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Problem With Dipole

D

Djarum

Member
Sep 30, 2008
4
0
11
Hey folks, I'm new to SW and trying to get an Rx antenna set up.

Here's my problem: I'm working with a cheap Grundig GS350, which only has one screw-in type bare-wire input in the back for what it says is a "SW Input" (For a longwire I guess) and a ground. Problem is from all the plans I've seen for dipoles, they're connected to the reciever via a coax which obviously carries two conductors, each connected to one side of the antenna, and I don't know where to connect them considering there's only one SW input.

Does anyone know what I'm to do in this situation? There's some sort of threadless coax-looking input on the back too, but it's labeled as an input for an FM antenna, not a SW.
 

Yeah with the SW radio all you need is a single wire for an antenna. It's been awhile since I have done that but I think the longer the better and you just need small gage.
 
I know the G5RV works great for monitoring as it also works great for transmitting There are also formilas for making inexspensive longwires and parts can be bought at radio shack you can most likely get directions right online if you do a search. does you reciecer have a SO-239 or standard coax hook up on back?
 
Simply cut the end off the cable and separate the inner conductor from the shield. The inner conductor goes to the antenna connector and the shield goes to the ground terminal.If you do not want to cut the connector off then make up a short pigtail and use an inline connector.
 
There you go as QRN said you can make a jumper or pigtail that way your original cable can stay intact and unmodified (y)
 
QRN said:
Simply cut the end off the cable and separate the inner conductor from the shield. The inner conductor goes to the antenna connector and the shield goes to the ground terminal.If you do not want to cut the connector off then make up a short pigtail and use an inline connector.
Click to expand...

Wouldn't this mean that one side of the dipole is the ground then? I didn't know it worked that way, but I will try it as you've instructed. Thank you.
 
The meaning of "ground" can get a bit confusing when dealing with radios. RF is alternating current so has a (+) positive half cycle and a (-) negative half cycle. One half of an antenna is commonly referred to as the "hot" side, the radiating element, and the other half as 'ground'. But the thing is, since RF is alternating current, those 'halfs' switch polarity every cycle or hertz. So, the one called 'ground' becomes the 'hot' side and the 'hot' side becomes 'ground'. Confused yet?
It really makes no difference which terminal either of the conductors in a feed line are connected to (+) or (-). Common convention is that the center conductor of coax goes to the (+) terminal, the braid goes to the (-) terminal. But since the polarity changes every half cycle, the (-) becomes (+) and the (+) becomes (-), so where they start out makes no big deal at all. It's just a convenient way of referring to the poles of an antenna. Those 'hot' and 'ground' thingys make a big difference with DC but not necessarily with AC and/or RF. Don't worry about it a whole lot with antennas.
- 'Doc
 
W5LZ said:
The meaning of "ground" can get a bit confusing when dealing with radios. RF is alternating current so has a (+) positive half cycle and a (-) negative half cycle. One half of an antenna is commonly referred to as the "hot" side, the radiating element, and the other half as 'ground'. But the thing is, since RF is alternating current, those 'halfs' switch polarity every cycle or hertz. So, the one called 'ground' becomes the 'hot' side and the 'hot' side becomes 'ground'. Confused yet?
It really makes no difference which terminal either of the conductors in a feed line are connected to (+) or (-). Common convention is that the center conductor of coax goes to the (+) terminal, the braid goes to the (-) terminal. But since the polarity changes every half cycle, the (-) becomes (+) and the (+) becomes (-), so where they start out makes no big deal at all. It's just a convenient way of referring to the poles of an antenna. Those 'hot' and 'ground' thingys make a big difference with DC but not necessarily with AC and/or RF. Don't worry about it a whole lot with antennas.
- 'Doc
Click to expand...
That explanation helps, thank you.
 
I hooked a long length of speaker wire (100') to a SW radio and had good results.

I just tied a weight to it and tossed it as far up a tree as i could.
 
74IN said:
I hooked a long length of speaker wire (100') to a SW radio and had good results.

I just tied a weight to it and tossed it as far up a tree as i could.
Click to expand...

thats EXACTLY what i did with my grundig S350DL AND my hallicrafters s-40B....

its all you really need for SWL

i did however build a fullwave dipole for FM broadcast band for my grundig

scott
 
What I would do if I wanted to use a dipole or any other doublet type antenna with that radio would be to use 450 ohm twin lead to feed it, and connect one lead to the antenna terminal on the 350, and the other to the ground terminal. I'll bet you could use just about anything and get good results. 300 ohm twinlead, 75 ohm coax, 50 ohm coax. We're talking SWL here, not transmitting HF.
 

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