Longwire antenna

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greedo24

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Hello all:

I just repurposed about 100' of speaker wire to be my longwire antenna for my shortwave radio. Naturally I separated the twin wires so I am only use one wire and not a pair. Question, though, Is there any sort of grounding I should do with this antenna, or should I just hook one end of the longwire right up to the antenna input of my set?

Thanks!

-Greedo
 

w2xq

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There is not enough info to properly answer the question. What is the radio? But there are some general statements previously discussed in threads here. Search is your friend. A few:

If you are using a portable radio, a wire of that length may gather enough strong signals as to overload the radio and induce spurious images. Generally, I wouldn't use anything longer than ~15 feet unless I was in a low-signal area of the country. Variables: population density, noise sources, proximity to AM broadcast towers, proximity to power lines, terrain and more.

If a longer wire is outside, I would be concerned with static buildup from atmospheric sources, eg, thunderstorms and snow. Static can pop the radio's front end. Depending on the type of the radio and the height of the antenna compared to nearby higher objects (trees, for example), precautions could be taken.

A ground may or may not help, again depending upon whether the radio is a portable or a communications tabletop radio. For example, I probably wouldn't bother using a ground wire with a portable radio and a short wire. But then I wouldn't leave the portable connected to the longer wire unless I needed it.

YMMV. Do search through the forum messages and wiki as there are many ideas discussed here. HTH a bit.
 

Boombox

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What the above poster said is good advice.

If you live in a low signal area, 100 ft. may help. I live in a low signal area, and I was able to use a 100 ft wire with my DX-390 (which is a digital portable), and got good results, with minimal spurious images.

However, if you live in a high signal area, a longer wire could overload your radio, unless you have a tabletop SW set (like a Kenwood, Drake, etc.).

If you're not sure, maybe try the 100 ft wire, and then keep shortening it until you get better results. If you're getting spurious images, you'll soon know. They will be SW broadcast stations around 1 Mhz lower than they should be (I.e., you get SW Broadcast signals in the 8 Mhz portion of the SW band, when they really are transmitting in the 9 Mhz SW band (the 31 meter band).

Some radios are more prone to images than others. I sometimes get a couple even with a 25 ft wire on one of my radios, and I just ignore them, because usually they fall outside the SW broadcast bands on my radios. But it's something to be aware of.

As far as a ground goes.... although others swear by them, I've never had any improvement using a ground with an antenna.
 

SpectreOZ

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As far as a ground goes.... although others swear by them, I've never had any improvement using a ground with an antenna.

I've had mixed results myself... AM BCB definitely benefits from a grounded antenna system whereas SW is reasonably indifferent (I have seen some reduction in interference on the odd occasion), LW can go either way increasing signals (or not) but definitely increasing band noise reception without a ground.
 

w2xq

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Until Greedo24 gives us more info on the radio and environment, there's not much more that can be said.

For about 10 years I had a 1000 foot Beverage running NE hooked to a JRC NRD-525 but things got a bit difficult when the local 640 station went to 50kw day. Six miles from the 4 - tower array, in the main lobe, a VOM showed a significant voltage flowing on the antenna. Using a notch filter I knocked the signal down from 90 to 50 dB over s9, good enough to let the receiver behave properly.

An easy way for here to check portable radio signal overloading was to look above WWV 5 MHz. The strong 49m RCI Sackville, NB, relay signals were a dead giveaway.

So Greedo24, wassup?
 

k9rzz

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Just a word of experience when using speaker wire as antennas. Over time (months/years), oxidation of each strand works it way up the wire from the ends and that may induce AM broadcast splatter across the HF spectrum, especially if you have any transmitters nearby. I've never had any problem with stranded house wiring, just speaker wire. FWIW
 

LtDoc

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Stranded wire does oxidize and can cause noise, but it doesn't 'induce' any sort of AM broadcast splatter across the HF spectrum. That oxidation results in a 'bi-metal' produced interference. That interference isn't limited to any portion of the RF spectrum, it can affect all of it. One easy way to limit how much of that interference is produced is to use insulated wire. That oxidation isn't instantaneous, it takes a while to happen, and that time span doesn't have to be any certain length, months to lots of years. In general, it just isn't something to worry much about, it just isn't a biggy.
- 'Doc

And while I'm at it, a classic "longwire" antenna is one that is a minimum of 2 wave lengths long at it's design frequency. Most of the so called 'longwire' antennas are actually 'random length' antennas, less than two wave lengths long at the frequency of use.
 
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k9rzz

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Stranded wire does oxidize and can cause noise, but it doesn't 'induce' any sort of AM broadcast splatter across the HF spectrum. That oxidation results in a 'bi-metal' produced interference. That interference isn't limited to any portion of the RF spectrum, it can affect all of it. One easy way to limit how much of that interference is produced is to use insulated wire. That oxidation isn't instantaneous, it takes a while to happen, and that time span doesn't have to be any certain length, months to lots of years. In general, it just isn't something to worry much about, it just isn't a biggy.
- 'Doc

And while I'm at it, a classic "longwire" antenna is one that is a minimum of 2 wave lengths long at it's design frequency. Most of the so called 'longwire' antennas are actually 'random length' antennas, less than two wave lengths long at the frequency of use.
It IS a biggy when you're using older wire with oxidation (even insulated) and your local AM radio stations (because they are close to you and LOUD) are splattering all over HF and you're pulling your hair out ... WHAT HAPPENED?.

I'm just relaying personal experience to help someone else down the road. Whether you choose to believe it is up to you. Happy DXing! (as you listen to "boots and pants, boots and pants, boots and pants" all over 40 meters)
 

greedo24

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Thanks for the info so far. You're right- I should have provided more info. My radio is a portable battery operated SONY ICF-SW7600GR. I live in an area that is sort of like a suburb. Not too heavily populated. Nearest high tension line is over a mile away from me. The terrain is relatively flat (I live in the Holland/Zeeland area of Michigan). The radio came with a 15-foot yo-yo antenna that I can clip onto the areal but from what I've read a longer wire can give you even better results. I also have a 3-foot diameter mag loop antenna that I could use, and some have said this would be even better because it will pick up less electrical static.
 

LtDoc

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K9RZZ,
Sorry, but you are talking about a matter of 'degree'. It's certainly possible for a stranded conductor to produce un-wanted noise at some particular frequency, but if you take 'reasonable' precautions, the 'possibility' is minimized to a great extent. There ain't no 'absolutes'! You can NOT compensate for everything! If you expect absolute the best reception at all frequencies all of the time... can I interest you in buying a huge passenger ship that hasn't been moved in years??? It's called the 'Queen Mary'. Do I own it? Uh... you bet! Wanna buy it??
- 'Doc
 

k9rzz

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Maybe my point got mixed up ... I have had bad experiences using speaker wire for antennas in the past. I would avoid it. My .2 cents - That is all. 73!
 

w2xq

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I also have the ICF-7600GR, IMHO probably still one of the best portables in the market today. My http://www.mwcircle.org/mw_rec_sw7600gr.htm review is still online. I haven't found something newer that I would rather have.

Frankly, I don't find a need for an external antenna unless I am in a building with steel construction (think hotel), then I will drape that roll up antenna at a window. Otherwise, I'll use the wire during the day to help with weaker signals like All India Radio (11620 as I recall) to Europe. At night, I find I don't need the external antenna.

You have a good radio. It's not for me to say that a 100' wire wouldn't help, but I would be surprised if that amount of wire would be necessary. And you shouldn't need a ground. Just don't tempt fate with thunderstorms or leave that long wire connected when not listening.

YMMV. HTH.
 
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greedo24

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Hey thanks, trsundstrom! Sounds like it's mostly a matter of experimentation to see if I can do better than just the whip. Which I can do, in time. Meanwhile, I'll see what all I can pull in without any external antennas as a benchmark. I'll let you know what results I come up with. And I'm headed over to read your review on this little radio right now. *hat tip* Good day, sir.
 

LtDoc

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The only place I would remove insulation is where I was going to make an electrical contact. That insulation isn't going to be a concern so why bother about removing it. Get pink insulation! Makes electrons curious and they get caught faster/easier...
- 'Doc

If you believe that about the 'pink'... I got this boat for sale!
 

E-Man

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Thanks for the info so far. You're right- I should have provided more info. My radio is a portable battery operated SONY ICF-SW7600GR. I live in an area that is sort of like a suburb. Not too heavily populated. Nearest high tension line is over a mile away from me. The terrain is relatively flat (I live in the Holland/Zeeland area of Michigan). The radio came with a 15-foot yo-yo antenna that I can clip onto the areal but from what I've read a longer wire can give you even better results. I also have a 3-foot diameter mag loop antenna that I could use, and some have said this would be even better because it will pick up less electrical static.
Just a FYI if you are not already aware.

Pg 35 of the Owners Manual states:

Do not connect external antennas other than those recommended to
the AM EXT ANT jack. This jack outputs DC voltage for antenna
power supply.
 

SCPD

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phil418

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Long wire with Sony 7600

I am currently using a longwire plugged in the ext antenna of the sony 7600gr. Reception is improved quite a bit compared to the reel antenna, however I need to push the plug only halfway into the radio, reception is not very good if pushed all the way in. I am using a coaxial to mini as the piece that goes into the ext antenna, any idea how I could fix this as I am afraid I will damage the radio antenna jack if i leave the connector halfway in all the time. Thanks
 
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