Re: Topband: Top band dispondant
The answer to this one comes in several parts. Your antenna is composed of a "pole" (the up 40 and out 20) and a "counter-pole" (your elevated loaded radials). Power is DRIVEN into BOTH of these necessarily. Contrary to a dipole (where pole and counter-pole are identical and opposite, and both intended to radiate), usually on 160 the counter-pole is designed to accept power and then give it back dissipating or radiating as little as possible. The design and efficiency of the pole and counter-pole are separate issues, and from my reading of your post (however accurate or not) contain rectifiable problems for either in your case. If the counterpole (raised radials, buried radials, counterpoise) is already well designed for very low loss and very low radiation, it will not figure much into the performance of the pole portion of the antenna. Let's first consider the pole by itself. If the pole is a wire that only goes up 40 and out 20, on 160 the current will be zero at the end of the out 20 wire, and some current level related to power at the feed and a pretty low feed resistance at the feedpoint. Looking at a graphical representation, current will nearly linearly reduce in amplitude going from the feed to zero at the end. With the power related to the square of the current, the first thirty feet of wire will be responsible for radiating 86% of the power. The highest current will be closest to the ground creating the highest possible ground field losses for that power and length of wire. And since the highest possible current will be at the feed, therefore the highest possible current will be going into the counterpole, creating the highest possible counterpole ground field loss for that power, for that counterpole design and length of radiator. In your design the feedpoint is only 40 degrees from the current zero at the end of the wire. If instead we do something folded-wire at the end of the out 20 wire to get the feed point at 110 degrees from end-of-wire, then the current max will be in the middle of your radiating wire and current almost evenly distributed over the radiating wire. This will reduce feedpoint current to 0.59 times previous value, and multiply true feed R by 2.86. Given that most ham radial systems are NOT dense or or not uniform, the effective series resistance of the radial system is often fairly high compared to commercial radial systems. The radial system's effective series resistance is often in the same range as the radiator's radiation resistance, sometimes greater, and a large portion of drive power is lost in the ground. Multiplying the feed R, by moving the current max off the bottom and up the radiator, lowers the current that has to be driven into the counterpole, and lowers I^2*R losses in the ground. The COMBINATION of a 5/16 wave single wire folded counterpoise (FCP) AND top-loading the vertical can make a very large difference. Either one has been known to make a large difference. And since an FCP is so much more compact than other counterpole alternatives, that aspect may allow you to improve your vertical radiator run. To create a 70 degree top-load, take a 104 foot wire, run it out west 26 feet, then parallel back to the center, then out east 26 feet, then parallel back to the end insulator at the center. This will look very much like a 52' folded dipole without a feedline. You just take the top of the up 40 out 20 main vertical wire and attach to one side of the folded dipole feedpoint. Leave the other side of the folded dipole feedpoint open and insulated as the end of the overall wire. The top load folded dipole can have the ends droop down 45 degrees, like an inverted vee folded dipole, without any ill effects. The radiation from the top load tends to cancel out. 450 ohm open wire ladder line would be ideal for this. Use of the 360-400 ohm PE sheathed "450" window line (Wireman #554, etc) MAY have some loss associated with its use.I have no data on that. Use of Wireman #554 with a threaded center third conductor for FCP construction did prove lossy. The top load WILL be carrying the same current at the FCP but will not have the threaded third wire in the center. FCP construction and material details for the required isolation transformer may be found at w0uce.net/K2AVantennas.html People ARE making significant improvements in 160 performance on building lots once deemed too small for 160, and absolutely too small for radials. In general, use of a 70 degree reduced or no radiation top-load will elevate the current maximum to an optimum height for any vertical size up to 110 degrees. It's chief advantages are to 1) reduce ground field induction losses, and 2) improve low angle skywave radiation. I have finally figured out ways to make this visible at least in NEC4 based models. 73, Guy. On Thu, Feb 2, 2012 at 1:31 AM, kd1ia wrote: > HI all, I have had a rocky relationship with TOPBAND that has never really > blossomed. My QTH is small
Topband: OQRS
Fellow denizens I was just sending for TN2T QSLs via OQRS. A donation question arose due to the way I did this. I sent a TN2T donation on 17 Jan. Then, to complete the OQRS QSL process, today I sent another donation. It feels to me like the 17 Jan donation went directly to TN2T while today's went to fund the OQRS system. Heretofore I (perhaps naively) thought they were one and the same. Whatsay y'all? PS: Boo Hoo I only heard TN2T on TB once and nowhere near effective enough to work them. But did score on 80. No matter, except for 40 all new bandmodes. -- 73 Art K6XT~~ Success is going from failure to failure without a loss of enthusiasm. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: 2Wire, Inc. 3800HGV-B Gateway. RFI --Problem fixed for now….
The CAT5 in question for the interference is the INPUT side of the gateway box. This is sometimes used from the loop termination on the side of the house somewhere to the gateway box. THAT was the CAT5 sensitive to the ferrites. Ethernet on the output side of the gateway has not been an issue. Just the input where the content is 0.2 to 8 point something MHz. On Sat, Feb 4, 2012 at 10:57 AM, Frank Davis wrote: > In reply to Jim: > > The CAT5 cable used with the 3800 modem is the one that came in the box > with it. The cable is very small diameter and very flexible...the modular > plugs on it are smaller then the other plugs I have here on what i call > regular CAT5 cable. The regular CAT5 modular plugs will not plug unto the > jack on the modem. > When that small flexible cable was wound on the two stacked toroids that > I used It was twisted in a couple of places so maybe that contributed to > the FEC events being seen by the telco test equipment. The cable appears > to be very cheap and a minimal attempt by the manufacturer to provide a > cable for general use ...certainly not robust. > > The toroids are not on this line now and all seems to be working fine. > The iMAc download speed testing within the BellAliant network is 6.6 mbps. > The full capacity of the line is supporting 4 IPTV set-top boxes two of > which are HD. > > Fibre Op coming within a few months to my area! > > Frank VO1HP > > > The BellAliant technician told me that placing the ferrites on the CAT5 > > feeding the modem caused a significant number ( hundreds of '000's on a > > continual basis.) of FEC (forward error correction) events to begin > happening > > on my line. > > That does not make sense unless the CAT5 was mechanically distorted by > the winding. That would disturb the impedance at bit, but a LOT of > errors doesn't make sense to me. The ferrites form a common mode choke, > which the differential circuit should not see. > > ___ > UR RST IS ... ... ..9 QSB QSB - hw? BK > ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: 2Wire, Inc. 3800HGV-B Gateway. RFI --Problem fixed for now..
The problems with the 2-Wire corp's 3800 are that even WITH the degree of suppression afforded by twisted pair, if a 1.5 kW 160/80/40 signal (which is IN BAND to the 3800) is around, that the depth of forward error correction is not enough to keep up with the errors that are unavoidable. There are many, many signals which get into the signal and cause errors, lightning static from strikes within a few miles, junk on other telco cable pairs, on and on. The 3800 here was getting 100% correction on what the AT&T guys called an absolutely sh*tty loop from the pole. It had about a half dozen splices, zero shield continuity, was terminated in a pole box with decades old carbon lightning protectors. My neighbor's line had about ten splices in it, and was in worse shape. BUT the forward error correction took all that cr*p and made the result perfect HD + internet + IP phone. 1500 watts of 1.825 to an efficient antenna took it down. They completely repaired the loop and bypassed the old stuff in the cable termination box. They said they used the "good" stuff for the loop for this problem since it was so severe. I don't know what "good stuff" meant. 1.5 kW 160m still took down both our gateways. The break point was about 300-400 watts. The 3801 fixed it all. The 3801 gateway has about 100 times the cache and can delay output far longer, allowing the FEC to work through it all the first time and start disabling sub-carriers. When I'm done with the CQ160 SSB, the 3801 has turned off all the subcarriers from 1.7 to 2.1 and it's not even showing CORRECTED errors beyond the volume of misc stuff it handles all day long. Weekly operation on 160/80/40 will keep a collection of affected subcarriers turned off, and they will gradually come back if operation ceases. Each subcarrier has a data rate that is managed by the 38xx, it knows the point where each individual subcarrier goes into errors, for whatever reason, rolloff, noise, interference, AM BC carriers, hams, whatever. The management is dynamic and goes on all the time. An error on a subcarrier causes an individual subcarrier retest. Massive lengthy pervasive errors can cause something called a retrain, where the whole thing restarts and tests all subcarriers. Pretty clever box if you ask me. It just heals around stuff that gets in. A close lightning strike will cause it to lose sync, because the induced noise is so broadband. Four active channels of HDTV + 18 MB Internet + IP phone. Over crappy copper pairs. Awesome technical accomplishment. 73, Guy. On Sat, Feb 4, 2012 at 1:38 PM, Jim Brown wrote: > On 2/4/2012 8:13 AM, ZR wrote: > > Im running 250' of shielded CAT5 from house to equipment trailer where > the > > router resides and then another 120' up the tower to the 5.8GHz link. > > The issues, Carl, are not with CAT5, shielded or unshielded, but rather > with the equipment on either end, which can generate RF trash or be > susceptible to RF trash. Some commonly used Ethernet products produce > birdies on the HF bands (a couple of frequencies on 30M, around 14,030, > 21,052, the low end of 10M, the low end of 6M are places I hear them, > and there are others). Some digital equipment produces loud broadband > hash. I've seen some POE stuff used with data links at tower sites that > were quite noisy on the MF and HF bands. This trash gets radiated > several ways -- usually most strongly from common mode current on the > Ethernet and power supply cables (or coax if it's used), and often > directly from wiring internal to unshielded boxes. > > Ferrite chokes can greatly attenuate the common mode part of that. > Using shielded CAT5/6/7 can help if, and only if, the shield is > optimally terminated at both ends (both ends are likely generators of > digital trash). That usually means bonding to the shielding enclosure at > both ends. > > 73, Jim Brown K9YC > ___ > UR RST IS ... ... ..9 QSB QSB - hw? BK > ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: K9AY model
Hi does anyone happen to have an EZNEC (or similar file, source or description) that I can use to model the K9AY loop? I have a 150' distance at my location that I would be tempted to try a phasing arrangement but would like to model first. Thanks. David J Rodman, MD Assistant Clinical Professor Department of Ophthalmology SUNY/Buffalo Office 716-857-8654 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: 2Wire, Inc. 3800HGV-B Gateway. RFI --Problem fixed for now..
On 2/4/2012 8:13 AM, ZR wrote: > Im running 250' of shielded CAT5 from house to equipment trailer where the > router resides and then another 120' up the tower to the 5.8GHz link. The issues, Carl, are not with CAT5, shielded or unshielded, but rather with the equipment on either end, which can generate RF trash or be susceptible to RF trash. Some commonly used Ethernet products produce birdies on the HF bands (a couple of frequencies on 30M, around 14,030, 21,052, the low end of 10M, the low end of 6M are places I hear them, and there are others). Some digital equipment produces loud broadband hash. I've seen some POE stuff used with data links at tower sites that were quite noisy on the MF and HF bands. This trash gets radiated several ways -- usually most strongly from common mode current on the Ethernet and power supply cables (or coax if it's used), and often directly from wiring internal to unshielded boxes. Ferrite chokes can greatly attenuate the common mode part of that. Using shielded CAT5/6/7 can help if, and only if, the shield is optimally terminated at both ends (both ends are likely generators of digital trash). That usually means bonding to the shielding enclosure at both ends. 73, Jim Brown K9YC ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: 2Wire, Inc. 3800HGV-B Gateway. RFI --Problem fixed for now….
Frank, Placing ferrites on the line adds reactance and so changes the impedance of the line at the ferrite. If they didn't add reactance, they wouldn't function as filters. The better they work at reducing interference, the higher the impedance bump they've introduced. The impedance bump causes reflections, which translate into bit-errors. So it's good that you're using CAT-5 cable. The spec for this cable requires that the data and power pairs be twisted and separated from each other by a spline. This goes a long way toward controlling the impedance of each pair and so reducing radiation. CAT-6 cable should be better, but it will still be vulnerable to impedance perturbations when you apply ferrites. I've seen ferrites make Ethernet connections completely unusable. This is the reason I always hope that filters on the DC lead to the modem will do the trick. Or grounding the coax shield. 73, Brad KV5V On Sat, Feb 4, 2012 at 9:57 AM, Frank Davis wrote: > In reply to Jim: > > The CAT5 cable used with the 3800 modem is the one that came in the box with > it. The cable is very small diameter and very flexible...the modular plugs > on it are smaller then the other plugs I have here on what i call regular > CAT5 cable. The regular CAT5 modular plugs will not plug unto the jack on the > modem. > When that small flexible cable was wound on the two stacked toroids that I > used It was twisted in a couple of places so maybe that contributed to the > FEC events being seen by the telco test equipment. The cable appears to be > very cheap and a minimal attempt by the manufacturer to provide a cable for > general use ...certainly not robust. > > The toroids are not on this line now and all seems to be working fine. The > iMAc download speed testing within the BellAliant network is 6.6 mbps. The > full capacity of the line is supporting 4 IPTV set-top boxes two of which are > HD. > > Fibre Op coming within a few months to my area! > > Frank VO1HP > >> The BellAliant technician told me that placing the ferrites on the CAT5 >> feeding the modem caused a significant number ( hundreds of '000's on a >> continual basis.) of FEC (forward error correction) events to begin happening >> on my line. > > That does not make sense unless the CAT5 was mechanically distorted by > the winding. That would disturb the impedance at bit, but a LOT of > errors doesn't make sense to me. The ferrites form a common mode choke, > which the differential circuit should not see. > > ___ > UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: 2Wire, Inc. 3800HGV-B Gateway. RFI --Problem fixed for now..
The fundamental problem with this 2wire box (and the uVerse system and similar types) is that it uses the entire low HF spectrum for transmission. The system is - by design - a receiver across the 160, 80 and 40m ham bands. 73/jeff/ac0c www.ac0c.com alpha-charlie-zero-charlie -Original Message- From: ZR Sent: Saturday, February 04, 2012 10:13 AM To: Frank Davis ; topband@contesting.com Subject: Re: Topband:2Wire, Inc. 3800HGV-B Gateway. RFI --Problem fixed for now.. Im running 250' of shielded CAT5 from house to equipment trailer where the router resides and then another 120' up the tower to the 5.8GHz link. Its bundled with the hardline feedlines, rotor and relay control cables and there has never been a RFI problem there or with the earlier 2.4GHz link.and there are no ferrites involved. There are also several UHF repeaters on the tower as well as 160, 80, 40, and 6M all at 1200W. Maybe Ive just been lucky. Carl - Original Message - From: "Frank Davis" To: Sent: Saturday, February 04, 2012 10:57 AM Subject: Re: Topband: 2Wire, Inc. 3800HGV-B Gateway. RFI --Problem fixed for now.. > In reply to Jim: > > The CAT5 cable used with the 3800 modem is the one that came in the box > with it. The cable is very small diameter and very flexible...the modular > plugs on it are smaller then the other plugs I have here on what i call > regular CAT5 cable. The regular CAT5 modular plugs will not plug unto the > jack on the modem. > When that small flexible cable was wound on the two stacked toroids that > I used It was twisted in a couple of places so maybe that contributed to > the FEC events being seen by the telco test equipment. The cable appears > to be very cheap and a minimal attempt by the manufacturer to provide a > cable for general use ...certainly not robust. > > The toroids are not on this line now and all seems to be working fine. > The iMAc download speed testing within the BellAliant network is 6.6 mbps. > The full capacity of the line is supporting 4 IPTV set-top boxes two of > which are HD. > > Fibre Op coming within a few months to my area! > > Frank VO1HP > >> The BellAliant technician told me that placing the ferrites on the CAT5 >> feeding the modem caused a significant number ( hundreds of '000's on a >> continual basis.) of FEC (forward error correction) events to begin >> happening >> on my line. > > That does not make sense unless the CAT5 was mechanically distorted by > the winding. That would disturb the impedance at bit, but a LOT of > errors doesn't make sense to me. The ferrites form a common mode choke, > which the differential circuit should not see. > > ___ > 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: 2112/4788 - Release Date: 02/04/12 > ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: 2Wire, Inc. 3800HGV-B Gateway. RFI --Problem fixed for now..
Im running 250' of shielded CAT5 from house to equipment trailer where the router resides and then another 120' up the tower to the 5.8GHz link. Its bundled with the hardline feedlines, rotor and relay control cables and there has never been a RFI problem there or with the earlier 2.4GHz link.and there are no ferrites involved. There are also several UHF repeaters on the tower as well as 160, 80, 40, and 6M all at 1200W. Maybe Ive just been lucky. Carl - Original Message - From: "Frank Davis" To: Sent: Saturday, February 04, 2012 10:57 AM Subject: Re: Topband: 2Wire, Inc. 3800HGV-B Gateway. RFI --Problem fixed for now.. > In reply to Jim: > > The CAT5 cable used with the 3800 modem is the one that came in the box > with it. The cable is very small diameter and very flexible...the modular > plugs on it are smaller then the other plugs I have here on what i call > regular CAT5 cable. The regular CAT5 modular plugs will not plug unto the > jack on the modem. > When that small flexible cable was wound on the two stacked toroids that > I used It was twisted in a couple of places so maybe that contributed to > the FEC events being seen by the telco test equipment. The cable appears > to be very cheap and a minimal attempt by the manufacturer to provide a > cable for general use ...certainly not robust. > > The toroids are not on this line now and all seems to be working fine. > The iMAc download speed testing within the BellAliant network is 6.6 mbps. > The full capacity of the line is supporting 4 IPTV set-top boxes two of > which are HD. > > Fibre Op coming within a few months to my area! > > Frank VO1HP > >> The BellAliant technician told me that placing the ferrites on the CAT5 >> feeding the modem caused a significant number ( hundreds of '000's on a >> continual basis.) of FEC (forward error correction) events to begin >> happening >> on my line. > > That does not make sense unless the CAT5 was mechanically distorted by > the winding. That would disturb the impedance at bit, but a LOT of > errors doesn't make sense to me. The ferrites form a common mode choke, > which the differential circuit should not see. > > ___ > 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: 2112/4788 - Release Date: 02/04/12 > ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Broadband RFI fix. Re: 2Wire, Inc. 3800HGV-B Gateway. RFI --Problem fixed for now….
On 2/4/2012 2:02 AM, g3...@onetel.com wrote: > 1. Common mode filter in series with Telco line where it comes in house, > just before ADSL splitter (splitter is a replacement faceplate on BT > mastersocket) > 2. Balanced LPF filter just before router/modem > 3. New router/modem > 4. Ferrite on DC lead That's exactly the right approach. 73, Jim K9YC ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: 2Wire, Inc. 3800HGV-B Gateway. RFI --Problem fixed for now….
In reply to Jim: The CAT5 cable used with the 3800 modem is the one that came in the box with it. The cable is very small diameter and very flexible...the modular plugs on it are smaller then the other plugs I have here on what i call regular CAT5 cable. The regular CAT5 modular plugs will not plug unto the jack on the modem. When that small flexible cable was wound on the two stacked toroids that I used It was twisted in a couple of places so maybe that contributed to the FEC events being seen by the telco test equipment. The cable appears to be very cheap and a minimal attempt by the manufacturer to provide a cable for general use ...certainly not robust. The toroids are not on this line now and all seems to be working fine. The iMAc download speed testing within the BellAliant network is 6.6 mbps. The full capacity of the line is supporting 4 IPTV set-top boxes two of which are HD. Fibre Op coming within a few months to my area! Frank VO1HP > The BellAliant technician told me that placing the ferrites on the CAT5 > feeding the modem caused a significant number ( hundreds of '000's on a > continual basis.) of FEC (forward error correction) events to begin happening > on my line. That does not make sense unless the CAT5 was mechanically distorted by the winding. That would disturb the impedance at bit, but a LOT of errors doesn't make sense to me. The ferrites form a common mode choke, which the differential circuit should not see. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Broadband RFI fix. Re: 2Wire, Inc. 3800HGV-B Gateway. RFI --Problem fixed for now….
When I first went over to broadband a few years ago, only 10 watts on 160m used to make the ADSL2 lose connection, even with a wireless system. The house is fed with an overhead telephone line. Of course it depends on location and systems, but after trying various filters for months and months I fixed it with a combination of measures as follows:- 1. Common mode filter in series with Telco line where it comes in house, just before ADSL splitter (splitter is a replacement faceplate on BT mastersocket) 2. Balanced LPF filter just before router/modem 3. New router/modem 4. Ferrite on DC lead 1. The common mode filter is about 30 turns of a twisted pair stripped from CAT-5 loosely wound on a 1 inch ferrite core (unknown u - maybe RFI suppression type). This really did make a difference in combination with the LPF. (The recommended Type 31 ferrite might be better). 2. The LPF is based on the OZ1CTK design with some small variation of components to optimise BB speed. Passband to 1.2MHz, 35dB attenuation on 1.8MHz. Speed now 3MBit/s with filter. 3. Changing modem/router also made a big difference. New router/modem (Addon NWAR-3670 cost £38) proved much more resistant to RFI than old one. With my old Dynamode modem the filters were only partly effective. I also tried another modem (2 year old Netgear) but it only produced a small improvement, even 100w with filters caused the BB to unlock sometimes. 4. Ferrite on DC lead may not be necessary (I put mine on anyway, not tested effect). John ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
