[TowerTalk] Stacked Skip-Log, Yagi's & L-Networks, Broadband Matching Harnesses
K7GCO@aol.com
K7GCO@aol.com
Tue, 19 Dec 2000 22:14:36 EST
In a message dated 12/8/00 12:28:31 PM Pacific Standard Time,
wx0b@arraysolutions.com writes:
<< Ken,
This is way to much for me to respond to.
Bottom line:
Your L-network is way to difficult for anyone to make. A Wide band
transformer works every time and for everyone.
******How would you know--you haven't seen or used it.
I Have stacked over 1600 yagis, quads, LPDAs, and Tribanders, and verticals
with this technique. The interaction is minimimal if noticable at all at .5
WL.
*******Look at it in Eznec for 2 element quads or Skip Logs as I suggested.
If there is "minimal interference" between stacked beams at .5 WL, how come
so many stacked beams of higher gain, much wider spacings and sharper
vertical patterns often have their F/B's RUINED when used individually or
together! That's not hardly what I call "MinimalI Interaction." I don't
know what the irrevalent reference to "verticals" above was for as vertically
stacked 1/2 wave verticals cleanly fed wouldn't even see each other real
close with the deep nulls in their patterns pointing at each other.
I just did a big deal on a VHF/UHF radar set up with two T31 Teannadyne
Logs (nice beam!), 110mhz to 500 Mhz and the wide band xfmr I made for them
works.
********I'm sure that was good for business and it works fine.
I doubt very much if an L network would ever work without a ton of switching
out of L and C.
*******For the application I suggested it works just fine. The 2
configurations changing switches I use in my Universal Tuner weigh less than
1/2 lb. But it's not even needed as the resistive load stays about the same
(no reactance swings like a yagi) therefore the L-Network configuration--says
the same. It's the "Ultimate in Simplicity & Bandwidth" for the cost. It
should only need a touch up for 1:1 SWR across the entire frequency range. I
don't know what your average SWR is with your system and I'm not aware of any
matching adjustments you might have. I just love 1:1 SWR for my 50 ohm
output rigs--all the time and at any frequency.
Plus the relay or switch inductance would be impossible to predict and
correct for in my lifetime.
********No big time consuming predictions were necessary in your or my
lifetime (no relays used either--does yours?). The loads are obvious in just
a few seconds.
It's not worth the effort to use L netorks over one band.
********I beg to differ since I've done it and you haven't. How can you be
so sure? I have another even simplier system for one band.
Sorry to disagree with you but your not going to convince me it will work
otherwise.
*********Try an open mind M-matching network.
What your saying is you have 4 L networks for each band segment. This is
not a practicle solution.
********No, what I'm saying is, I have 1 variable inductor and capacitor in
the Unblanced L that I'd use (it doesn't change) in this stacked Skip Log
configuration and 2 variable inductors and capacitors in my Balanced
L-Network configuration "All On One Shaft" in a sneaky sort of a way. I find
it a "very practical solution"--that works just fine. In fact I think I
could "Series Connect" the 2 feedlines for a 100 ohm load and match them in
phase (1 feedline 1/2 wave longer) with a Balanced L Network or a Johnson
Match Box. Now that's a very cute idea!
Use an Un-UN and enjoy being on the air.
********I'm sure it works but the cost of my configuration is very very
small. I enjoy being on the air also but I have to explain every suggestion
I make in detail for many. I'll continue to use it until you show me
something better. I have asked for it and it hasn't arrived so far. I'd
love to see it.
Love to continue but there is a contest on in a few hours, and I have 3
stacks to play with all using Un-Uns.
*******I have another configuration for stacked beams for one band that
allows selection of A/B/AB, with 1:1 SWR on all 3 combo's AND with additional
bandwidth (everyone loves more bandwidth) for both (AB), No TOROID saturation
losses and cost about $10 for anyone to make. DXer's who use it rave about
it. I hear yours cost about $500--correct me if I'm wrong. Hey I'm retired
and Ham Radio is living off mostly retirees on SS. We have tight budgets, 10
more hours a day to spend money, I'm into 3 other technical areas and I
didn't save much. I thought the $ supply never ended and unfortunately it
comes without instructions for proper use. K7GCO
73, Jay
Jay: I described my "Universal L-Network Tuner" in a previous Post to
match just about anything and it would be a good construction article for one
of the mags or some Mfg to make. But for stacked LP's, just one L-Network
configuration is needed to match the mostly resistive load of a coax from
each LP parallel connected. There would not be the typical reactance swings
of yagis and you know that. Anyone can make the L Network for that in about
15 minutes. I find the L-Network has greater bandwidth than any other tuner
as it's a non resonant circuit and has the least loss. I use reltively small
flee market componets for 1 KW levels with no heating or arcing typical of
other systems. I rest my case.
I have a 40M quad loop horizontally orientated fed with a 1/2 wave of open
wire line into a "Balanced L-Network" with all components on "1 Shaft" (for
fast tune ups) I have been able to operate over 1 MHz at 1:1 SWR with no
change. It had compensating reactances which few tuners do. No other tuner
can do that I've used. These are things one finds out when circuits are
properly used and "eye popers" like this show up.
With 2 element stacked beams 1/2 wave apart, there "is indeed" interference
of individual Z's and frequent upset of F/B--even at wider spacings. When
one is used individually, the unused one affects the vertical pattern of the
driven one which you don't see rotating the beams but you will clearly see if
you check it in Eznec or if they were vertically polarized on a horizontal
boom and individually used. The lower the gain of each beam and the closer
the spacing needed for the best stacked pattern, the more the affect on each
other. It's very clear. Mostly the higher gain beams are stacked, have
sharper vertical patterns and requires wider spacing for maximum gain which
tends to minimize the affects on each other when individually used. Eznec
has not lied to me yet and I or anyone can measure F/B changes on the S
meter. Impedance changes can be seen in the SWR changes--exact Z changes in
Eznec.
Your doubts of practicality and time predictions of working out the design or
whatever you were trying to say on what I have, are unjustified as you have
not seen what I have or how it works.
Your balun matching for 2 beams arrangements sounds like it works great. I
had asked for details of your system that has not been forthcoming. I'd like
to see it. I've heard it costs around $500. My 1 band stacked matching
harness attached to a coax switch I use in the shack, is where I select
either or both beams (all 3 combo's with 1:1 SWR) with additional bandwidth
(with both beams) costs about $10 to make. It's the ultimate of simplicity
and cost which I often come up with. You sell your systems which I have no
quarrel with. I give most of mine away freely and some have also been stolen
with no payments.
I'm sorry you disagree with my practices but I know what they are, how well
they work, you don't, you haven't seen my systems, have no foudation to
criticize them just because they differ from yours views or what you sell and
I have nothing to sell. My procedures are often so simple and effective they
are not marketable. The use of my procedures is also a voluntary process.
Elk hunting I climbed this big hill and ran into a hunter's camp. The hunter
was shocked to see me and asked "how I got there." I said "I walked up the
hill from the hiway below about 1 mile". He said "I just paid this Indian
Guide $1000 to pack me 10 miles and a hard all day ride into the back country
for a private hunt." (He packed him in a $1000 circle.) He walked out with
me in 30 minutes and later told me he cancelled the Guide's check. We hunted
together again. He liked the simplicity of my routes better without bells
and whistles and the price was right.
I like to keep things simple and inexpensive which typifies many of my
suggested designs. Retirees don't have much money left over after taxes and
all the other expenses. You haven't seen or asked for the details of my 1
band system or L-Network. Most retirees with limited Ham Radio Money eagerly
investigate and try all kinds of ideas to reduce costs, improve performance
and the bandwidth of even the "Malighed L Networks"--you should also. Long
live the "Loney L-Network", it's 4 configurations, 2 element beams and Skip
Logs. I like the way they work just fine and I'll use them until shown
something better and within my budget. N4KG just had a great post on the
frequent effectivenes of the lower beam in DX contests which I have found
also--even 2 element quads and Skip-Logs. k7gco
"Now you know the rest of the L Network Story."
K7GCO@aol.com wrote:
> << In a message dated 12/6/00 8:22:32 PM Pacific Standard Time,
> wx0b@arraysolutions.com writes:
> <<
> That's not really a good idea Ken, I would point out that an L network
> has a very small bandwidth. I suggest to do it a different way. Use a
> matching network that is broadbanded. Like the StackMatch
wideband UN-UN transformer. Then the logs will have the proper
impedance matching over their entire bandwidth. So this the
technique.
>
> Run equal lengths of 50 ohm coax to a central point between the logs,
> place your Stackmatch here, it will match the logs properly to select
> U/L/Both. Then run a line of hardline down to the shack. It can be
CATV to save more money and have less loss. Match it with a couple
of 50:75 ohm UN-UN Xfrms.
>
> L networks are (all?) work at one frequency (not so). And I know that
K7GCO knows this, he probably just was in a hurry.
> > Jay, WX0B
>
> Jay: I will take some exception to your views based on a lot of use of
the L network (and I was in a hurry). I have a great system for stacked
beams that you would even like but didn't have time to describe it.
Without attachments even a simple circuit is hard to describe without
a bunch of E-mails to follow. I'll have a Web Site in SD as the SD
Antenna Club with my old call "W Zero Lice, Mice & Bedbugs" for
material like this and some of the mags like AntenneX which every
TTer should read. Cebik had a great LP with F/B like I have never
seen before and will build.
>
> First off it's assumed the Skip Log or Normal LP's that are horizontally
> spaced (in this example) wide enough to minimize the affect each has
on the other when used individually and the different Z's presented at
the feedpoints due to the difference in heights off the ground. For this
> installation one would have to live with the vertical pattern affects and
Z's on each other individually when only one or the other is used and the
> different Z affects on each one from the ground. A compromise
spacing was suggested not for 15M but 17M just to minimize this
coupling problem. I've never read anyone warning of the affect one
stacked beam has on the other when used individually as I can do with
my switching harness. I saw the interference in Eznec. Most use both
together full time which is a serious mistake. The spacing I suggested
is most likely too wide on 10M. On 10M it sharpens the free space
vertical lobe even more but doesn't increase the gain and 2 ears start to
form. On 20M the spacing is too close and the full 3 dB gain is not
obtained but it's less of a compromise than if they were optimally
spaced for 15M.
>
> The pattern distortion when either one is used alone (to make use of
the different angles of radiation between the 2 beams) is a problem
that I tried to minimize. Fortunately this problem is minimized the
higher the gain of the beams used in stacks for 2 reasons. The
vertical patterns are progressively sharper with higher gain which
means less coupling between them vertically when used separately
and the spacing also has to be wider to obtain the max gain with
stacked beams--both +'s. The LP's would couple to each other more
as their vertical patterns are much broader (why they work so
well close to the ground), and a closer electrical spacing is required
when stacked. So the assumption is made that with equal length
feedlines the Z at the end of each feedline will be very close to each
other and you will have to live with it. I also use my "Magic Length" of
91' 2" (.66 VF) or multiples as it will be a 1/2 wave or multiples at
3.562, 7.125, 10.67, 14.25, 17.81, 21.375, 24.937& 28.5 MHz.
Resonant coax lengths reduce reactance's and repeats the R value
of the Z at the feedpoint. If longer lengths are needed, you can add
lengths of 45' 6.9" and the 1/2 wave relationships will still hold.
>
> I have a very simple matching harness that goes on a coax switch for
this application that allows full power to each beam individually or both
together using 2-75 ohm 1/4 wave stubs with a unique switching
feature. It has a big bonus of giving additional bandwidth when both
are used due to the opposite reactance the 75 ohm 1/4 wave stubs
create above and below the center frequency. I've got a lot of rave
notices of this system (at least worth a dinner) from many on it
including DXer Lou Gordon K4VX. I didn't mention it as the 1/4 wave
stubs would have to be changed for each band in the Skip Log.
>
> Now for those who suggested the typical V stacking where both feed
points are tied together for simplicity and 1 feedline, this is a bad
application for this concept when using short boom Skip Logs. It's the
most useful and effective for very long boom LP's. This physical
configuration essentially maintains the same and optimum electrical
spacing for the entire frequency range and has a minimum V angle.
With short boom LP's, the beams would have to be up to 90 degrees
or more to each other to optimize and balance the electrical spacing
on the upper and lower bands. Furthermore the part of the vertical
pattern pointing forward from each Skip Log would be down several dB
> and pattern addition straight forward is not at all optimum--forget it.
> Note! When 2 long wires are used in a Vee Beam configuration, they
are aligned so that each has a lobe going forward and parallel and only
3 dB is obtain in an optimum configuration. I have such a V log here for
the TV Channels of minimum elements using also a staggered element
elimination design and the Vee stacking didn't do a thing for it. Another
compromise failure. We need more of those who maximize their
designs (I've been known to lean that way), not this damn "Minimal
Design Bankruptcy" constantly jammed down our throat that wastes
everyone's money.
> My L networks seem to be a bit broader than yours or I didn't think they
> were narrow on applications just like this 25 proposed ohm load. I also
have what I call "One Knob Antenna Tuners" in 4 switchable L network
> configurations, shunt and series capacitance and inductance. It does
lots of things. Visualize this. The variable Xc (I use them a lot) is
on the
same shaft as on the inductor. As I rotate the inductor through each
turn, the Xc goes through 2 complete cycles and in about 5 seconds, I
can tune through the entire range of many many Z's it will match--in 4
different configurations. So I find 1:1 SWR real fast and can touch it up
quickly off frequency if needed.
>
> I've used this L Network configuration in a similar application.
Visualize 2 yagi's on the same boom at right angles to each other in
the "X Configuration". Each yagi is fed with equal length feedlines.
CBer's had a similar beam in a + configuration where they selected
either horizontal or vertical polarization. The vertically polarized DE
had to be a different length and had other adjustments than the
horizontal DE used due to the heavy coupling to the mast. The tower
was excited and lift off of the vertical pattern was substantial. I
used the
X configuration to reduce this coupling and to balance it up so the load
of each beam for the coax was the same. It still coupled but I have a
way to get rid of the tower interference now when vertically polarized.
I'm adapting it to a quad DE--when I get time.
>
> I have a switch box that allows me to select 6 different polarization's
from this "X Beam." I can select either beam for 45 degree
polarization left or right (direct feed), horizontal polarization (1/2
power
in each beam in phase), vertical polarization (1/2 power to each beam
180 degrees out of phase) and turnstile polarization CW or CCW with
1/2 power in each 90 or -90 degrees out of phase. To obtain 90 or
180 degree phasing I switch in these lengths of coaxes in series with
one coax in the proper way. For matching in-phase, the coaxes are
paralleled for 25 ohms and matched with (you guessed it) an L
Network. It uses relatively small coils and variable Xc's for 1 KW
> levels without heating or arcing in a small space--3 of them. Once the
> proper inductor of the L Network was found and tuned up in the middle
of the band I seldom had to adjust the Xc in the band edges. I had all
the bandwidth I needed with the matching and phasing hardware in a
small box and saw no need to look for a better system. I could have
used 2-75 ohm stubs for the matching part but didn't for reasons I don't
remember--some 50 years later. A CB mfg in Chicago tried to swindle
the design out of me--but failed. I seems that most mfgs want
everything I got free despite contracts. He could have had a great
money maker for us both laid in his hands but out right greed cost him
(and me) dearly. He could have had several other unique designs
also. Industry is notorious for this practice but there are exceptions.
>
> Anyhow horizontally stacked Skip or Norma Logs is a similar Z
matching design and by having a calibrated variable inductor and Xc
you can preset for each band or in-between frequency very quickly
instead of changing 1/4 wave stubs for each band or frequency for a
match. I'm eager to try my "L-Network Match Box" on horizontally
stacked LP's myself. I see no reason to use another matching system
at this time but would like to see a better system for flexibility.
Send
me the details of the Stack Match and I'll see if I can adapt it. I
have
the flexibility of selecting the top, bottom or both LP's in the shack--
without relays. I like to maximize the full potential of any system.
If I
can get more bandwidth I'm interested. I think I'll have plenty of
bandwidth as with the LP's I won't have the reactance swings typical
with
parasitic beams. Now I bet you knew that. Your concern of
L-Network use has been diminished by LP's. Long live the L-Network
until something else comes along that's better for this application.
>
> Although I was in a hurry I arrived at my suggested simple design I
posted on TT in about 5 seconds considering all these details I've
explained here as I've "been there and done that" in similar
applications. It took about 10 minutes to Post--but many hours to
answer. I've found that if I give too much info or too little (and
without
attachments) I have to justify or supply even more info--which I always
do. I would hope that you TTer's would by now have a little more
confidence in my suggestions. If I say it works--it works. I'd like to
remind you that you also got the info free of charge. There are some
with limited insights that make "great demands" for more and
> more free info as they can't derive it themselves. They are a form of
> "Technical Parasites" on "Technical Welfare." I normally charge for
> technical information. (If I charged you for what I said, would you have
more confidence in it?) I thought I'd make a quick suggestion, I was
properly challenged and I may and often learn of new techniques
myself which I'm always open for.
>
> Horizontal boom stacking LP's is a great idea that I started getting
myself about 15 years ago with the availability of them from 14 MHz to
higher frequencies and I knew how to match 2 of them stacked real
easy. About 40 years ago I tested one of the first LP's of the first
designers of it by the name of Dwight Isbel came up with. It was flat
from 60 to 150 MHz around 93 ohms. I still have a picture somewhere
of it and Isbel. He worked for Boeing in a fancy Antenna Lab and I
didn't, yet I was testing it for him.
>
> The lower gain of LP's is no detriment--it's an asset most of the time
when properly used. It's been a victim of uninformed critics who have
never used one. I'll have 2 M2 Skip Logs's stacked in SD (if I ever get
there) matched--you guessed it--with L Networks or a better systems if
there is one. This should explain why I do what I do (have I ever
misled
you?). During the mean time there should be some serious study of the
life and times of the "unseen vertical pattern" as you rotate the beam,
its size relationship (it's wider) to the horizontal pattern, gain and
Reflection Factors. It's time for more of you to get on Eznec and read
AntenneX mag on Internet. It's read in over 170 countries now.
K7GCO
> "Now you know the rest of the L Network story."
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