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I'm trying to get into backpacking QRP, which has lead me to read up on various ways to construct very portable wire antennas. I would ideally like to have a single antenna for the CW parts of the 40, 30 and 20 m bands, while avoiding having to bring a general purpose tuner.

There are various options, but one that caught my eye and which I want this question to be about is the use of crocodile clips to simply disconnect parts of the wire. Using my current needs as an example, an end fed wire around 20 meter long could thus work as half wave on 40 m and as a full wave on 20 m, and if I want to work 30 m I just disconnect 5 meter at the end to get a half wave once again. Perhaps I could even put a pair of clips in the middle as well if I want a half wave antenna for 10 m as well(?) I don't want to get the question too stuck on this precise design though, but keep the focus on the technique itself.

My main question is: Are there any downsides to using crocodile clips to change the length of the antenna? (or even to change its topology?) Is there anything special I need to keep in mind if I go with this approach?

I could see how this could be less appropriate if you plan to transmit several hundred Watts, but I'm thinking QRP.

I imagine it might be hard to get the connection good enough in terms of resistance. Also, the resistance of the clips themselves, being different from the wire, might be a problem. I've tried using a search engine, but it's hard to separate pages where crocodile clips are discussed from those where they are simply used in experiments.

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  • $\begingroup$ Hello Edvin, and welcome to ham.stackexchange.com! $\endgroup$
    – rclocher3
    Mar 15 at 16:55
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If you look up "link dipole" or "linked dipole" you will find several designs that do just that. It works well for QRP or even for 100W. The ones I've seen have used several different connectors: alligator clips, quick disconnect spade terminals, Anderson PowerPoles, and banana plugs, to name a few. Of those, alligator clips are probably my least favorite in terms of reliability, and banana plugs or PowerPoles my favorite, providing an easy and low-resistance connection. But pick anything you have on hand and it will probably work alright. Just make sure to provide some strain relief so that any tension in the wire isn't carried by the connectors.

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  • $\begingroup$ I've seen them being called that, and it can't be too bad as people are using it. I still would like to know more about how (or if) dividing the wire into segments like this affects performance. Should I read your post as saying it doesn't? $\endgroup$
    – EdvinW
    Mar 11 at 8:43
  • $\begingroup$ @EdvinW-SM4YPU yes. It doesn't have any significant effect. The connectors are small compared to HF wavelengths, and a good connection doesn't add enough resistance to matter. $\endgroup$ Mar 12 at 2:55
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    $\begingroup$ As suggested, I think the biggest danger is reliability. the big disadvantages are corrosion, fatigue, and sudden disconnections. If you inspect for and try to prevent those things, it's probably all good. $\endgroup$
    – user10489
    Mar 14 at 6:11

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