On Thu, 16 Aug 2007 12:46:26 -0700, Richard Clark wrote:

You have a need, but you are not going to spend $300 to fill it. Again,
you say what is wrong, but not what is right. Will you spend $299?

I will investigate collecting together the parts from hither and yon and
building one myself, for less (sorry, can't define "less" but, like
pornography, I'll know it when I see it).

That was the objective behind whatever my original question was that had
to do with T2FDs. I'm pretty sure the original question had to do with
where I can buy suitable terminating resistors and bizarre-ratio baluns,
and which of the various and assorted configurations (390 ohm resistor
and 4:1 balun vs some higher resistance and ever more obscure
impedance-ratio baluns) is "best" (which is to say, least "bad"). But if
there was other stuff in my original question, please do me a favor and
don't toss it up in my face, OK? Answers to those questions (which I got,
both here and elsewhere) are sufficient for now.

The more specialized need requires higher power and a rotatable,
directional antenna, in the frequency range from something below 20
meters

Tell me that you want to spend less than $300 for this and we can all
have a chuckle.

Come on, Richard, can't you see the apples-to-oranges comparison?

I'm willing to spend $1000, if I have to, on a two element beam that
claims to work efficiently from 14 to 24 MHz (and beyond), IF it works as
advertised, because I have limited alternatives.

I'm not really willing to spend $300 on a radiating dummy load, because I
have LOTS of alternatives including building one myself for a lot less.

That can't be hard to understand, or differentiate between the two, can it?

Your questions tend toward seeking validation:
"Will X work for Y?"

To which some responses offer
"Um, yes, but why would you want to do that?"

"Because I don't what Z."

"OK, X for Y without Z can be found with model A."

"Model A will do, but it doesn't give me B."

"OK, X for Y without Z but with B."

This can go on for a long time.

I think it's called "doing some research" where questions beget answers
that then raise more questions that perhaps weren't thought of before,
until finally everything falls into place.

You want me to go away and come back with a full IEEE-STD-830-1998
requirements analysis before asking any questions. I've been doing that
kind of stuff for a living for a very long time and I'm pretty sure it
doesn't work that way... you ask questions, challenge the answers, come up
with more questions, and eventually you end up with what you need.

Is it the fact that I tend to challenge the answers ("Ah, yes, but what
about...?") that seems to bother you so much.

I'll tell you what, Richard, I appreciate the help you have provided so
far, I really do, but if it's all going to bug you so much may I suggest
that it's OK if you just stop responding to me? I'll miss your sage
advice but I guess I'll live with that...

Being meticulous about "efficient" would have you expressing what loss
is allowable.

2 db loss is unacceptable if it means I can't hear the stations I need to
hear, and they can't hear me.

18 db loss is fine if I can still hear them and they can hear me.

By inference to your tendency to select a T2FD (loss in the ballpark of
at least 3dB), then yes (and with proper design and construction), 0.07
wl spacing between elements is efficient

This is what I mean. Two completely different requirements, two completely
different solutions. Apples to oranges. And I have no "tendency to select
a T2FD". It's one of many options. But I think you knew that and you're
just having some fun at my expense, which is fine but it's over now. :-)

On Thu, 16 Aug 2007 12:46:26 -0700, Richard Clark wrote:

Doubling the dimensions of:
http://home.comcast.net/~kb7qhc/ante.../Cage/cage.htm
would satisfy 3/4ths of your spectrum requirement

At the risk of sounding negative again, is it OK if I point out that one
of my early needs involved NVIS operation (it's in one of my early posts),
and verticals in general and cages in particular aren't really suitable
for that?

Dear WA1RKT:

For less than $1000 you may purchase and use a LPDA that will
accomplish what you specify. Several such antennas are on the market or you
could construct one from scratch.

Some positive aspects of a LPDA:
1. no moving parts
2. "instant" BW so you may use the scanning you mentioned
3. using anything that is at all of a reasonable size, the antenna
inherently has low sensitivity to minor construction and other errors (much
favored in ice country because their performance degrades slowly with ice
coverage - not found to be true with a critically "tuned" yagi)
4. performance as constructed is close to that predicted with NEC -
tweaking is usually just not needed (occasionally, the shorting strap needs
to be tweaked)

Consider the conventional solution for the BW requirements you have set
out.

The StepR antennas work, but questions remain as to how well and for how
long. If I were to go on a trip to a salt-water DX entity, I sure would use
their vertical right on the beach. In other words, they are a solution to
some problems.

Good luck. 73, Mac N8TT

--
J. Mc Laughlin; Michigan U.S.A.
Home:
"Rick (W-A-one-R-K-T)" wrote in message
news


I'm willing to spend $1000, if I have to, on a two element beam that
claims to work efficiently from 14 to 24 MHz (and beyond), IF it works as
advertised, because I have limited alternatives.

On Thu, 16 Aug 2007 18:58:26 -0400, "Rick (W-A-one-R-K-T)"
wrote:

On Thu, 16 Aug 2007 12:46:26 -0700, Richard Clark wrote:

Doubling the dimensions of:
http://home.comcast.net/~kb7qhc/ante.../Cage/cage.htm
would satisfy 3/4ths of your spectrum requirement

At the risk of sounding negative again, is it OK if I point out that one
of my early needs involved NVIS operation (it's in one of my early posts),
and verticals in general and cages in particular aren't really suitable
for that?

A review of my response at that time offered a dipole of similar
construction in its place. It doesn't take much math (or rotation) to
shift from monopole to dipole.

There is NOTHING about a cage that makes it unsuited for NVIS. It may
be intractable, but that goes with the turf.

I wonder though about why this is so agonizing. If you work MARS/CAP,
it would seem that solutions would be there in pile-ups for the QST
tossed into radio land. That, or everyone is wandering in the
wilderness.

It is not like I haven't seen these questions about MARS/CAP asked
before, but most were satisfied with the air-cooled resistor and
didn't show much interest in efficiency (what for? there was no real
choice in the matter without several kilobucks of investment anyway).
Go to Salvation Army and buy toasters for lossy loads (they come in
1KW values for $5).

BalUn? When you characterize allowable efficiency as being between
-2dB and -18dB, then you don't even need a BalUn anymore. It's going
to cost you $1000 to rotate it (whatever "it" is). And if crisis (I
gotta hear them and they gotta hear me) drives the design, then you
have to open the wallet. Does anyone else in MARS/CAP get by with
less? In a dozen years I haven't seen a single post by one to claim
they do (or admit they couldn't hear or be heard).

You are going to have several many antennas. None are going to be
whole solutions. Some are going to be slow to tune. Some may never
tune. Some may never be heard. Propagation will be a cruel arbiter.
Guarantees won't be honored. This is pretty much the same fate in the
Ham bands, and out of band frequency doesn't alter this reality very
much.

Decide to build a farm efficiently. Select ranges of frequency
suitable to octaves, not decades. Point immovable antennas towards
your expected traffic. Or if you are filling in a network's uncovered
areas, point them in those directions (that is what a network is for,
isn't it?).

I taught HF/VHF/UHF comm systems in the Navy and served as senior
Petty Officer in CIC. There is no such thing as a single solution.

73's
Richard Clark, KB7QHC

On Thu, 16 Aug 2007 18:54:28 -0400, "Rick (W-A-one-R-K-T)"
wrote:

This is what I mean. Two completely different requirements, two completely
different solutions. Apples to oranges. And I have no "tendency to select
a T2FD". It's one of many options. But I think you knew that and you're
just having some fun at my expense, which is fine but it's over now. :-)

I haven't got a clue just what your apples and oranges are, actually.

73's
Richard Clark, KB7QHC

On Thu, 16 Aug 2007 23:22:43 -0400, J. Mc Laughlin wrote:

For less than $1000 you may purchase and use a LPDA that will
accomplish what you specify. Several such antennas are on the market or
you could construct one from scratch.

Good morning, Mac.

Yes, the log periodic was my other alternative to the SteppIR (in fact,
the SteppIR was something I've been considering to mitigate the size of
the LPDA). It should do well for the higher frequencies of interest (14
to 24 MHz).

At one time I considered a wire log periodic, pointing straight up, as an
NVIS antenna for the lower range (2 to about 8 MHz). Then I went to
lie down until the thought went away. :-)

Richard;

Thank you.

73,

Rick WA1RKT

Dear Rick:

Small (six element) LPDAs exist that have been used over the frequency
range of interest by amateurs and military. The SWR tends to oscillate with
frequency and the gain is reduced wrt to a larger LPDA, but they will work
for what you wish to do. Perhaps I have not interpreted "size" correctly.

I have some experience with wire LPDAs that point straight up. Many
years ago, a three (insert giggle) element was constructed to cover 4 to 6
MHz. Two towers. Three wires. It produced noticeable gain over a doublet.
I no longer remember how high the towers were.

An aside: 2:1 or 2.5:1 frequency coverage by a single LPDA is straight
forward. Larger ratios require one to consider more factors.

Perhaps one of the best antennas for covering the 4 to 5 MHz range is
the classic tropical broadcast antenna. At center frequency: two one WL
dipoles (fed in phase), 0.3 WL high and separated horizontally by 0.5 WL.
Bring the two, equal feeds to a central pole and place them in parallel. It
is possible to have a resulting impedance that is very acceptable. An
advantage of this system is that the coverage is close to being equal in
azimuth (at the TOAs of interest) and it has low sensitivity to distant,
interfering stations.

Consider investing in EZNEC and learning to use same.

Do let us know what your antenna system ends up being. 73, Mac
N8TT

--
J. Mc Laughlin; Michigan U.S.A.
Home:
"Rick (W-A-one-R-K-T)" wrote in message
news
On Thu, 16 Aug 2007 23:22:43 -0400, J. Mc Laughlin wrote:

For less than $1000 you may purchase and use a LPDA that will
accomplish what you specify. Several such antennas are on the market or
you could construct one from scratch.

Good morning, Mac.

Yes, the log periodic was my other alternative to the SteppIR (in fact,
the SteppIR was something I've been considering to mitigate the size of
the LPDA). It should do well for the higher frequencies of interest (14
to 24 MHz).

At one time I considered a wire log periodic, pointing straight up, as an
NVIS antenna for the lower range (2 to about 8 MHz). Then I went to
lie down until the thought went away. :-)