Well I use a Tennadyne T8 for 13.5 to 30 MHz. It is a 6 meter [18 feet]
boom. I am not familiar with the ATN 18-30-7 LP.

But, LP design is based upon a specific ratio for adjacent lengths and
element spacing. So, just 'fiddling' with adding elements and adjusting
spacing gets to be serious business. You will have to re-space ALL
elements on the boom, and increase the length of ALL the elements to
achieve the desired ratios.

The ARRL Antenna Handbook has an excellent section on LPs. Buy or borrow
a copy and read up on LPs. It's quite a project!

Deacon Dave, W1MCE
+ + +
TS wrote:
Hi all

Was wondering if there is anyone out there who can help? I have just
purchased a 7 element ATN 18-30-7 log periodic that covers 18-30Mhz. I
believe there is another ATN aerial with the same boom length of 6 metres
that covers 14-30Mhz. I was hoping someone with one of these beasts could
advise the element lengths etc so i can convert mine to cover 20metres. I
assume i will need to rearrange the elements, drill alternate mounting holes
and change some element lengths and make some crossover straps for phasing
harnesses but thats just a formality. My aerial comes with a diagram of the
element lengths etc so was hoping someone could scan and send. I could start
from scratch and try and design a unit but this would save me a heap of
time. It appears that ATN is long gone. Any help would be greatly
appreciated. I have quite a collection of amateur radio related service
manuals in pdf and or jpg format so maybe i can return the favour.

email for reference is

Thanks in advance.
Cheers
Tony
VK2TS