Another quick one for you folks, i am trying to resonate my inverted L antenna for 40 & 80m the 40m side of tha antenna was bang on at 7.1mhz with a SWR reading of 1.3.1 done something right however the 80m part of the antenna is 3.1.1 @ 3.582mhz and at the top end of the band it's 7.1.1 @3.80mhz am i right in thinking the 80m part of the antenna is too long and needs trimming or is it the other way round and needs more wire added to it.

It is fed against ground with the braid of the coax attached to the copper pipe and the centre of the coax connected to the antenna wire.

I would like to get it sorted out before i add the 80m trap so i can use it on top band 1.9mhz
what are the chances of me pruning the antenna and have to do it again when i add the 3.5mhz trap??
cheers Keith

Keith,

Yes it's too long - you need to trim some off the extension beyond the trap. Take it in small bites

73,
Steve G3TXQ

Thank you Steve
73

Is that literally just a piece of pipe knocked into the ground?
I'd have thought more than that was needed?
Just a non HF user observing from the sidelines.

Cheers

Tony

If you've started off with measurements for an inverted L on the lowest band, multi-banding it by adding traps results in the overall wire lengths needing shortened due the extra loading produced by the traps themselves.

It will probably require a more extensive ground system to make it efficient.

Hi Tony it's a 4ft copper pipe and about 10 1/4 wave radials spread out under the gravel in my garden
seems to work OK for me

Ah!
Radials.
Just thought I'd mention as I have come across someone who just put a lightning rod down and thought it would be fine.

Cheers

Tony

All sorted now managed to get the SWR down to 1.2.1 @ 3.775 just where i wanted it
now let's see what happens when i add the 3.5 trap in the mix

You say 3 band Inverted L Keith , is it the Battle Creek Special you've gone for?

The GM0ONX inverted L works well here, have a couple of radials out, but not easy as tother half
doesnt like wire all over the place.
1 trap to give me 80metres, even works on 6metres.

Phil

Hi Keith your trap is ready by the way can you pm me your address please so I can post it for you tomorrow.

All the best from Mark 2w0jmk

BONNY LAD.
MY ANTENNA IS BASED ON GM0ONX DESIGN AND WORKS GREAT AND I GOT THE TRAPS FROM THE SAME SOURCE AS YOU DID THANKS MARK. REMEMBER ONCE YOUVE GOT 40 WORKING GOOD ADD THE EXTRA 6,55 MTRS OF WIRE AND PLACE THE ANALYSER ON IT TUNE FOR RESONANCE ON 80 MTRS ONCE YOUVE 80 MTRS SORTED THEN ADD THE 3.5 MHZ TRAP AND THE EXTRA WIRE ON THE END OF THE 3.5 TRAP MHZ THEN DO THE SAME FOR 160. IM VERY IMPRESSED WITH THE RESULTS IM GETTING IVE GOT ALL BAND COVERAGE NOW 10 TO 160.IVE GOT AN EARTH ROD 5 FOOT LONG AND 10X50 FOOT RADIALS UNDER THE LAWN.. REGARDS DAVE G0AYD..

For those using Len's design, what height is the vertical section on your antennas?

I don't think it's critiacal but for what it's worth i have mine 20ft vertical and the rest running horizontal