering the rest of the way - 18 feet in this case. Then, remove the BRAID that is exposed, along the same 18 foot length. Leave the white inner insullator intact over the center conductor. Place a small piece of electrical tape over the area where the 7 foot undisturbed run meets the area where the center insullator is exposed - just to cover the raw ends of the braid. Install an 'F' connector at the end of the 7 foot run and a 300 to 75 matcher. Attach one of the twin lead pigtails to the antenna input on your receiver and the other pigtail to the ground termainal. The coax white center insullator should be run as much north and south as you can make it and can be attached to the ceiling using bulletin board pins. If this will be used in an attic, the same applies. This antenna is not recommended for outdoor use because of grounding/lightning issues that you may not wish to get involved in. This is a quick and temporary INDOOR antenna which will give good performance compared to a sectioned pull out antenna which may come with some receivers. I have used this type periodically for nearly 40 years and they do a good job.
ka3jjz
Wiki Admin Emeritus
A 'snake' - which is what RevGary is describing - is a good choice for desktop radios, but I have my doubts about using it with a portable like the S350. Still it's a cheap experiment ... nothing ventured, nothing gained after all
It's just possible that it might work OK if you just connect the center conductor to the radio, and omit the 300/75 ohm transformer. The S350 would probably need a high impedance unbalanced load, not a balanced 75 ohm load. It won't hurt anything to try... 73s Mike
It's just possible that it might work OK if you just connect the center conductor to the radio, and omit the 300/75 ohm transformer. The S350 would probably need a high impedance unbalanced load, not a balanced 75 ohm load. It won't hurt anything to try... 73s Mike
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Al42
Member
Since an 18 foot wire is nowhere near 75 ohms at almost any frequency, why bother with a transformer? The receiving end of the coax won't be 75 ohms, except at 2 or 3 frequencies.(I'll leave figuring out the 3 frequencies as an exercise for the reader - and, Warren, no fair giving the answers away.) The cable, with no transformer, is actually matched better to any receiver, needing any impedance, at some frequencies than it would be with the transformer.RevGary said:
KC4ZEX
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If the s350 is like most other recent receivers the grundig 400 and sangean ATS models it uses a 1/8 inch mini plug for the external antenna. I recently built a couple indoor antennas and they do a fairly good job, much better than the little 4 ft yoyo type they sell. Take 8 ft or so of RG58 Solder the mini plug on one end center to center, shield to outside shell of plug. Strip back a half or 3/4 in of other end of coax. take 12 or 14 ft of 16 gauge primary or a piece of clear stereo speaker wire pulled apart and solder to center of coax. If you want a dipole use another piece soldered to the ground braid. tape over the connections run along the ceiling in oposite directions. Does a good job from 160 to 10 meters on a Sangean ATS818 or a YB 400 grundig.
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