EFHW 80M Loading coil

[gmham]

Be interesting to hear your swr measurements on 40-20-15 and 10 mtrs ?

Using the U.K. antennas 40-10 mtrs EFHW myself and well happy with it. Highest swr is on 40 mtrs at around 1.7 but still perfectly acceptable.

[Buick Mackane]

Be interesting to hear your swr measurements on 40-20-15 and 10 mtrs ?

Using the U.K. antennas 40-10 mtrs EFHW myself and well happy with it. Highest swr is on 40 mtrs at around 1.7 but still perfectly acceptable.

Not sure if you mean after the coil has been added, But the current readings are

Mine is a homebrew effort

40m - 1.1 - 1.3
20m -1.5
15m - 1.1 through the entire band
10m around 1.5 on the SSB Portion

[Whisky1]

I got about 500khz usable spread before I needed a tuner, 49/1 with around 60ft of wire then 110 with a tail of around 6 feet.
I was ok with it for the size and whilst it wasn't a dx buster I did work s/america and india on 100 watts at around 40ft L config no radials.

Nothing wrong with 500 khz bandwidth, That's more than the entire 80m band, Suppose it depends on a few factors like height above ground etc

Ha ha sorry wrong about 120khz according to my notes that I've dug out, I tried it at 25ft and the bandwidth shortened slightly.

[Buick Mackane]

I got about 500khz usable spread before I needed a tuner, 49/1 with around 60ft of wire then 110 with a tail of around 6 feet.
I was ok with it for the size and whilst it wasn't a dx buster I did work s/america and india on 100 watts at around 40ft L config no radials.

Nothing wrong with 500 khz bandwidth, That's more than the entire 80m band, Suppose it depends on a few factors like height above ground etc

Ha ha sorry wrong about 120khz according to my notes that I've dug out, I tried it at 25ft and the bandwidth shortened slightly.

Yeah around 100 Khz seems to be the norm for a 110uh coil, You could always go for less inductance and a longer wire after the coil if you have the space, That would give you more bandwidth, Not got mine made up yet as i'm still waiting on the wire to be delivered

[Buick Mackane]

Well that turned out to be a waste of time, Done 72 turns and checked the inductance and it was around 130uh, So took a few turns off and checked it again and it was spot on 110uh, But by the time i had put it all together it had dropped to 98uh for some reason. So i bunged it up and it was resonant around 2.3 Mhz with a bandwidth of roughly 600 KHZ. So took a few turns off but never made much of a difference. Think my inductance meter is flakey, But either way i should have been in the ballpark, My EFHW is only 6m high, So maybe that was detuning it on 80m.

BTW never had any effect on the SWR on 40/20/15/10m

Bit of a head scratcher, I'll go back to it some other time

[Buick Mackane]

All working now

Turns out it's height above ground was detuning it. Last ten feet or so was running down a pole in an inverted vee configuration, Which meant the stub after the coil was only a few feet above ground, Tried another configuration and it now works a treat, 150 Khz of bandwidth on 80m. Coil is only 98 uh so i had to make the stub longer (7 feet) SWR on the other bands is much the same, Infact its reduced my SWR on 10m

Don't expect 80m performance to be anything special, But should be slightly better than an 80m mobile antenna as it has less loading

[Whisky1]

Ah good stuff bud, you got there in the end I still have mine packed up with a few other wires that were worth keeping, I'm currently using a g7fek that is working a treat on 80/40 and other bands with a tuner.
I need to get my 40 meter full wave loop up that was awesome with the the 4/1.
You'll work on 80 ok with that.

[Buick Mackane]

Hard to believe people are paying £25 on ebay for these loading coils, He's sold 85 of them

https://www.ebay.co.uk/itm/265431661816 ... R8a8yu33YQ

Mine was put together for a fiver And i have an inductance meter which obviously helps,

For anybody that's interested the specs of the coil are

55 turns of 0.63mm wire on a 42mm former, Coil length is 40mm inductance 98uh

[Buick Mackane]

It's finally up in it's permanent position. Lowest SWR on 80m is 1.1

Bandwidth 130 khz, 3.650 - 3.780 Khz

[chr0nik]

Would adding one of those coils on both sides of a 40m dipole work? I have a 40m/20m fan dipole and would like to get some of 80m too.

[Buick Mackane]

Would addind one of those coils on both sides of a 40m dipole work? I have a 40m/20m fan dipole and would like to get some of 80m too.

Yes it will work, If you have room for an 80m dipole then you could add traps to get 80m / 40m on the same dipole


Take a look here

https://www.jotrin.com/tool/details/TTXSJJSQ