END FED QUESTIONS ..

VanRougeT4 wrote:

@Bass 666

I've recently been looking into end fed antennas, and am at the moment constructing one for temporary use. There's a very useful site that I will link to below.

As I understand it, you can create a 'random' wire multiband end fed that uses a 9:1 unun. The wire isn't actually random though. What you must do is avoid half wave lengths for each of the bands you want to use, that makes the impedance at the fed end about 450 ohms. A 9:1 unun will bring that down to a usable 70 ish ohms on all the bands you want to use. That's within the range of any antenna tuner/matcher.

You can avoid electrically earthing the coax by having a counterpoise.

For 40 20 & 10 I'm going to start with an end fed length of 41 feet. If that doesn't work too well I'll shorten to 35.5 feet.

Hope this helps.

Deb

https://www.hamuniverse.com/randomwireantennalengths.html

thanks for the reply .. yeah i have been watching loads of youtube vids on 41 foot wires and they are all fairly good .. 
the counterpoise problem for me as i have read is ok because the coax i use to get to the unun is so long it will act as the earth .. a 1-1 balun is needed for rfi but it seems there are conflicting stories about where it is placed .. some say at the back of the radio and others say just before the unun ? more homework needed ..

BASS 666 wrote:

Quote :

the counterpoise problem for me as i have read is ok because the coax i use to get to the unun is so long it will act as the earth .. a 1-1 balun is needed for rfi but it seems there are conflicting stories about where it is placed .. some say at the back of the radio and others say just before the unun ? more homework needed ..

VanRougeT4 wrote:

BASS 666 wrote:

Quote :

the counterpoise problem for me as i have read is ok because the coax i use to get to the unun is so long it will act as the earth .. a 1-1 balun is needed for rfi but it seems there are conflicting stories about where it is placed .. some say at the back of the radio and others say just before the unun ? more homework needed ..

I would lay out a 17 foot counterpoise and wind 6 turns of 6 inch diameter in the coax close to the radio. If that doesn't work for you, put a 1:1 balun somewhere in the line. Easy to experiment position; either at the antenna end of the coax or near the rig. But you may find, if all is constructed carefully and with a counterpoise, that you don't need the 1:1 balun.

Deb

yeah iv seen the guys doing it with and without the counterpoise .. like you say it's easy doing it both ways to see whats what ..

VanRougeT4 wrote:

BASS 666 wrote:

Quote :

the counterpoise problem for me as i have read is ok because the coax i use to get to the unun is so long it will act as the earth .. a 1-1 balun is needed for rfi but it seems there are conflicting stories about where it is placed .. some say at the back of the radio and others say just before the unun ? more homework needed ..

I would lay out a 17 foot counterpoise and wind 6 turns of 6 inch diameter in the coax close to the radio. If that doesn't work for you, put a 1:1 balun somewhere in the line. Easy to experiment position; either at the antenna end of the coax or near the rig. But you may find, if all is constructed carefully and with a counterpoise, that you don't need the 1:1 balun.

Deb

BASS 666 wrote:

if i cut 41 foot of wire do i have to allow for looping it round the isolator ? do i cut 41 foot spot on and then loop it round the isolator ?

VanRougeT4 wrote:

BASS 666 wrote:

if i cut 41 foot of wire do i have to allow for looping it round the isolator ? do i cut 41 foot spot on and then loop it round the isolator ?

I intend to cut mine a bit long, say 42 feet, then trim or fold back for best vswr.

Deb

PS. We'll be in Belfast in May (round Ireland campervan trip) visiting the Titanic experience. Maybe catch you on 11m.

 40/20/15/10 

Purple Witch wrote:

Have you room for, or considered using an inverted V dipole? Maybe something like a half size G5RV. You have the height for it. It should be good for 40-10m and it's cheap to buy or even cheaper to make. I run one and I also slope it an 45degrees to get extra directional lift. i have it tuned in best from 10-20m but it'll match in up to 40m with not much effort.

BASS 666 wrote:

VanRougeT4 wrote:

BASS 666 wrote:

if i cut 41 foot of wire do i have to allow for looping it round the isolator ? do i cut 41 foot spot on and then loop it round the isolator ?

I intend to cut mine a bit long, say 42 feet, then trim or fold back for best vswr.

Deb