DIY end-feed antenna for 20m

[Ruso]

Gentlemen,
I might hit a sweet spot with my setting but willing to share really low cost solution (around $80) worked for me.
No fancy ground, no fancy backstay cut antenna, no external tuner - I have IC-737 with built in one.
Materials
1. Wire 12GA
From Amazon https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
2. Rope 50 ft
Samson Amsteel Blue 7/64" 50', 100', 200' or 300' Hanks Coated Blue, Green, Black, Silver, Orange, Red or Yellow dyneema Fiber 1600lb
3. 9:1 UNUN
Got from e-bay but presently out
https://www.ebay.com/itm/303094009549
4. To wrap coax around it right next to radio.FT-240-31 Ferrite Toroid Core - | 31 Material
https://www.amazon.com/dp/B084JQ7ZK3...v_ov_lig_dp_it

Environment
wire 45 feet inserted into dyneema rope going up to mast(with wire inside) and back to Bimini (empty) for tension.
15 feet of coax going to my radio.
Radio Icom IC-737 with built in auto-tuner.
That's it.
Easy contacts 5-6 hundred miles on 20m. Reported very good signal

[Ruso]

Sorry, Gentlemen IT IS 40 METERS!! YES!! 40 METERS

Originally Posted by Ruso

Gentlemen,
I might hit a sweet spot with my setting but willing to share really low cost solution (around $80) worked for me.
No fancy ground, no fancy backstay cut antenna, no external tuner - I have IC-737 with built in one.
Materials
1. Wire 12GA
From Amazon https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
2. Rope 50 ft
Samson Amsteel Blue 7/64" 50', 100', 200' or 300' Hanks Coated Blue, Green, Black, Silver, Orange, Red or Yellow dyneema Fiber 1600lb
3. 9:1 UNUN
Got from e-bay but presently out
https://www.ebay.com/itm/303094009549
4. To wrap coax around it right next to radio.FT-240-31 Ferrite Toroid Core - | 31 Material
https://www.amazon.com/dp/B084JQ7ZK3...v_ov_lig_dp_it

Environment
wire 45 feet inserted into dyneema rope going up to mast(with wire inside) and back to Bimini (empty) for tension.
15 feet of coax going to my radio.
Radio Icom IC-737 with built in auto-tuner.
That's it.
Easy contacts 5-6 hundred miles on 20m. Reported very good signal

[Jim Cate]

^^^^

?????

Jim

[Brian.D]

So your auto tuner in the radio is actually tuning the antenna. OK, yeah, I would say you found a length of wire that will resonate near a working wavelength of wire. If it will resonate with your tuner on 40, then is should work on 20 also. Auto tuners in radio really don't have the means to match wide and wild impedance. So finding a length of wire that has an impedance close to your working frequency was either pure luck, or you mathematically figured it out. Well done.

Now the question is raised, what are you using for a counterpoise? The radio must be "grounded" to something in order for the antenna to "see" an opposing side. Wire antennas must have some kind of counter in order to work correctly. Be in something in the boat or a physical connection to the sea. You really didn't describe that side of the connection.

[Ruso]

Coax from unum to radio acting as counterpoise...this is beauty of it.

[S/V Illusion]

Just about anything can work, the issue is how effectively it radiates with minimal loss which an SWR meter doesn’t provide the whole picture. Example for effect - even a light bulb will load with minimal SWR.

[Brian.D]

Originally Posted by Ruso

Coax from unum to radio acting as counterpoise...this is beauty of it.

I suspected as much since you did not list a Common Mode Choke. But I might recommend a CMChoke right next to the rig's output connector.

[Ruso]

Originally Posted by Brian.D

I suspected as much since you did not list a Common Mode Choke. But I might recommend a CMChoke right next to the rig's output connector.

Thank you. I will research on it. If you can post the source I can buy?

[Brian.D]

There are too many sources. With that in mind, do a search on Common Mode Baluns. You'll probably want one with SO-239 connectors. There are many on EBay. The other option is to make your own. You can also search on DIY Common Mode Balun. You can actually make one out of coax, might be cheaper if you already have the coax.

[Ruso]

Originally Posted by Brian.D

There are too many sources. With that in mind, do a search on Common Mode Baluns. You'll probably want one with SO-239 connectors. There are many on EBay. The other option is to make your own. You can also search on DIY Common Mode Balun. You can actually make one out of coax, might be cheaper if you already have the coax.

Thank you... I wrap coax over Ferrite Toroid Core next to my rig, but it seems not enough but definitely better. Before my led lights in the boat switched ON after transmit. Just ordered LDG tuner with control cable for Icom hoping it will improve SWR... SWR is another problem I have digital MFJ but readings sporadic and hard to understand.

[Stewie12]

A centre fed dipole run up the backstay would be my choice. Simply, cheap and worked well for me.

[Ruso]

Originally Posted by Stewie12

A centre fed dipole run up the backstay would be my choice. Simply, cheap and worked well for me.

Like "Gamma"?)don't remember exact brand name.. slip up around backstay... not cheap. I was concerned that some emission power will destructed by backstay..

[Stewie12]

It worked fine for me during an Atlantic crossing and several year in the Caribbean.

[Catboat Willy]

End fed antennas can be tricky and you've got to be careful you don't put too much voltage on the finals of that Icom-735. You radio's internal antenna is only spec.out match to appx. 150 ohms. There are some lengths of random wire that will work better on various freqs. - (better than others) and some lengths to avoid . Here is a handy guide to what are your best lengths for the ham bands; https://udel.edu/~mm/ham/randomWire/
73's de....W2CWL/MM
QRZ.COM

[Ruso]

Good resource, thank you.. Need to take my antenna down and measure exactly the length. My previous length was 34-36 feet - did not work out...

Originally Posted by Catboat Willy

End fed antennas can be tricky and you've got to be careful you don't put too much voltage on the finals of that Icom-735. You radio's internal antenna is only spec.out match to appx. 150 ohms. There are some lengths of random wire that will work better on various freqs. - (better than others) and some lengths to avoid . Here is a handy guide to what are your best lengths for the ham bands; https://udel.edu/~mm/ham/randomWire/
73's de....W2CWL/MM
QRZ.COM