Re: Topband: Detuning transmit antenna in receive
There is no single solution for detuning an antenna it depends on electrical length. For verticals a quarter wavelength or less it is common to have a contactor between the network and the radiating element and open the connection to float that element. This is the practice in commercial directional arrays where some tower are not used in a day or night mode. This does not work well on taller towers and I do not know offhand how it would work with the T. It is easy enough to model in EZNEC. On 6/16/12 3:02 PM, Shoppa, Tim wrote: OK, several folks came back and recommended detuning my transmit antenna in receive. Certainly any receive antenna I have is going to be in the shadow of my transmit antenna, a 130-foot flat-top about 85 feet up, fed against ground. (Really it's an 80 meter doublet fed with ladder line. I tie the ladder line together at the bottom and feed against ground.) Trying to figure out what detune is. I match the transmit antenna to 50 ohm coax with a L network at the bottom. If I want to detune, then I can open up the connection between the antenna and the L network at the bottom? Unhook the L or C in the L network? Short out the antenna where it comes into the L network? I could rig up a relay contact to do any of those. Tim N3QE ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Receiving loops
Sensitivity is not always important. Small loops in general receive less noise and the real exercise is balancing the internal noise floor against the actual signal received. In some cases a loss up to 20 db can be acceptable the numbers are easy enough to run. On 6/16/12 8:17 PM, Brian Miller wrote: Hi Tim I also agree with the previous comments on this thread about detuning the transmit antenna (or any other wires/cables that are resonant on 160M) and isolating the coax feed line from the RX loop. It is also important to identify the direction of the main source of the noise and orientate the loop accordingly so that is being properly nulled. I use a small portable tuned loop to identify the direction of the noise.. Of course, if the noise is coming from the same direction as the DX then you are not going to see much (or any ) improvement in the signal-to-noise ratio. Also, if the noise sources are in multiple directions then it will also be difficult to null the noise properly. I have found that small tuned loops (with their bidirectional nulls) are often more effective in such a situation. One of the problems with small tuned loops made from wire is their low sensitivity. Rather than using a pre-amp you can boost the output by making the loop larger (e.g., a circumference of 0.1 wavelength or even larger). The larger loop maintains a directional pattern similar to the smaller one but also exhibits a higher radiation radiation resistance and hence lower losses. Good luck with the experiments and let us know how you get on. 73, Brian VK3MI ZL1AZE From: tsho...@wmata.com To: topband@contesting.com Date: Sat, 16 Jun 2012 13:28:38 + Subject: Topband: Receiving loops I want to try a new receiving antenna for the summer Stew Perry. Last winter was my first foray onto 160M and I really felt like an alligator. I could work everyone I could hear, with just 100W. I think that means I need a better receive antenna. If you look at my score in the winter Stew Perry I think I did great QSO-number wise, but my average distance was very poor, I'm guessing typical alligator. I have tried pennants and K9AY's over the winter with little success. Compared to my transmitting antenna (A T with a poor radial system) most signals were still better, S/N wise, on my transmitting antenna. I feel like I must've been doing something wrong. Still the fact that a few signals came in on the loop with by ear much better S/N, maybe I was on the right track and just didn't try hard enough. I will be trying a small tuned magnetic loop tonight (e.g. the last one at http://www.w8ji.com/magnetic_receiving_loops.htm with the 9:1 transformer) . And maybe a terminated beverage but I'm limited to about 150'... well maybe I could run something longer down the driveway as long as I clean it up before the sun comes up and the neighbors see. I was fairly impressed with small tuned magnetic loops when I was doing some BCB DX'ing several years ago. I wasn't comparing with beverages or anything. Tim N3QE ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: full wave horiz loop
EZNEC is your friend. On 6/16/12 9:35 PM, Tom W2MN wrote: A couple of us in the radio club were discussing the possibility of installing a full wave horizontal loop antenna (for Rx and Tx) on top of a building we have access to. The loop would be about 20ft above the building roof, making it about 100ft above ground. The loop could be a rectangle approx. 180ft x 110ft (adjusted for a full wavelength on 160m). We were thinking of using it on 160m as well as 80m. We would use steel / copper clad wire and there in NO possibility of support except at the corners; so it will sag under its own weight. Would appreciate any comments concerning its usefulness. Is it going to be worth the effort?? Tom ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Receiving loops
Receiving antennas are about directivity, not sensitivity. That is the best way to reduce noise although a very small antenna can change the signal to noise ratio without being directional. Sent from my iPad On Jun 17, 2012, at 11:16, W2XJ w...@nyc.rr.com wrote: Sensitivity is not always important. Small loops in general receive less noise and the real exercise is balancing the internal noise floor against the actual signal received. In some cases a loss up to 20 db can be acceptable the numbers are easy enough to run. On 6/16/12 8:17 PM, Brian Miller wrote: Hi Tim I also agree with the previous comments on this thread about detuning the transmit antenna (or any other wires/cables that are resonant on 160M) and isolating the coax feed line from the RX loop. It is also important to identify the direction of the main source of the noise and orientate the loop accordingly so that is being properly nulled. I use a small portable tuned loop to identify the direction of the noise.. Of course, if the noise is coming from the same direction as the DX then you are not going to see much (or any ) improvement in the signal-to-noise ratio. Also, if the noise sources are in multiple directions then it will also be difficult to null the noise properly. I have found that small tuned loops (with their bidirectional nulls) are often more effective in such a situation. One of the problems with small tuned loops made from wire is their low sensitivity. Rather than using a pre-amp you can boost the output by making the loop larger (e.g., a circumference of 0.1 wavelength or even larger). The larger loop maintains a directional pattern similar to the smaller one but also exhibits a higher radiation radiation resistance and hence lower losses. Good luck with the experiments and let us know how you get on. 73, Brian VK3MI ZL1AZE From: tsho...@wmata.com To: topband@contesting.com Date: Sat, 16 Jun 2012 13:28:38 + Subject: Topband: Receiving loops I want to try a new receiving antenna for the summer Stew Perry. Last winter was my first foray onto 160M and I really felt like an alligator. I could work everyone I could hear, with just 100W. I think that means I need a better receive antenna. If you look at my score in the winter Stew Perry I think I did great QSO-number wise, but my average distance was very poor, I'm guessing typical alligator. I have tried pennants and K9AY's over the winter with little success. Compared to my transmitting antenna (A T with a poor radial system) most signals were still better, S/N wise, on my transmitting antenna. I feel like I must've been doing something wrong. Still the fact that a few signals came in on the loop with by ear much better S/N, maybe I was on the right track and just didn't try hard enough. I will be trying a small tuned magnetic loop tonight (e.g. the last one at http://www.w8ji.com/magnetic_receiving_loops.htm with the 9:1 transformer) . And maybe a terminated beverage but I'm limited to about 150'... well maybe I could run something longer down the driveway as long as I clean it up before the sun comes up and the neighbors see. I was fairly impressed with small tuned magnetic loops when I was doing some BCB DX'ing several years ago. I wasn't comparing with beverages or anything. Tim N3QE ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Detuning transmit antenna in receive
If its RF that is a concern the only positive method would be feeding it into a 50/75 Ohm resistor when transmitting. I had to do that some years ago when a Beverage ran between the phased vertical pair and after cooking a few parts in a TS-940. Beverages are now well away from any TX antennas. Carl KM1H - Original Message - From: W2XJ w...@nyc.rr.com To: topband@contesting.com Sent: Sunday, June 17, 2012 11:03 AM Subject: Re: Topband: Detuning transmit antenna in receive There is no single solution for detuning an antenna it depends on electrical length. For verticals a quarter wavelength or less it is common to have a contactor between the network and the radiating element and open the connection to float that element. This is the practice in commercial directional arrays where some tower are not used in a day or night mode. This does not work well on taller towers and I do not know offhand how it would work with the T. It is easy enough to model in EZNEC. On 6/16/12 3:02 PM, Shoppa, Tim wrote: OK, several folks came back and recommended detuning my transmit antenna in receive. Certainly any receive antenna I have is going to be in the shadow of my transmit antenna, a 130-foot flat-top about 85 feet up, fed against ground. (Really it's an 80 meter doublet fed with ladder line. I tie the ladder line together at the bottom and feed against ground.) Trying to figure out what detune is. I match the transmit antenna to 50 ohm coax with a L network at the bottom. If I want to detune, then I can open up the connection between the antenna and the L network at the bottom? Unhook the L or C in the L network? Short out the antenna where it comes into the L network? I could rig up a relay contact to do any of those. Tim N3QE ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1424 / Virus Database: 2433/5075 - Release Date: 06/17/12 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: golden ear award
NO3M, 2,136 miles away from my station, after about 30 repeats correctly received my call and message. An operating technique usually not spoken of, is not transmitting back until everything is correctly or (thought correctly) received. I first was aware of this technique when i was operating from a BB in Canterbury as M/W7DRA/P. An HA3 (I can't remember the whole call) sent a ? and about 5 minutes later of me sending my call in groups of 3 he got my call correct, and then we started on the message. this technique flies in the face of the Rate King (or maybe it should be called the rate monkey on my back?) Once an acknowledgement is made, a super human effort is put forth to complete the contact Thanks to the wisdom of the QRZ locator, I see the summer stew station to station mileage distance for my 8 contacts. 2136, 825, 633, 293, 220, 119, 111, 12. mike w7dra 53 Year Old Mom Looks 33 The Stunning Results of Her Wrinkle Trick Has Botox Doctors Worried http://thirdpartyoffers.juno.com/TGL3141/4fde0ad8d798c60932fst04vuc ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Stew Perry Log Submittal
I've been trying to submit my log to t...@contesting.com as specified in the rules. It keeps getting rejected ... is it such that they don't want the logs from the warm-ups? 73 Dwight NS9I ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Stew Perry Log Submittal
Naw - nothing that sinister. I was going to get to this before the contest - but life events sort of overtook my free time and I didn't get to it. QRX a few days (which is why you didn't hear K7RAT on this time). We'll get it fixed. Tree On Sun, Jun 17, 2012 at 10:10 AM, DGB ns9i2...@bayland.net wrote: I've been trying to submit my log to t...@contesting.com as specified in the rules. It keeps getting rejected ... is it such that they don't want the logs from the warm-ups? 73 Dwight NS9I ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Receiving loops
Thanks. I wasn't referring to a magnetic loop that uses the shield for pickup. I was referring to the outer shield on the coax that runs from any antenna to the shack. If you use an antenna that was chosen for its specific directional and/or low-noise properties, and you don't isolate that antenna from the outer shield of the feedline, the shield itself becomes part of the antenna, spoils the directionality and picks up additional noise. Art DelibertKB3FJO From: w...@aol.com Date: Sun, 17 Jun 2012 11:52:38 -0400 To: radio7...@msn.com CC: topband@contesting.com; tsho...@wmata.com Subject: Re: Topband: Receiving loops If you are referring to a magnetic loop the problem is not the pickup from the shield - that is the conductor for picking up the signals - all signals including noise. The issue with a magnetic loop would be imbalance and that would be due to improper construction where the sides of the loop either way of the gap would not be equal or how you connect or install the tuning capacitor. Close proximity to a conducting surface would also affect the directivity. But even with a poorly constructed mag loop you should still get the null but it may not be symetrical or as deep as it should be. Sent from my iPad On Jun 16, 2012, at 10:36, Arthur Delibert radio7...@msn.com wrote: Tim -- If the suggestions from others don't entirely do the trick, here's another thing to consider: The outer conductor on your coax might be picking up local noise and/or destroying the pattern of your receiving antenna. I DX the AM broadcast band with whatever antennas I can fit into my suburban backyard. I was getting poor results with a pennant until I put Radio Works T-4 line isolators at both ends of the coax. Suddenly the antenna began to behave as expected. Hope this helps. Art DelibertKB3FJO From: tsho...@wmata.com To: topband@contesting.com Date: Sat, 16 Jun 2012 13:28:38 + Subject: Topband: Receiving loops I want to try a new receiving antenna for the summer Stew Perry. Last winter was my first foray onto 160M and I really felt like an alligator. I could work everyone I could hear, with just 100W. I think that means I need a better receive antenna. If you look at my score in the winter Stew Perry I think I did great QSO-number wise, but my average distance was very poor, I'm guessing typical alligator. I have tried pennants and K9AY's over the winter with little success. Compared to my transmitting antenna (A T with a poor radial system) most signals were still better, S/N wise, on my transmitting antenna. I feel like I must've been doing something wrong. Still the fact that a few signals came in on the loop with by ear much better S/N, maybe I was on the right track and just didn't try hard enough. I will be trying a small tuned magnetic loop tonight (e.g. the last one at http://www.w8ji.com/magnetic_receiving_loops.htm with the 9:1 transformer) . And maybe a terminated beverage but I'm limited to about 150'... well maybe I could run something longer down the driveway as long as I clean it up before the sun comes up and the neighbors see. I was fairly impressed with small tuned magnetic loops when I was doing some BCB DX'ing several years ago. I wasn't comparing with beverages or anything. Tim N3QE ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Stew Perry Log Submittal
I actually did bang away at the key off and on for a couple last eve after midnight...nothing heard or worked. Receiving loop, and flat-top 80 M dipole at 70' with the twin-lead shorted and fed against elevated radials. Perpetual daylight in Interior Alaska may have had some effect. That, and no relatively close Rat ops or locals led to a slow eve. It's been 47 years since I've seen stars during a June summer's eve. That's KL7 for you at BP64. 73, Gary NL7Y Naw - nothing that sinister. I was going to get to this before the contest - but life events sort of overtook my free time and I didn't get to it. QRX a few days (which is why you didn't hear K7RAT on this time). We'll get it fixed. Tree ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Detuning transmit antenna in receive
I am very interested in this subject, I am trying to figure out how to detune my 160 inverted L.I am using a flag antenna for receive and unfortunately it is only about 50 feet from the base of the L.By itself the flag works very well at reducing the local electrical noise, (which luckily it is coming from only one direction) When the L is strung up it the flag is useless, it reradiates the noise like mad. I'm hoping to learn more solutions on detuning xmit antennas during receive from the group. Wouldn't it be nice if all we had to do was ground the feedline to the xmit antenna during receive ? sigh I guess the idea is to make the xmit antenna non resonant anywhere near the operating freq during receive. Bob K6UJ On Jun 17, 2012, at 8:03 AM, W2XJ wrote: There is no single solution for detuning an antenna it depends on electrical length. For verticals a quarter wavelength or less it is common to have a contactor between the network and the radiating element and open the connection to float that element. This is the practice in commercial directional arrays where some tower are not used in a day or night mode. This does not work well on taller towers and I do not know offhand how it would work with the T. It is easy enough to model in EZNEC. On 6/16/12 3:02 PM, Shoppa, Tim wrote: OK, several folks came back and recommended detuning my transmit antenna in receive. Certainly any receive antenna I have is going to be in the shadow of my transmit antenna, a 130-foot flat-top about 85 feet up, fed against ground. (Really it's an 80 meter doublet fed with ladder line. I tie the ladder line together at the bottom and feed against ground.) Trying to figure out what detune is. I match the transmit antenna to 50 ohm coax with a L network at the bottom. If I want to detune, then I can open up the connection between the antenna and the L network at the bottom? Unhook the L or C in the L network? Short out the antenna where it comes into the L network? I could rig up a relay contact to do any of those. Tim N3QE ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Detuning transmit antenna in receive
My tower shunt feed for 160 and 80 is latching relay remote controlled. On 160, certain orientations of my very close RX flag result in reduced signal due to the influence of the tuned vertical. In those instances, I detune the shunt by selecting 80m. My amp has a rather dramatic way of reminding me if I fail to switch the shunt back to 160 when transmitting. Just one station's solution. 73 - Steve WB6RSE ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: TX ANT TO RX ANT COUPLING
I have been following the thread with interest. I have a K9AY and a DO loop located within 60 to 75 ft of the TX vertical at our summer home. Interestingly, I find both these antennas very quiet with no sign of noise being coupled to them via the TX antenna. I work a lot of DX from this location on topband using these loops as well as a pair of Beverages, both of which also pass fairly close to my TX vertical and both of which are very quiet. So, why am I not hearing this noise many are experiencing? The TX vertical is a 60 ft toploaded affair and I do not de-tune it on receive. All I have done is to run all the feedlines for both RX antennas and the TX vertical underground in different conduits to a remote switching location. Someone please tell me why I am missing out on all the fun of having noise on my RX antennas. Bill, VE3CSK - No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2180 / Virus Database: 2433/5075 - Release Date: 06/17/12 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: TX ANT TO RX ANT COUPLING
Probably part has to do with the fact that your vertical is 1/8 wavelength and rule of thumb is 1/8 wavelength or less do no have a significant influence unless extremely close. On 6/17/12 5:34 PM, Bill and Liz wrote: I have been following the thread with interest. I have a K9AY and a DO loop located within 60 to 75 ft of the TX vertical at our summer home. Interestingly, I find both these antennas very quiet with no sign of noise being coupled to them via the TX antenna. I work a lot of DX from this location on topband using these loops as well as a pair of Beverages, both of which also pass fairly close to my TX vertical and both of which are very quiet. So, why am I not hearing this noise many are experiencing? The TX vertical is a 60 ft toploaded affair and I do not de-tune it on receive. All I have done is to run all the feedlines for both RX antennas and the TX vertical underground in different conduits to a remote switching location. Someone please tell me why I am missing out on all the fun of having noise on my RX antennas. Bill, VE3CSK - No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2180 / Virus Database: 2433/5075 - Release Date: 06/17/12 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: TX ANT TO RX ANT COUPLING
Sounds like a 1/4 wave vertical to me if its toploaded enough to resonate. Do the radials pass over or under the Beverage? Carl KM1H Carl KM1H - Original Message - From: W2XJ w...@nyc.rr.com To: topband@contesting.com Sent: Sunday, June 17, 2012 5:53 PM Subject: Re: Topband: TX ANT TO RX ANT COUPLING Probably part has to do with the fact that your vertical is 1/8 wavelength and rule of thumb is 1/8 wavelength or less do no have a significant influence unless extremely close. On 6/17/12 5:34 PM, Bill and Liz wrote: I have been following the thread with interest. I have a K9AY and a DO loop located within 60 to 75 ft of the TX vertical at our summer home. Interestingly, I find both these antennas very quiet with no sign of noise being coupled to them via the TX antenna. I work a lot of DX from this location on topband using these loops as well as a pair of Beverages, both of which also pass fairly close to my TX vertical and both of which are very quiet. So, why am I not hearing this noise many are experiencing? The TX vertical is a 60 ft toploaded affair and I do not de-tune it on receive. All I have done is to run all the feedlines for both RX antennas and the TX vertical underground in different conduits to a remote switching location. Someone please tell me why I am missing out on all the fun of having noise on my RX antennas. Bill, VE3CSK - No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2180 / Virus Database: 2433/5075 - Release Date: 06/17/12 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1424 / Virus Database: 2433/5075 - Release Date: 06/17/12 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Summer Stew Results...
I operated about 2 hours in the Stew but enjoyed it to the max. Congratulations to the very patient operators ( esp. N4IS) who copied W1FMR/QRP. I was impressed with the N4IS receiving antenna seen on QRZ.com and his 1/4 wave vertical. Stations that copied my 5w. signal: K2TTT 234.4 mi W6XR 277.7 mi K1GQ 38.7 mi NO3M 452.5 mi VE3TA 465.5 mi K1ZO 71.0 mi K2CBI 192.0 mi VE9HF 292.7 mi W2XL 180.2 mi AB1OD 118.5 mi W3GH 477.1 mi N4IS 1287.8 mi N4PN 986.7 mi VE3OSZ 284.2 mi K1LT 650.0 mi N3QE 427.0 mi K7CS 438.5 mi TX/RX antenna is an inv. L with misc. length radials and progressing slowly on a (K2AV and W0UCE) FCP. 73, Jim / W1FMR - NH ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: TX ANT TO RX ANT COUPLING
Hi Bill The resonance element reradiate noise and also the signal. If you think about why a yagi works, all elements reradiate the signal from the driven elements, but what about on reception, . It is the same. All resonate elements reradiate. Any resonant structure does the same. Here detuning the TX antenna droops the noise by 2 S units on the RX noise. So, why am I not hearing this noise many are experiencing? Noise does no add because it is incoherent, so when you remove one layer you hear start hearing the second layer, there is always noise. But you can hear only to predominant noise the strong one. Detuning a tower is no easy, NX4D 90 FT vertical with top hat is insulated from the ground, Doug was using one vacuum relay to disconnect the tower from the feed line, Doug did it in 2007 however last year he decided to tune a wire tapped 30 FT on the tower, the wire was there because he used to shunt feed the tower. Doug used a capacitor to tune the wire like W8JI explain on his website, guess what, 2 S units down on the noise floor. Now is WF has a really deep null on the sides and RX is much better. On Doug's case some capacitance or something was not right, end even using a detuning relay and floating the tower was not enough to detune the structure, How far the tower can detune your RX antenna,? Well it is easy to see it using EZNEC, one wave far is not enough and on 160m it is over 500ft away. Regards Jose Carlos N4IS - No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2180 / Virus Database: 2433/5075 - Release Date: 06/17/12 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Detuning transmit antenna in receive
The easy way to do that is with a relay between the coax center conductor and the L wire at the feedpoint. When the relay is open, that makes the L a 1/4 wave on 160 which is not self-resonant. The quarter wave is only resonant in conjunction with whatever counterpoise you are using for the L. 73, Guy. On Sun, Jun 17, 2012 at 4:37 PM, Bob K6UJ k...@pacbell.net wrote: I am very interested in this subject, I am trying to figure out how to detune my 160 inverted L.I am using a flag antenna for receive and unfortunately it is only about 50 feet from the base of the L.By itself the flag works very well at reducing the local electrical noise, (which luckily it is coming from only one direction) When the L is strung up it the flag is useless, it reradiates the noise like mad. I'm hoping to learn more solutions on detuning xmit antennas during receive from the group. Wouldn't it be nice if all we had to do was ground the feedline to the xmit antenna during receive ? sigh I guess the idea is to make the xmit antenna non resonant anywhere near the operating freq during receive. Bob K6UJ On Jun 17, 2012, at 8:03 AM, W2XJ wrote: There is no single solution for detuning an antenna it depends on electrical length. For verticals a quarter wavelength or less it is common to have a contactor between the network and the radiating element and open the connection to float that element. This is the practice in commercial directional arrays where some tower are not used in a day or night mode. This does not work well on taller towers and I do not know offhand how it would work with the T. It is easy enough to model in EZNEC. On 6/16/12 3:02 PM, Shoppa, Tim wrote: OK, several folks came back and recommended detuning my transmit antenna in receive. Certainly any receive antenna I have is going to be in the shadow of my transmit antenna, a 130-foot flat-top about 85 feet up, fed against ground. (Really it's an 80 meter doublet fed with ladder line. I tie the ladder line together at the bottom and feed against ground.) Trying to figure out what detune is. I match the transmit antenna to 50 ohm coax with a L network at the bottom. If I want to detune, then I can open up the connection between the antenna and the L network at the bottom? Unhook the L or C in the L network? Short out the antenna where it comes into the L network? I could rig up a relay contact to do any of those. Tim N3QE ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Summer Stew Results...
I ended up with 12 contacts for the whole night not to shabby for 6w ERP from a 7' tall Hi-Q Screwdriver @ 20' w/16 radials ea 13' long. Out of the 12 contacts, 2 were ~400km, 2 were ~600km, 4 were ~1100km, 1 was ~1700km, and 3 were over 2000km. I basically worked every one I could hear, with the exception of a few (4-5) that I heard answering other folks cq's, but never heard them anywhere calling cq themselves. -- GB 73 K5OAI Sam Morgan On 6/17/2012 8:15 PM, Jim F. wrote: I operated about 2 hours in the Stew but enjoyed it to the max. Congratulations to the very patient operators ( esp. N4IS) who copied W1FMR/QRP. I was impressed with the N4IS receiving antenna seen on QRZ.com and his 1/4 wave vertical. Stations that copied my 5w. signal: K2TTT234.4 mi W6XR277.7 mi K1GQ38.7 mi NO3M452.5 mi VE3TA465.5 mi K1ZO 71.0 mi K2CBI192.0 mi VE9HF292.7 mi W2XL 180.2 mi AB1OD 118.5 mi W3GH477.1 mi N4IS 1287.8 mi N4PN986.7 mi VE3OSZ284.2 mi K1LT 650.0 mi N3QE427.0 mi K7CS438.5 mi TX/RX antenna is an inv. L with misc. length radials and progressing slowly on a (K2AV and W0UCE) FCP. 73, Jim / W1FMR - NH ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Summer Stew Results...
translated into miles :-) KB5NJD 245mi WD5R 640mi N7DF 244mi K7CA 800mi N03M1308mi N0TT 650mi W5XZ 359mi KG7H1448mi N3RN1090mi K9YC1321mi NM5S 361mi KI0I 593mi GB 73 K5OAI Sam Morgan On 6/17/2012 9:17 PM, Sam Morgan wrote: I ended up with 12 contacts for the whole night not to shabby for 6w ERP from a 7' tall Hi-Q Screwdriver @ 20' w/16 radials ea 13' long. Out of the 12 contacts, 2 were ~400km, 2 were ~600km, 4 were ~1100km, 1 was ~1700km, and 3 were over 2000km. I basically worked every one I could hear, with the exception of a few (4-5) that I heard answering other folks cq's, but never heard them anywhere calling cq themselves. -- GB 73 K5OAI Sam Morgan On 6/17/2012 8:15 PM, Jim F. wrote: I operated about 2 hours in the Stew but enjoyed it to the max. Congratulations to the very patient operators ( esp. N4IS) who copied W1FMR/QRP. I was impressed with the N4IS receiving antenna seen on QRZ.com and his 1/4 wave vertical. Stations that copied my 5w. signal: K2TTT234.4 mi W6XR277.7 mi K1GQ38.7 mi NO3M452.5 mi VE3TA465.5 mi K1ZO 71.0 mi K2CBI192.0 mi VE9HF292.7 mi W2XL 180.2 mi AB1OD 118.5 mi W3GH477.1 mi N4IS 1287.8 mi N4PN986.7 mi VE3OSZ284.2 mi K1LT 650.0 mi N3QE427.0 mi K7CS438.5 mi TX/RX antenna is an inv. L with misc. length radials and progressing slowly on a (K2AV and W0UCE) FCP. 73, Jim / W1FMR - NH ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Detuning transmit antenna in receive
A previous edition (and maybe the current one) of the Low Band DXing book has several methods of detuning TX antennas...might be worth a look. Some can be done right in the shack. 73 Charlie, N0TT On Sun, 17 Jun 2012 13:37:55 -0700 Bob K6UJ k...@pacbell.net writes: I am very interested in this subject, I am trying to figure out how to detune my 160 inverted L.I am using a flag antenna for receive and unfortunately it is only about 50 feet from the base of the L.By itself the flag works very well at reducing the local electrical noise, (which luckily it is coming from only one direction) When the L is strung up it the flag is useless, it reradiates the noise like mad. I'm hoping to learn more solutions on detuning xmit antennas during receive from the group. Wouldn't it be nice if all we had to do was ground the feedline to the xmit antenna during receive ? sigh I guess the idea is to make the xmit antenna non resonant anywhere near the operating freq during receive. Bob K6UJ On Jun 17, 2012, at 8:03 AM, W2XJ wrote: There is no single solution for detuning an antenna it depends on electrical length. For verticals a quarter wavelength or less it is common to have a contactor between the network and the radiating element and open the connection to float that element. This is the practice in commercial directional arrays where some tower are not used in a day or night mode. This does not work well on taller towers and I do not know offhand how it would work with the T. It is easy enough to model in EZNEC. On 6/16/12 3:02 PM, Shoppa, Tim wrote: OK, several folks came back and recommended detuning my transmit antenna in receive. Certainly any receive antenna I have is going to be in the shadow of my transmit antenna, a 130-foot flat-top about 85 feet up, fed against ground. (Really it's an 80 meter doublet fed with ladder line. I tie the ladder line together at the bottom and feed against ground.) Trying to figure out what detune is. I match the transmit antenna to 50 ohm coax with a L network at the bottom. If I want to detune, then I can open up the connection between the antenna and the L network at the bottom? Unhook the L or C in the L network? Short out the antenna where it comes into the L network? I could rig up a relay contact to do any of those. Tim N3QE ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Summer Stew Results
Top banders, I worked 39 stations in 2 1/2 hours last night. I finished the installation of a K2AV FCP about 6pm, ate supper, and was QRV at z. Conditions here are 70 ft up Inv-L then across 60 ft in two pecan trees and running from 300 to 550w depending on TX frequency, with FCP lowest wire up 8'. I need to lengthen the Inv-L since my resonant freq is currently 1870. Long distance winner for me was VE9HF who answered my cq. Thanks for the qso's. Jim N4DU ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Summer Stew Results...
gosh, thanks, was going to ask, but thought i would look dumb.. mike w7dra On Sun, 17 Jun 2012 21:25:40 -0500 Sam Morgan k5oai@gmail.com writes: translated into miles :-) KB5NJD 245mi WD5R 640mi N7DF 244mi K7CA 800mi N03M1308mi N0TT 650mi W5XZ 359mi KG7H1448mi N3RN1090mi K9YC1321mi NM5S 361mi KI0I 593mi GB 73 K5OAI Sam Morgan On 6/17/2012 9:17 PM, Sam Morgan wrote: I ended up with 12 contacts for the whole night not to shabby for 6w ERP from a 7' tall Hi-Q Screwdriver @ 20' w/16 radials ea 13' long. Out of the 12 contacts, 2 were ~400km, 2 were ~600km, 4 were ~1100km, 1 was ~1700km, and 3 were over 2000km. I basically worked every one I could hear, with the exception of a few (4-5) that I heard answering other folks cq's, but never heard them anywhere calling cq themselves. -- GB 73 K5OAI Sam Morgan On 6/17/2012 8:15 PM, Jim F. wrote: I operated about 2 hours in the Stew but enjoyed it to the max. Congratulations to the very patient operators ( esp. N4IS) who copied W1FMR/QRP. I was impressed with the N4IS receiving antenna seen on QRZ.com and his 1/4 wave vertical. Stations that copied my 5w. signal: K2TTT234.4 mi W6XR277.7 mi K1GQ38.7 mi NO3M452.5 mi VE3TA465.5 mi K1ZO 71.0 mi K2CBI192.0 mi VE9HF292.7 mi W2XL 180.2 mi AB1OD 118.5 mi W3GH477.1 mi N4IS 1287.8 mi N4PN986.7 mi VE3OSZ284.2 mi K1LT 650.0 mi N3QE427.0 mi K7CS438.5 mi TX/RX antenna is an inv. L with misc. length radials and progressing slowly on a (K2AV and W0UCE) FCP. 73, Jim / W1FMR - NH ___ UR RST IS ... ... ..9 QSB QSB - hw? BK Fast, Secure, NetZero 4G Mobile Broadband. Try it. http://www.netzero.net/?refcd=NZINTISP0512T4GOUT2 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
