Loading ...
Sorry, an error occurred while loading the content.

Re: horizontal loop with improved takeoff angle?

Expand Messages
  • victor
    what about the K6STI loop? Looks like a closed Alford loop. I use this Antenna for receiving 160-10 without the K6STI matching network, just a 1:1 current
    Message 1 of 14 , Sep 4, 2007
    View Source
    • 0 Attachment
      what about the K6STI loop? Looks like a closed Alford loop. I use this
      Antenna for receiving 160-10 without the K6STI matching network, just a
      1:1 current balun.
    • victor
      what about the K6STI loop,clames to have a improved takeoff angle. It looks like a closed Alford loop. I use this Antenna for receiving 160- 10 without the
      Message 2 of 14 , Sep 4, 2007
      View Source
      • 0 Attachment
        what about the K6STI loop,clames to have a improved takeoff angle. It
        looks like a closed Alford loop. I use this Antenna for receiving 160-
        10 without the K6STI matching network, just a 1:1 current balun.
      • Bruce Conner
        Murray, I m going to put a big resistor (50K 2W nowirewound) on one corner of the triangle to drain off static charge (as has been suggested elsewhere). Does
        Message 3 of 14 , Sep 22, 2007
        View Source
        • 0 Attachment
          Murray,

          I'm going to put a big resistor (50K 2W nowirewound) on one corner of
          the triangle to drain off static charge (as has been suggested
          elsewhere). Does it matter where I put this, and can I use that same
          corner for a real "spark gap" arrestor? I'm not looking for major
          strike protection here, I'm pretty safe from that where I am, but I do
          worry about static buildup frying my solid state receiver front ends.

          I was thinking of putting it at the corner furthest from the house.
          It might afford some better protection in the event of a big surge
          with a nearby strike. Any reason you have to put a spark gap on both
          legs of the ladder line instead of just one corner of the loop?

          Bruce
          WB8OGK

          --- In loopantennas@yahoogroups.com, "Murray Lycan" <zk2boy@...> wrote:
          >
          > Getting one corner of the triangle higher will help. It seems every
          > bit of height, however you get it, helps. I have one tower so, for a
          > while, I had one loop corner at 85 feet and the other two corners at
          > about 20 feet on nearby trees. Very sloping antenna. But it worked
          > quite well. Once I discovered that a slingshot would allow me to put
          > ropes high into the trees and get the other two corners higher is when
          > the loop got exciting. I started hearing the DX better and getting out
          > much better.
          >
          > 30 feet high for the loop is OK, but at that height you might be
          > happier with a directional rotatable antenna (if that's even possible
          > for you) or a vertical, if its receive noise is reasonable. Loop
          > receive noise is very low compared with a vertical here. With 1 acre,
          > you must have trees? Use them.
          >
          > Have fun with it 'cuz getting there is more fun than being there.
          >
          > Murray
          > VE7HA
          >
          > --- In loopantennas@yahoogroups.com, "Bruce Conner" <bruce.conner@>
          > wrote:
          >
          > ........So, assuming I'm looking at 30 feet for my highest
          > > point(s) is a triangle still my best bet? Could I get any improvement
          > > in takeoff angle if one corner were near the ground so the loop was
          > > tilted? Or would the increasing proximity of the ground cancel that
          > > out? I'd be OK with having a better takeoff facing east toward Europe
          > > if i had to choose.
          > >
          > > Bruce
          > > WB8OGK
          > >
          >
        • Dave Taylor
          Bruce: Just a thought here: The dialectric strength of air is normally 3 × 106 V/m. So a 1 mm spark gap (0.0394 inches) needs about **30 kv** to spark over.
          Message 4 of 14 , Sep 22, 2007
          View Source
          • 0 Attachment
            Bruce:



            Just a thought here:



            The dialectric strength of air is normally 3 × 106 V/m. So a 1 mm spark gap
            (0.0394 inches) needs about **30 kv** to spark over. Methinks your receiver
            front end would be gone long before your spark gap wakes up and tries to
            “protect” your receiver.



            Perhaps it would be better to use gas discharge protection after your balun?
            This would limit the antenna voltage to 70-90 volts. You might even find a
            way to insert a gas device into each leg before the balun?



            Cheers, Dave





            _____

            From: loopantennas@yahoogroups.com [mailto:loopantennas@yahoogroups.com] On
            Behalf Of Bruce Conner
            Sent: Saturday, September 22, 2007 3:01 PM
            To: loopantennas@yahoogroups.com
            Subject: [loopantennas] Re: horizontal loop with improved takeoff angle?



            Murray,

            I'm going to put a big resistor (50K 2W nowirewound) on one corner of
            the triangle to drain off static charge (as has been suggested
            elsewhere). Does it matter where I put this, and can I use that same
            corner for a real "spark gap" arrestor? I'm not looking for major
            strike protection here, I'm pretty safe from that where I am, but I do
            worry about static buildup frying my solid state receiver front ends.

            I was thinking of putting it at the corner furthest from the house.
            It might afford some better protection in the event of a big surge
            with a nearby strike. Any reason you have to put a spark gap on both
            legs of the ladder line instead of just one corner of the loop?

            Bruce
            WB8OGK

            --- In loopantennas@ <mailto:loopantennas%40yahoogroups.com>
            yahoogroups.com, "Murray Lycan" <zk2boy@...> wrote:
            >
            > Getting one corner of the triangle higher will help. It seems every
            > bit of height, however you get it, helps. I have one tower so, for a
            > while, I had one loop corner at 85 feet and the other two corners at
            > about 20 feet on nearby trees. Very sloping antenna. But it worked
            > quite well. Once I discovered that a slingshot would allow me to put
            > ropes high into the trees and get the other two corners higher is when
            > the loop got exciting. I started hearing the DX better and getting out
            > much better.
            >
            > 30 feet high for the loop is OK, but at that height you might be
            > happier with a directional rotatable antenna (if that's even possible
            > for you) or a vertical, if its receive noise is reasonable. Loop
            > receive noise is very low compared with a vertical here. With 1 acre,
            > you must have trees? Use them.
            >
            > Have fun with it 'cuz getting there is more fun than being there.
            >
            > Murray
            > VE7HA
            >
            > --- In loopantennas@ <mailto:loopantennas%40yahoogroups.com>
            yahoogroups.com, "Bruce Conner" <bruce.conner@>
            > wrote:
            >
            > ........So, assuming I'm looking at 30 feet for my highest
            > > point(s) is a triangle still my best bet? Could I get any improvement
            > > in takeoff angle if one corner were near the ground so the loop was
            > > tilted? Or would the increasing proximity of the ground cancel that
            > > out? I'd be OK with having a better takeoff facing east toward Europe
            > > if i had to choose.
            > >
            > > Bruce
            > > WB8OGK
            > >
            >





            [Non-text portions of this message have been removed]
          • Paul Birke
            Dear Dave at standard pressure and temperature the sparkover of air is about 28.5 kv/inch thus 0.0394*28.5=1123 volts maybe same result as you say to the balun
            Message 5 of 14 , Sep 24, 2007
            View Source
            • 0 Attachment
              Dear Dave

              at standard pressure and temperature
              the sparkover of air is about 28.5 kv/inch

              thus 0.0394*28.5=1123 volts

              maybe same result as you say to the balun

              best
              Paul

              ----- Original Message ----
              From: Dave Taylor <dave@...>
              To: loopantennas@yahoogroups.com
              Sent: Saturday, September 22, 2007 7:14:12 PM
              Subject: RE: [loopantennas] Re: horizontal loop with improved takeoff angle?













              Bruce:



              Just a thought here:



              The dialectric strength of air is normally 3 � 106 V/m. So a 1 mm spark gap

              (0.0394 inches) needs about **30 kv** to spark over. Methinks your receiver

              front end would be gone long before your spark gap wakes up and tries to

              �protect� your receiver.



              Perhaps it would be better to use gas discharge protection after your balun?

              This would limit the antenna voltage to 70-90 volts. You might even find a

              way to insert a gas device into each leg before the balun?



              Cheers, Dave



              _____



              From: loopantennas@ yahoogroups. com [mailto:loopantennas@ yahoogroups. com] On

              Behalf Of Bruce Conner

              Sent: Saturday, September 22, 2007 3:01 PM

              To: loopantennas@ yahoogroups. com

              Subject: [loopantennas] Re: horizontal loop with improved takeoff angle?



              Murray,



              I'm going to put a big resistor (50K 2W nowirewound) on one corner of

              the triangle to drain off static charge (as has been suggested

              elsewhere). Does it matter where I put this, and can I use that same

              corner for a real "spark gap" arrestor? I'm not looking for major

              strike protection here, I'm pretty safe from that where I am, but I do

              worry about static buildup frying my solid state receiver front ends.



              I was thinking of putting it at the corner furthest from the house.

              It might afford some better protection in the event of a big surge

              with a nearby strike. Any reason you have to put a spark gap on both

              legs of the ladder line instead of just one corner of the loop?



              Bruce

              WB8OGK



              --- In loopantennas@ <mailto:loopantenna s%40yahoogroups. com>

              yahoogroups. com, "Murray Lycan" <zk2boy@...> wrote:

              >

              > Getting one corner of the triangle higher will help. It seems every

              > bit of height, however you get it, helps. I have one tower so, for a

              > while, I had one loop corner at 85 feet and the other two corners at

              > about 20 feet on nearby trees. Very sloping antenna. But it worked

              > quite well. Once I discovered that a slingshot would allow me to put

              > ropes high into the trees and get the other two corners higher is when

              > the loop got exciting. I started hearing the DX better and getting out

              > much better.

              >

              > 30 feet high for the loop is OK, but at that height you might be

              > happier with a directional rotatable antenna (if that's even possible

              > for you) or a vertical, if its receive noise is reasonable. Loop

              > receive noise is very low compared with a vertical here. With 1 acre,

              > you must have trees? Use them.

              >

              > Have fun with it 'cuz getting there is more fun than being there.

              >

              > Murray

              > VE7HA

              >

              > --- In loopantennas@ <mailto:loopantenna s%40yahoogroups. com>

              yahoogroups. com, "Bruce Conner" <bruce.conner@ >

              > wrote:

              >

              > ........So, assuming I'm looking at 30 feet for my highest

              > > point(s) is a triangle still my best bet? Could I get any improvement

              > > in takeoff angle if one corner were near the ground so the loop was

              > > tilted? Or would the increasing proximity of the ground cancel that

              > > out? I'd be OK with having a better takeoff facing east toward Europe

              > > if i had to choose.

              > >

              > > Bruce

              > > WB8OGK

              > >

              >



              [Non-text portions of this message have been removed]














              <!--

              #ygrp-mkp{
              border:1px solid #d8d8d8;font-family:Arial;margin:14px 0px;padding:0px 14px;}
              #ygrp-mkp hr{
              border:1px solid #d8d8d8;}
              #ygrp-mkp #hd{
              color:#628c2a;font-size:85%;font-weight:bold;line-height:122%;margin:10px 0px;}
              #ygrp-mkp #ads{
              margin-bottom:10px;}
              #ygrp-mkp .ad{
              padding:0 0;}
              #ygrp-mkp .ad a{
              color:#0000ff;text-decoration:none;}
              -->



              <!--

              #ygrp-sponsor #ygrp-lc{
              font-family:Arial;}
              #ygrp-sponsor #ygrp-lc #hd{
              margin:10px 0px;font-weight:bold;font-size:78%;line-height:122%;}
              #ygrp-sponsor #ygrp-lc .ad{
              margin-bottom:10px;padding:0 0;}
              -->



              <!--

              #ygrp-mlmsg {font-size:13px;font-family:arial, helvetica, clean, sans-serif;}
              #ygrp-mlmsg table {font-size:inherit;font:100%;}
              #ygrp-mlmsg select, input, textarea {font:99% arial, helvetica, clean, sans-serif;}
              #ygrp-mlmsg pre, code {font:115% monospace;}
              #ygrp-mlmsg * {line-height:1.22em;}
              #ygrp-text{
              font-family:Georgia;
              }
              #ygrp-text p{
              margin:0 0 1em 0;}
              #ygrp-tpmsgs{
              font-family:Arial;
              clear:both;}
              #ygrp-vitnav{
              padding-top:10px;font-family:Verdana;font-size:77%;margin:0;}
              #ygrp-vitnav a{
              padding:0 1px;}
              #ygrp-actbar{
              clear:both;margin:25px 0;white-space:nowrap;color:#666;text-align:right;}
              #ygrp-actbar .left{
              float:left;white-space:nowrap;}
              .bld{font-weight:bold;}
              #ygrp-grft{
              font-family:Verdana;font-size:77%;padding:15px 0;}
              #ygrp-ft{
              font-family:verdana;font-size:77%;border-top:1px solid #666;
              padding:5px 0;
              }
              #ygrp-mlmsg #logo{
              padding-bottom:10px;}

              #ygrp-vital{
              background-color:#e0ecee;margin-bottom:20px;padding:2px 0 8px 8px;}
              #ygrp-vital #vithd{
              font-size:77%;font-family:Verdana;font-weight:bold;color:#333;text-transform:uppercase;}
              #ygrp-vital ul{
              padding:0;margin:2px 0;}
              #ygrp-vital ul li{
              list-style-type:none;clear:both;border:1px solid #e0ecee;
              }
              #ygrp-vital ul li .ct{
              font-weight:bold;color:#ff7900;float:right;width:2em;text-align:right;padding-right:.5em;}
              #ygrp-vital ul li .cat{
              font-weight:bold;}
              #ygrp-vital a{
              text-decoration:none;}

              #ygrp-vital a:hover{
              text-decoration:underline;}

              #ygrp-sponsor #hd{
              color:#999;font-size:77%;}
              #ygrp-sponsor #ov{
              padding:6px 13px;background-color:#e0ecee;margin-bottom:20px;}
              #ygrp-sponsor #ov ul{
              padding:0 0 0 8px;margin:0;}
              #ygrp-sponsor #ov li{
              list-style-type:square;padding:6px 0;font-size:77%;}
              #ygrp-sponsor #ov li a{
              text-decoration:none;font-size:130%;}
              #ygrp-sponsor #nc{
              background-color:#eee;margin-bottom:20px;padding:0 8px;}
              #ygrp-sponsor .ad{
              padding:8px 0;}
              #ygrp-sponsor .ad #hd1{
              font-family:Arial;font-weight:bold;color:#628c2a;font-size:100%;line-height:122%;}
              #ygrp-sponsor .ad a{
              text-decoration:none;}
              #ygrp-sponsor .ad a:hover{
              text-decoration:underline;}
              #ygrp-sponsor .ad p{
              margin:0;}
              o{font-size:0;}
              .MsoNormal{
              margin:0 0 0 0;}
              #ygrp-text tt{
              font-size:120%;}
              blockquote{margin:0 0 0 4px;}
              .replbq{margin:4;}
              -->







              [Non-text portions of this message have been removed]
            • mhatlau
              Several things. Dave, Paul is right, as any TV Repairman can tell you. And yes, setting an undischarged CRT in your lap does get the juices going so to
              Message 6 of 14 , Sep 26, 2007
              View Source
              • 0 Attachment
                Several things.

                Dave, Paul is right, as any TV Repairman can tell you. And yes,
                setting an undischarged CRT in your lap does 'get the juices going' so
                to speak:)

                Also, Dave, the spark Gap is not there to protect against overvoltage
                like what you imply. The action of a spark gap as protection against
                nearby Lightning is much more complicated. First, Lightning is not
                Direct Current. It is actually RF. Second, the damage is done by the
                decay time rather than the attack time. This is because the attack
                time is in microseconds (about 4 if I remember), and the decay time of
                40-100 microseconds or longer is where the heating occurs which does
                the damage. As the lightning current goes through a conductor, the
                inductance of that conductor degrades the attack time. If you look at
                the waveform near the antenna, the attack time is much faster than
                near the receiver. A Spark Gap takes advantage of this. In the
                example given, when the Spark Gap 'breaks over' at 1100 volts, the
                spark forms. This immediately forms a ionized pathway between the
                points. Since this path has a much lower resistance, the voltage
                across the spark gap decreases significantly, this quenches the
                remaining decay voltage to much less than 1100 volts. Think of a Neon
                bulb. You can apply 50 volts to it all day, and it wont light. But
                apply a 90 volt spike, and the bulb will light, and say happily on at
                50 volts. I have seen NE-2's that will stay lit at only 20 volts.

                Another example is a wideband jamming transmitter we produced. To get
                a cheap source of power at 2 GHZ with a bandwidth of several hundred
                MHz, we used a multistage Voltage doubler to build up a bit over two
                thousand volts very rapidly (on the order of less than a hundred
                microseconds.) This voltage was applied across a reversed diode,
                causing it to go into Avalanche mode of conduction. The discharge
                current is tremendous, if very short.And that discharge is what
                generated the RF power we needed. This mode of RF Pulse Generation
                harkens back to the early days of Radar, where an actual spark gap was
                used on a rotating shaft. The point being that we were applying
                kilovolt voltage spikes across a diode with only a 100 volt PIV
                rating. In other words, apply two hundred volts reverse voltage
                across the diode, and it will fail. But in that application it was
                very reliable because the current spike was short enough that no
                appreciable heat was generated.

                As long as the spark gap avalanches before the magnetic field has time
                to build appreciably, then the resulting output from the inductor will
                be much lower than the avalanche voltage of the spark gap. And even
                though the resulting voltage may exceed the voltage ratings of the
                device, the time the voltage is high is short enough to minimize or
                eliminate permanent damage.

                --- In loopantennas@yahoogroups.com, Paul Birke <nonlinear@...> wrote:
                >
                > Dear Dave
                >
                > at standard pressure and temperature
                > the sparkover of air is about 28.5 kv/inch
                >
                > thus 0.0394*28.5=1123 volts
                >
                > maybe same result as you say to the balun
                >
                > best
                > Paul
                >
                > ----- Original Message ----
                > From: Dave Taylor <dave@...>
                > To: loopantennas@yahoogroups.com
                > Sent: Saturday, September 22, 2007 7:14:12 PM
                > Subject: RE: [loopantennas] Re: horizontal loop with improved
                takeoff angle?
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                > Bruce:
                >
                >
                >
                > Just a thought here:
                >
                >
                >
                > The dialectric strength of air is normally 3 × 106 V/m. So a 1 mm
                spark gap
                >
                > (0.0394 inches) needs about **30 kv** to spark over. Methinks your
                receiver
                >
                > front end would be gone long before your spark gap wakes up and tries to
                >
                > "protect" your receiver.
                >
                >
                >
                > Perhaps it would be better to use gas discharge protection after
                your balun?
                >
                > This would limit the antenna voltage to 70-90 volts. You might even
                find a
                >
                > way to insert a gas device into each leg before the balun?
                >
                >
                >
                > Cheers, Dave
                >
                >
                >
                > _____
                >
                >
                >
                > From: loopantennas@ yahoogroups. com [mailto:loopantennas@
                yahoogroups. com] On
                >
                > Behalf Of Bruce Conner
                >
                > Sent: Saturday, September 22, 2007 3:01 PM
                >
                > To: loopantennas@ yahoogroups. com
                >
                > Subject: [loopantennas] Re: horizontal loop with improved takeoff angle?
                >
                >
                >
                > Murray,
                >
                >
                >
                > I'm going to put a big resistor (50K 2W nowirewound) on one corner of
                >
                > the triangle to drain off static charge (as has been suggested
                >
                > elsewhere). Does it matter where I put this, and can I use that same
                >
                > corner for a real "spark gap" arrestor? I'm not looking for major
                >
                > strike protection here, I'm pretty safe from that where I am, but I do
                >
                > worry about static buildup frying my solid state receiver front ends.
                >
                >
                >
                > I was thinking of putting it at the corner furthest from the house.
                >
                > It might afford some better protection in the event of a big surge
                >
                > with a nearby strike. Any reason you have to put a spark gap on both
                >
                > legs of the ladder line instead of just one corner of the loop?
                >
                >
                >
                > Bruce
                >
                > WB8OGK
                >
              Your message has been successfully submitted and would be delivered to recipients shortly.