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

Hello Tony

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.

You might get some help trying this

http://www.fortunecity.com/skyscrape...5/LogCalc.html

Regards Max

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

Dear Tony (VK2TS):
Nice to see a real antenna question from an actual radio amateur...
It seems to me that two of your choices a
1. Distributing seven elements on the same boom using the same
attachment points. All except the front (smallest) element could be
lengthened by a constant ratio so that the rear (longest) element is
self resonant at about 12 MHz. An estimate for the ratio by which
elements are lengthened may be found by dividing 18 by 14.
Seven elements to cover the octave you are interested in on a six
meter boom is OK, but a longer boom and a few more elements can provide
less variation in VSWR with frequency and more gain.
2. It sounds as if the boom you have is of one piece. [One alternate
scheme for the boom of a LPDA is to construct the boom in two pieces so
that the boom is also the transposing transmission line.] I say this
because you mention "crossover straps for phasing."
Thus an alternative is to leave what you have alone and extend the
boom. Place additional elements along the extension spaced with the
same ratio presently used and having lengths that progress with the same
ratio presently used. This might involve the least amount of work and
certainly would produce a better antenna. The extension of the boom
might be a size larger than the present boom so as better to support the
longer elements and so as to facilitate "splicing" to the present boom.

Extending is what I would do.
73, Mac N8TT
--
J. Mc Laughlin - Michigan USA
Home:

"TS" wrote in message
...
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

Hi Mac

The lengthening of the boom and the further scaling of larger elements does
sound like a damn good idea ! Thanks for the ideas,,,,much appreciated.

Cheers and 73's
Tony VK2TS

"J. McLaughlin" wrote in message
...
Dear Tony (VK2TS):
Nice to see a real antenna question from an actual radio amateur...
It seems to me that two of your choices a
1. Distributing seven elements on the same boom using the same
attachment points. All except the front (smallest) element could be
lengthened by a constant ratio so that the rear (longest) element is
self resonant at about 12 MHz. An estimate for the ratio by which
elements are lengthened may be found by dividing 18 by 14.
Seven elements to cover the octave you are interested in on a six
meter boom is OK, but a longer boom and a few more elements can provide
less variation in VSWR with frequency and more gain.
2. It sounds as if the boom you have is of one piece. [One alternate
scheme for the boom of a LPDA is to construct the boom in two pieces so
that the boom is also the transposing transmission line.] I say this
because you mention "crossover straps for phasing."
Thus an alternative is to leave what you have alone and extend the
boom. Place additional elements along the extension spaced with the
same ratio presently used and having lengths that progress with the same
ratio presently used. This might involve the least amount of work and
certainly would produce a better antenna. The extension of the boom
might be a size larger than the present boom so as better to support the
longer elements and so as to facilitate "splicing" to the present boom.

Extending is what I would do.
73, Mac N8TT
--
J. Mc Laughlin - Michigan USA
Home:

"TS" wrote in message
...
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

Dear Tony: You are welcome.
What might, or might not as I have only minimal information, prove
to be the easy way to scale the new elements is to realize that the tips
of the new elements will be close to being in line with the tips of the
"old" elements. This is close enough particularly if, to maintain the
principle of each element being designed to fail with the same amount of
wind/ice pressure, the majority of the ends of the new elements are of
the same diameter as those of the "old" elements. In other words, if
the original antenna was designed to the above principle, the new
elements will look like the longest "old" element with added buts that
are larger. Having the additional boom be the next size larger than the
old boom facilitates this and the splicing of the booms. Consider a
"plastic" rope strut to stiffen the boom.
Ice may well not be a major consideration for you as it is here.
However, a few years of wind induced vibration has a tendency to damage
the places where the longer elements are attached to the boom. Internal
and/or external boom/element sleeves in those areas can extend the
lifetime significantly.
Keep us all posted on your progress. Several of us will be
interested in the specifics of the original antenna.
73, Mac N8TT
--
J. Mc Laughlin - Michigan USA
Home:

"TS" wrote in message
...
Hi Mac

The lengthening of the boom and the further scaling of larger elements
does
sound like a damn good idea ! Thanks for the ideas,,,,much
appreciated.

Cheers and 73's
Tony VK2TS

"J. McLaughlin" wrote in message
...
Dear Tony (VK2TS):
Nice to see a real antenna question from an actual radio
amateur...
It seems to me that two of your choices a
1. Distributing seven elements on the same boom using the same
attachment points. All except the front (smallest) element could be
lengthened by a constant ratio so that the rear (longest) element is
self resonant at about 12 MHz. An estimate for the ratio by which
elements are lengthened may be found by dividing 18 by 14.
Seven elements to cover the octave you are interested in on a
six
meter boom is OK, but a longer boom and a few more elements can
provide
less variation in VSWR with frequency and more gain.
2. It sounds as if the boom you have is of one piece. [One
alternate
scheme for the boom of a LPDA is to construct the boom in two pieces
so
that the boom is also the transposing transmission line.] I say
this
because you mention "crossover straps for phasing."
Thus an alternative is to leave what you have alone and extend
the
boom. Place additional elements along the extension spaced with the
same ratio presently used and having lengths that progress with the
same
ratio presently used. This might involve the least amount of work
and
certainly would produce a better antenna. The extension of the boom
might be a size larger than the present boom so as better to support
the
longer elements and so as to facilitate "splicing" to the present
boom.

Extending is what I would do.
73, Mac N8TT
--
J. Mc Laughlin - Michigan USA
Home:

Tony,

Adding more elements seems like the only practical solution. You would
probably have to add 6 -8 feet to the boom, and 2 more elements. Keep in
mind the longest element will be about 38 feet long. That is why they make
the 18 -30 MHz version. BTW, Tennadyne used to make an 18 -30, but I don't
see that listed on their web site any more. You might want to check them out
anyhow for any ideas.

Tam/WB2TT
"TS" wrote in message
...
Hi Mac

The lengthening of the boom and the further scaling of larger elements
does
sound like a damn good idea ! Thanks for the ideas,,,,much appreciated.

Cheers and 73's
Tony VK2TS

"J. McLaughlin" wrote in message
...
Dear Tony (VK2TS):
Nice to see a real antenna question from an actual radio amateur...

Extending is what I would do.
73, Mac N8TT
--
J. Mc Laughlin - Michigan USA
Home: