Home |
Search |
Today's Posts |
|
#1
|
|||
|
|||
"RHF" wrote in message om... DAVE, At the Radio-End of the 75 Ohm Coax Cable "F" Connector you can use a standard 75-300 Ohm Matching Transformer and then connect it to a Mini-TV External Antenna Adapter. [ RadioShack {Canada} Catalog #: 15-1148 = 75 to 300 Ohm Mini-Plug Adapter ] MINI-PLUG-ADAPTER= http://tinyurl.com/23nsh FWIW: Some RadioShacks and other electronics stores have an "Adapter" that directly connects an "F" Connector to a /18" Mono-Phone-Jack. Please Note: That a 'connection' to a good earthen Ground is needed to one of the "F" Connectors of the 75 Ohm Coax Cable. You can use a #14 Wire with a RadioShack Catalog #: 278-002 Heavy-Duty Claw Insulated Test/Jumper Cable Sets. Or, simply use several windings of bare wire wrapped around one of the "F" Connectors with a small metal hose clamp to secure the wire. iane ~ RHF . . = = = "Dave" wrote in message = = = ... Just printed your instructions in prep for a trip to the store, and have one question: The twin-lead is 300 ohm, connected to a 300/75 ohm matching transformer, connected to 75 ohm coax. Then the coax is connectect to another 75/300 ohm matching transformer, which is connected to the 1/8" mono plug to plug into the external antenna jack? Is the 1/8" jack a 300 ohm impedance connection? Somehow I thought it would be 50 or 75 ohms, like coax. Do I need some 300 ohm coax to put between the second transformer and the plug? Thanks, Dave "RHF" wrote in message om... DAVE, So you have a Sangean ATS -505 and your 'problems' are Antenna Overload and Noise Levels. * Consider a 'smaller' shorter Antenna will reduce the overload problems. * Consider a Low Noise Antenna Design will reduce the noise problems. {LOW NOISE SWL ANTENNA - popularized by John Doty} http://groups.yahoo.com/group/Shortw...enna/message/2 http://www.anarc.org/naswa/badx/ante...e_antenna.html For a simple 'external' Shortwave Antenna to use with the Sangean ATS-505 'portable' Shortwave Radio, using the 1/8" Mono-Jack External Shortwave Antenna Input. Consider a Random Wire Antenna using a Matching Transformer and Ground for Low Noise and Wide Range Frequency Coverage. PARTS: Here is a simple SWL Antenna Idea using a few common RadioShack TV Antenna type parts: Catalog #: 15-1174 = 25~50 Foot 300 Ohm (Flat) TV Twin-Lead Catalog #: 15-1230 = 75 to 300 Ohm Matching Transformer (2 Ea.) Catalog #: 274-286 = 1/8" Mono (Phone) Plug Catalog #: Catalog #: 15-1579 = 25~50 Foot Coax Cable with F Connectors NOTE: This is an 'improved' Random Wire SWL Antenna using "TV" Parts for 'reducing' Man Made Noise (RFI EMF) that is generated in or near most modern homes/buildings. EXTERNAL "OUTSIDE" SWL ANTENNA: The Antenna [Loop] Element is Stretched outside Horizontally or in the shape of an Inverted "L". The Antenna [Loop] Element is formed by connecting the two ends of the Far-End of the 300 Ohm TV Twin Lead. This forms a continuous single skinny horizontal flat loop going out and back. This also represents a Balance 300 Ohm Load to match-up with the 300 Ohm Matching Transformer. The 300 Ohm Leads of the Matching Transformer connects to the Near-Ends of the Loop Antenna Element. The 75 Ohm F Connector of the Matching Transformer is connected to the 75 Ohm Coax Cable. The 75 Ohm Coax Cable acts as the Lead-In from the Outside to inside the house to the radio shack. The other end of the 75 Ohm Coax Cable is connected to the 75 Ohm F Connector of the Matching Transformer. The Radio-End of the Coax Cable F Connector would connect to a 75 to 300 Ohm Matching Transformer; and then into a 1/8" Mono-Plug to plug into the Radio. NOTE: Using the 300 Ohm TV Twin Lead in a Skinny Flat Loop Antenna should balance-cancel-reduce most man made noise and be Omni-Directional. GROUND: Find a Grounding Point within/about your dwelling. Secure a good Grounding Point for your Radio and Antenna. Run a Heavy & Short Ground Wire to your Radio. Locate the Ground Terminal on your Radio. Attach/Secure the Ground Wire to the Coax Cable and/or the Radio's Ground Terminal. FWIW: This Antenna using common TV Antenna type parts should be effective as SWL Antennas above 5MHz and beyond 30MHz. iane ~ RHF . Some Say: On A Clear Day You Can See Forever. http://groups.yahoo.com/group/Shortw...na/message/502 I BELIEVE: On A Clear Night... You Can Hear Forever and Beyond - The Beyond ! . . = = = "Dave" wrote in message = = = ... I recently hooked up a thirty-six foot (plus or minus a couple of feet) piece of four-stranded wire with alligator clip to the internal "whip" antenna of my portable shortwave receiver, for the extra performance such a device offered. It works so well that I now cannot usually use my "DX" setting because of all the background noise (sounds like hundreds of other broadcasts vying for attention.) I don't know the frequency source of all this background noise, but would like to filter out as much of it as I can. One manufacturer of a similar "wind-up" antenna adds a capacitor to the wire in order to lower the resonance frequency of the wire. If I were going to try something similar (adding a capacitor, in series) in an attempt to bring the resonance of the wire down into the 30 MHz range, what size (roughly) capacitor should I use? Should I just try a few with different ranges, or does anyone here have any suggestions? TIA Cross-posted between sci.electronics.basics and rec.radio.shortwave Dave . |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Antenna feed wire question | Antenna | |||
Long Wire Antenna Question | Shortwave | |||
Long Wire Antenna Question | Shortwave | |||
Long Wire Antenna Question | Shortwave | |||
Balun | Shortwave |