[TowerTalk] Stacked Skip-Log, Yagi's & L-Networks, Broadband
Matching Harnesses
Jay Terleski
wx0b@arraysolutions.com
Wed, 20 Dec 2000 11:27:38 -0600
Hi Ken,
Here we go again.....
In this installment, you make the claim that an L network can be
implemented that can have a bandwidth from 7-30 Mhz a range of 4
octaves, at a fraction of a cost of a Broad Band RF transformer. You
also tell story about an Elk hunter who got taken by an indian guide.
Am I to take it you are saying that my StackMatch is like being taken
for an indian ride?
Gosh Ken, I will ignore this for now so you can explain what you mean.
The rest of your comments is way to much redundant and lengthy. Let try
to distill it to a single issue or two using statements from your post.
>
> 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.
Send me a fax with your design and or pictures. I would love to be
convinced with real engineering drawings not stories. I will then run
the curves over the frequency bands with the network simulation software
for your L network and post the data in a following message. May Fax
number is 972 203 8811
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.
This I know, a well designed T network will outperform an L network for
bandwidth even with fixed Resistive loads.
>
>
>
> 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.
I have made lots of L and T networks. They work on one band and must be
adjusted to work over an octave yet alone 4 octaves of frequency.
>
> Your balun matching for 2 beams arrangements sounds like it works great.
Its a wide band RF Transformer, or UN-UN as Sevick has called them.
You suggest saturation, but the transformer is a flux canceling design.
Read Sevick's book. It has very little flux so huge power can be matched
to the loads. Loss is very low and it will work over 4 octaves of
frequency with no adjustments necessary.
I
> had asked for details of your system that has not been forthcoming.
Details have been published in the NCJ, and are on my website. It is
very much in the open Ken.
But I apologize, I never saw your request. No magic. Just an UN-UN and
some relays and a well designed PCB. 1.8 to 54 Mhz. And I lifetime
warranty. I think its worth the price don't you?
I'd like
> to see it. I've heard it costs around $500.
No its half that amount. http://www.arraysolutions.com take a look were
very proud of the StackMatch. Prices are on the price list which can
also be found on this site.
>
> 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.
When I lived in Colorado I took 9 elk in 9 years. Packed them all out
on my back. Most of them over 4 and 5 pointers (western count) I was
young and poor electrical engineer. But I got an elk every year since I
made up for it with being able to cover allot of ground on foot and I
studied their habits so I knew where to look.
Today I would probably hire the horses to save my back, and TIME.
Most hams would rather buy than build since they are working hard at one
or two jobs, and can make more money doing what they do well. They don't
have the time to build things like they wish they could. So I provide
this service.
Most Elk hunting packers I have met are legitimate too, and do a
wonderful job.
But I am not sure I can pull the trigger on an Elk again........
Jay
>
> "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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--
Jay Terleski
WX0B - Array Solutions
www.arraysolutions.com
--
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