Topband: Shunt fed tower
I've been reading all of the posts about the 160 shunt feeds... I have a 100 foot 45G tower festooned with monobanders from 80 - 10 meters. Because of the monobanders my 4-wire cage is only 30 feet high. The series capacitor is a 1000 pfd vacuum variable and the shunt capacitor is 2000 pfd (This was necessary to get a good swr). Even with the 4 wire cage the bandwidth is not very wide. However I placed a 12 VDC, 1 RPM motor on the shunt capacitor and I can tune it from the shack remotely. The motor needs to be 1 RPM so you can tune accurately. I got it from Digi-Key and you reverse directions by simply changing the polarity with a DPDT toggle switch. It is made by Cramer in CT. It is # CRA201-ND. A complicated arrangement with limit switches is not necessary. Once you find the correct point on the rotation you simply move around that point to do the tuning. 12 VDC should be applied with a SPST normally open, push-button switch. 73, John, W4NU ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Shunt fed tower
Many shunt-fed, loaded towers on 160 exhibit narrow bandwidth and are difficult to match with a single series capacitor for one simple reason: The gamma rod (shunt wire) is TOO CLOSE to the tower. A few years ago, after struggling with Omega matches in conjunction with MANY trips up my tower, I modeled my system with EZNEC. For me, the sweet spot was to position the gamma rod SEVEN (7) FEET from the tower! For my tower (92 feet of Rohn 45, 8 feet of mast above it, shorty 40 at 97 feet and 4-el. 20-m monobander at 92 feet), the tap point is 57 feet up. My minimum SWR (in a 50-ohm system) at my center frequency is around 1.4:1, but my 2.0:1 SWR bandwidth increased (with no change in my skimpy radial field) to over 75 kHz as a result of my modeling efforts. Having struggled with Omega matches for years before that, the present setup is a joy. One way to get in the ballpark without doing any serious modeling is to think about the gamma matches you've probably seen (and maybe even used) on your 20-meter beams. Very roughly, since 160 meters is 1/8 the frequency of 20 meters, all things being equal, the gamma rod spacing on 160 should be eight times what it is on 20. If your 20-meter gamma rod is 7 or 8 inches from your driven element, that's equivalent to 5 or 6 feet on 160. Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. Construction: My local ACE hardware store stocks 8-foot lengths of angle aluminum, which is what I used for my horizontal tap rod. Their heaviest-duty stock is more than strong enough to support itself plus the top of my gamma rod. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way — I simply steady the top portion while making electrical connection to the tower at the tap point. (The nearest Lowe's has even heavier aluminum stock, but if you're using wire instead of heavy tubing, the ACE stock is plenty strong enough.) The bottom of my gamma rod sits on a single piece of 2x8 pressure-treated lumber from the scrap bin. I use a couple of scrap lengths of 1x2 furring strips between one face of the tower and the gamma rod to maintain spacing along the length of the rod. It ain't pretty, but it works...I apologize to no one about my signal on 160! Bud, W2RU ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Some Success
Question: Is there any penalty for using an Omega match except for a possible slight bandwidth reduction over a LC. CLC or LCL network? (Whatever is appropriate) This also assumes using silver planted flat wound air coils and vacuum caps of the appropriate size. IMHOThere is not much out there that can't beat climbing up and down a tower in the winter. Herb Schoenbohm, KV4FZ On 12/15/2011 7:30 AM, Pete Smith wrote: I would try to find that sweet spot first, because if you're like me, you never will. I have stacked tribanders, a 2-el 40-meter beam and an 80 meter lazy-v array all on one tower. I modeled the thing and found where (supposedly) the 50-ohm point would be. After about 5 trips up and down the tower, without finding anything even remotely close to 50 ohms over a +/- 15 foot range, I gave up and just left the omega match in place. 73, Pete N4ZR ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: T-200 vs. T-300
For those who intend to build the FCP INV. L. with a T-200-2 (or an antenna tuner). Me and a few guys from our club wound different types of baluns and chokes on different material and measured them with a analyser. We found the T-200-2 next to useless below 3 Mhz due to a low AL value (uH/100 turns). The T-200A-2 is a lot better, but still not really good in balancing. You better use ferrites (FT-something) as long as you use moderate power. BUT if you go QRO, you should stick with the iron powder cores. I once replaced the T-200-2 in my homebrew s-match with a ferrite. I changed back the same day, cuz after a few seconds with 750W the ferrite got so hot you would not want to touch it. The T-200-2 runs cool over an entire contest. Next step is to replace it with a T-300A-2. Below you find a list of cores with their corresponding Al Value. You can clearly see that the T-300-2 is even lower than the T-200-2. For the FCP INV L. i think a T-300A-2 or even better a T-400A-2 is best choice, may it be expensive. Core Al Value T-200-2 120 T-200A-2 218 T-225-2 120 T-225A-2 215 T-300-2 114 T-300A-2 228 T-400-2 180 T-400A-2 360 I'm not a technician or rf-specialist and english is not my native language, so please forgive me if my explanations are a bit ragged. Yes, i use a T-200-2 in a tuner, which of course is not the same as an antenna, but my feeling tells me i'm on the right track when i say that a T-200-2 is no good choice for frequencies below 3Mhz, http://toroids.info http://www.qrz.lt/ly1gp/amidon.html -- 73, Martin DM4iM ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: motorized matching caps
I recently increased the height of the tower I shunt feed for 160 to 105'. Presently no antennas on the top only a bit of mast out the top. The 2:1 BW is quite narrow so I decided to try to motorize one of the caps in the omega match. First I used large air variables to get a match. Then measured and found I had a vacuum variable that could be used which was great because they take more rotation of the shaft to change capacitance vs the air variables. I was trying to decide what motor to use and was digging around stuff I had. I found an old broken car power antenna. Opening it I found it had a quite large motor, 12V of course. I used the large wheel that the plastic cable to raise and lower the mast was wound on to adapt to the capacitor. Using the large wheel gave me a slower rotation which turned out to be the perfect speed. Its fast but again, with the vacuum variable it takes more movement so it all turned out well. And, best part, the motor and gearing was FREE! 73 Ron N4XD ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Some Success
I tried finding the sweet spot at this qth C31XR at 90 feet 2 EL xm 240 at 70 feet. Tried every 5 feet between 40 and 70 feet over a 5 day period with no luck either 73 Chet N4FX. -Original Message- From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] On Behalf Of Pete Smith Sent: Thursday, December 15, 2011 6:30 AM To: topband@contesting.com Subject: Re: Topband: Some Success I would try to find that sweet spot first, because if you're like me, you never will. I have stacked tribanders, a 2-el 40-meter beam and an 80 meter lazy-v array all on one tower. I modeled the thing and found where (supposedly) the 50-ohm point would be. After about 5 trips up and down the tower, without finding anything even remotely close to 50 ohms over a +/- 15 foot range, I gave up and just left the omega match in place. 73, Pete N4ZR The World Contest Station Database, updated daily at www.conteststations.com The Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com, spots at telnet.reversebeacon.net, port 7000 AND now at arcluster.reversebeacon.net port 7000 On 12/14/2011 5:26 PM, Bob Garrett wrote: Hello Topbanders, Thanks to everyone who responded to my query for help regarding my shunt fed tower. I did configure an Omega match. I do notice that the BW is much narrower using the Omega match compared to the single series capacitor. Once I get all the to antenna work completed, I will probably look for the sweet spot again and use only the series cap. Until then, the Omega match certainly seems to work. I'm also considering changing out the piece of RG8X that I use for the shunt arm and replacing it with a 3 or 4 wire cage. Any suggestions on spacers to use for configuring the cage? Have a great Holiday and once again, thanks for the collective wisdom. 73, Bob K3UL ___ 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: T-200 vs. T-300
OK, but there is a huge amount of different materials in ferrites too. Which kind of material did you use? I've used -61 material in a lot of high power applications without any problems of them overheating. You barely feel any temperature raise in them at all if for example using them as a UN-UN transformer. I like the FT240-61 core very much, it can handle a lot of power. Mike, SM2WMV (SJ2W) http://www.sj2w.se/contest/ On 2011-12-15 14:10, Martin wrote: For those who intend to build the FCP INV. L. with a T-200-2 (or an antenna tuner). Me and a few guys from our club wound different types of baluns and chokes on different material and measured them with a analyser. We found the T-200-2 next to useless below 3 Mhz due to a low AL value (uH/100 turns). The T-200A-2 is a lot better, but still not really good in balancing. You better use ferrites (FT-something) as long as you use moderate power. BUT if you go QRO, you should stick with the iron powder cores. I once replaced the T-200-2 in my homebrew s-match with a ferrite. I changed back the same day, cuz after a few seconds with 750W the ferrite got so hot you would not want to touch it. The T-200-2 runs cool over an entire contest. Next step is to replace it with a T-300A-2. Below you find a list of cores with their corresponding Al Value. You can clearly see that the T-300-2 is even lower than the T-200-2. For the FCP INV L. i think a T-300A-2 or even better a T-400A-2 is best choice, may it be expensive. Core Al Value T-200-2 120 T-200A-2 218 T-225-2 120 T-225A-2 215 T-300-2 114 T-300A-2 228 T-400-2 180 T-400A-2 360 I'm not a technician or rf-specialist and english is not my native language, so please forgive me if my explanations are a bit ragged. Yes, i use a T-200-2 in a tuner, which of course is not the same as an antenna, but my feeling tells me i'm on the right track when i say that a T-200-2 is no good choice for frequencies below 3Mhz, http://toroids.info http://www.qrz.lt/ly1gp/amidon.html ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: T-200 vs. T-300
A couple rules for toroidal inductors might be useful. To increase the reactance you increase the number of turns -- the inductance goes up approximately the square of the number of turns. To increase the power handling capability you add additional cores to make a stack of cores. This will also help with the inductance since the toroid core AL value is affected by the cross sectional area of the core. I would expect that stacking cores might be the more economic route to the desired result. If you are simply building a an RF choke to prevent feed line common mode RF current you should be using Type 31 material. For really good RF choking at 1.8 MHz you should plan on about six turns through at least five stacked cores of type 31 ferrite 2.4 inches o.d. [60 mm] Such a choke will have about 5000 ohms of impedance, mostly resistive. It will certainly handle 1.5 KW going through the feed line [ if the feed line can handle the power]. See K9CY's online paper discussing such RF chokes. You may also want to check my web site for some measurements of various RF chokes made with type 31 using different numbers of cores and turns. Tod, K0TO Sent from my iPad 2 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Crazy RX antenna Question
I typically use a 1/4 WL inverted L on TB, with 23 or so radials that are NOT in a 360 deg ring around the feed.. they go from about 340-65deg ( even spaced ) and NO more than 60' long. Obviously reception is not great, but when sigs are REALLY super good fore most.. I hear DX...barely. I live in a big city and all their CATV feed is above ground..behind my home running the length of my block ( well over 1000' ) and at about a height of 13' is the CATV feed, here goes the crazy question... Has any one ever tried to use the SHIELD of their CATV house drop.. for a VERY long RX antenna? I do realize other ppl are 'wired in' and that there are CATV amps all along that line..as well as consumer products, TV's ect ect again more curious than anything. On my TS940S I have a RX only port that I could try this on, but dont want to just do it w/o asking the 'been there done that' crowd. Also.. I do not subscribe to Cable TV or Internet or VOIP Service FWIW. Yes I really realize this is a very outlandish question.. but Im very curious, and I dont want to just 'try it' and then damage something. If there is no voltage measurable on the Shield .. would it still possibly damage the rig if I gave it a try? Almost embarrassed to sign this email, DE -Steve Raas N2JDQ ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Shunt fed tower
Vertical antennas have been shunt fed for over 70 years. There is no magic involved. Very few MW verticals are ever resonant and resonance is irrelevant. The only important thing is to match the TX so it is happy. The easiest way to deal with matching is to first model on EZNEC which will give an approximation of where the shunt should be connected and then physically moving the shunt to find the 50 ohm point which should be determined by measurement. Once that is accomplished, measure the J and calculate the necessary C to cancel it. On 12/15/11 10:17 AM, Joe Subich, W4TV wrote: On 12/15/2011 7:27 AM, W2RU - Bud Hippisley wrote: Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. That is true but a 100 foot tower with decent sized 20M monobander or 24 foot boom tribander with the front/back elements grounded and a short 40 meter yagi will most certainly have a natural resonant point below 1.8 MHz. Additional side mounted yagis will further lower the resonant point. A tower with resonant point below 1.8 MHz will have a higher impedance which will transform badly in a gamma with high element to rod ratio and narrow spacing. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way — I simply steady the top portion while making electrical connection to the tower at the tap point. R and L Electronics (www.randl.com) has insulators for cage dipoles. They are about 3.5 OD with 12 1/4 holes on a roughly 3 diameter and make excellent insulators for a fat gamma rod. One can use 3, 4, or 6 wires in the cage and achieve effective diameters between 2 and 3 inches. 73, ... Joe, W4TV On 12/15/2011 7:27 AM, W2RU - Bud Hippisley wrote: Many shunt-fed, loaded towers on 160 exhibit narrow bandwidth and are difficult to match with a single series capacitor for one simple reason: The gamma rod (shunt wire) is TOO CLOSE to the tower. A few years ago, after struggling with Omega matches in conjunction with MANY trips up my tower, I modeled my system with EZNEC. For me, the sweet spot was to position the gamma rod SEVEN (7) FEET from the tower! For my tower (92 feet of Rohn 45, 8 feet of mast above it, shorty 40 at 97 feet and 4-el. 20-m monobander at 92 feet), the tap point is 57 feet up. My minimum SWR (in a 50-ohm system) at my center frequency is around 1.4:1, but my 2.0:1 SWR bandwidth increased (with no change in my skimpy radial field) to over 75 kHz as a result of my modeling efforts. Having struggled with Omega matches for years before that, the present setup is a joy. One way to get in the ballpark without doing any serious modeling is to think about the gamma matches you've probably seen (and maybe even used) on your 20-meter beams. Very roughly, since 160 meters is 1/8 the frequency of 20 meters, all things being equal, the gamma rod spacing on 160 should be eight times what it is on 20. If your 20-meter gamma rod is 7 or 8 inches from your driven element, that's equivalent to 5 or 6 feet on 160. Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. Construction: My local ACE hardware store stocks 8-foot lengths of angle aluminum, which is what I used for my horizontal tap rod. Their heaviest-duty stock is more than strong enough to support itself plus the top of my gamma rod. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way — I simply steady the top portion while making electrical connection to the tower at the tap point. (The nearest Lowe's has even heavier aluminum stock, but if you're using wire instead of heavy tubing, the ACE stock is plenty strong enough.) The bottom of my gamma rod sits on a single piece of 2x8 pressure-treated lumber from the scrap bin. I use a couple of scrap lengths of 1x2 furring strips between one face of the tower and the gamma rod to maintain spacing along the length of the rod. It ain't pretty, but it works...I apologize to no one about my signal on 160! Bud, W2RU ___ 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: EF Johnson capacitor specifications
Would any one have an old EF Johnson catalog and could inform me of the specifications for a variable capacitor number 860285-1? Thanks! Julius Julius Fazekas N2WN Tennessee Contest Group http://k4tcg.org/ http://groups.google.com/group/tcg1?hl=en Tennessee QSO Party http://www.tnqp.org/ Elecraft K2 #4455 Elecraft K3/100 #366 Elecraft K3/100 # ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Crazy RX antenna Question
Two things to keep in mind here: 1 - The shield of the CATV drop should be grounded at the entrance to every subscriber along the route as per electrical code. 2 - The shield of the hardline on the poles is bonded to the strand (steel support wire) at each tap and possibly everywhere if it's the bare-aluminum-jacketed kind of hardline. The strand is supposed to be bonded to ground at *every pole*. I think with all those grounds at all kinds of randomly spaced locations you won't get very good antenna performance from the shield, if it receives anything at all. I've never really seen a voltage between the shield of a drop and ground, but you might get a DC ground-loop current. You should, at minimum, capacitively couple to the shield if you want to try using it as a receive antenna. I think the performance will be very poor though if anything at all. You might have better luck seeing if your incoming phone line has any unused pairs available. Depending on how your drop is run, those might work better -- just make sure there is no voltage on them first. Remember also that the big phone cables on the poles are normally shielded, so you're still probably going to get pretty poor performance. You'd also be running a receive antenna right inside a cable with all kinds of weird DSL frequencies so you'd probably get a lot of nasty noise. -Bill KB8WYP I typically use a 1/4 WL inverted L on TB, with 23 or so radials that are NOT in a 360 deg ring around the feed.. they go from about 340-65deg ( even spaced ) and NO more than 60' long. Obviously reception is not great, but when sigs are REALLY super good fore most.. I hear DX...barely. I live in a big city and all their CATV feed is above ground..behind my home running the length of my block ( well over 1000' ) and at about a height of 13' is the CATV feed, here goes the crazy question... Has any one ever tried to use the SHIELD of their CATV house drop.. for a VERY long RX antenna? I do realize other ppl are 'wired in' and that there are CATV amps all along that line..as well as consumer products, TV's ect ect again more curious than anything. On my TS940S I have a RX only port that I could try this on, but dont want to just do it w/o asking the 'been there done that' crowd. Also.. I do not subscribe to Cable TV or Internet or VOIP Service FWIW. Yes I really realize this is a very outlandish question.. but Im very curious, and I dont want to just 'try it' and then damage something. If there is no voltage measurable on the Shield .. would it still possibly damage the rig if I gave it a try? Almost embarrassed to sign this email, DE -Steve Raas N2JDQ ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: T8CC
Anyone on the east coast USA hearing T8CC on Topband? ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Shunt fed tower
Joe, W4TV, Thanks for the info on the insulators. !I just ordered some myself. These are great for making a fat gamma rod as you indicated. (They are a little pricey though, a whopping 35 cents apiece! hihihi) Here is the webpage on RL for these insulators if anybody wants to check it out. http://store.rlham.com/shop/catalog/product_info.php?products_id=66844 73, Bob K6UJ On Dec 15, 2011, at 7:17 AM, Joe Subich, W4TV wrote: On 12/15/2011 7:27 AM, W2RU - Bud Hippisley wrote: Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. That is true but a 100 foot tower with decent sized 20M monobander or 24 foot boom tribander with the front/back elements grounded and a short 40 meter yagi will most certainly have a natural resonant point below 1.8 MHz. Additional side mounted yagis will further lower the resonant point. A tower with resonant point below 1.8 MHz will have a higher impedance which will transform badly in a gamma with high element to rod ratio and narrow spacing. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way — I simply steady the top portion while making electrical connection to the tower at the tap point. R and L Electronics (www.randl.com) has insulators for cage dipoles. They are about 3.5 OD with 12 1/4 holes on a roughly 3 diameter and make excellent insulators for a fat gamma rod. One can use 3, 4, or 6 wires in the cage and achieve effective diameters between 2 and 3 inches. 73, ... Joe, W4TV On 12/15/2011 7:27 AM, W2RU - Bud Hippisley wrote: Many shunt-fed, loaded towers on 160 exhibit narrow bandwidth and are difficult to match with a single series capacitor for one simple reason: The gamma rod (shunt wire) is TOO CLOSE to the tower. A few years ago, after struggling with Omega matches in conjunction with MANY trips up my tower, I modeled my system with EZNEC. For me, the sweet spot was to position the gamma rod SEVEN (7) FEET from the tower! For my tower (92 feet of Rohn 45, 8 feet of mast above it, shorty 40 at 97 feet and 4-el. 20-m monobander at 92 feet), the tap point is 57 feet up. My minimum SWR (in a 50-ohm system) at my center frequency is around 1.4:1, but my 2.0:1 SWR bandwidth increased (with no change in my skimpy radial field) to over 75 kHz as a result of my modeling efforts. Having struggled with Omega matches for years before that, the present setup is a joy. One way to get in the ballpark without doing any serious modeling is to think about the gamma matches you've probably seen (and maybe even used) on your 20-meter beams. Very roughly, since 160 meters is 1/8 the frequency of 20 meters, all things being equal, the gamma rod spacing on 160 should be eight times what it is on 20. If your 20-meter gamma rod is 7 or 8 inches from your driven element, that's equivalent to 5 or 6 feet on 160. Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. Construction: My local ACE hardware store stocks 8-foot lengths of angle aluminum, which is what I used for my horizontal tap rod. Their heaviest-duty stock is more than strong enough to support itself plus the top of my gamma rod. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way — I simply steady the top portion while making electrical connection to the tower at the tap point. (The nearest Lowe's has even heavier aluminum stock, but if you're using wire instead of heavy tubing, the ACE stock is plenty strong enough.) The bottom of my gamma rod sits on a single piece of 2x8 pressure-treated lumber from the scrap bin. I use a couple of scrap lengths of 1x2 furring strips between one face of the tower and the gamma rod to maintain spacing along the length of the rod. It ain't pretty, but it works...I apologize to no one about my signal on 160! Bud, W2RU ___ 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: Crazy RX antenna Question
At 09:34 AM 12/15/2011, Steven Raas wrote: I live in a big city and all their CATV feed is above ground..behind my home running the length of my block ( well over 1000' ) and at about a height of 13' is the CATV feed, here goes the crazy question... Has any one ever tried to use the SHIELD of their CATV house drop.. for a VERY long RX antenna? I actually tried this at a former QTH. The short answer is that it didn't work well. The main reason is that your RX will be OVERWHELMED by TV birdies and many other kinds of CRUD propagating along that line. If you situation is anything like mine was, (and I suspect it will be worse as I lived in a small town), you will see (hear) similar results. When I tried it, all TV's were still analog, so I got very strong horizontal sweep harmonics every 15.9 khz or so all along the band. I don't know what you'll hear now that TV systems have gone digital. Maybe better, maybe worse. One thing you should do, however, is NOT attach your RX directly to the cable. Tap on to it through a 2000pf or larger capacitor so as to block any induced LF AC or DC voltage present on the line. Good luck, 73, Charles - K5ZK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Bev. and power lines.
I would be interested to hear how close any one has put a Beverage to the base of a power line tower (which is radio quiet) before they have started to couple noise in to the receiver. I am not talking about the 11kv or so lines on 30ft wooden poles, but the big 100kv+ 100-150ft towers lines. Have any of you had experience of this? I would obviously never put a Bev. under the lines, but wonder how close subscribers have got and got away with it. Or have had to pull back until the noise has gone. 20m? 50m? 100m? I am aware of the safety issues and have those covered. Thanks for your experiences. Good or bad. Neil G0JHC ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: T8CC
Hello Mike, Here are the last 100 spots for T8CC on the topband, and really not much reported in the US (nothing from the East Coast at all). 73's Don (wd8dsb) N7TK1825.5 T8CC 160M PSE 1145 15 Dec Palau LA3XI 1824.9 T8CC fine operator 2029 14 Dec Palau UA4CR 1824.9 T8CC up 2006 14 Dec Palau NH2T1824.9 T8CC cq qsx UP 1943 14 Dec Palau UA4CR 1825.5 T8CC CQ NA UP1 1446 14 Dec Palau N7TK1825.5 T8CC 160M PSE 1214 14 Dec Palau TF4M1824.0 T8CC was finally getting stronger w 2107 13 Dec Palau DK2CF-@ 1824.0 T8CC up 1.2 tnx QSO 2101 13 Dec Palau SV2GNC 1824.0 T8CC 57 steel cqing up 2035 13 Dec Palau UA4CR 1824.0 T8CC up1-2 1935 13 Dec Palau JA5SWL 1825.0 T8CC CQ UP 1927 13 Dec Palau RU6M1824.0 T8CC QRT? 1909 13 Dec Palau RA3DOX 1824.0 T8CC CLG CQ UP.579 1900 13 Dec Palau UA9YAB-@1824.0 T8CC 599 here 1342 13 Dec Palau JG3IWL 1824.0 T8CC UP 1340 13 Dec Palau W1YY1825.5 T8CC1322 13 Dec Palau JG3IWL 1825.5 T8CC 589 UP1305 13 Dec Palau WL7E1825.5 T8CC up 1 1244 13 Dec Palau IK4NMF-@1824.0 T8CC BIG SIG but you not lsn me :-((( 2041 12 Dec Palau UA4CR 1824.0 T8CC UP 2035 12 Dec Palau LA3XI-@ 1824.0 T8CC up still fine copy 2029 12 Dec Palau JA5BZL 1824.0 T8CC cq up 1936 12 Dec Palau RM8W1824.5 T8CC UP 1350 12 Dec Palau UA4CR 1824.5 T8CC CQ NA UP1 1343 12 Dec Palau JA0SWL 1825.0 T8CC UP 2102 11 Dec Palau JA5SWL 1824.5 T8CC CQ CQ UP 2035 11 Dec Palau 9M2AX 1824.0 T8CC up 1145 11 Dec Palau F5NBU 1825.0 T8CC f8eze deja dans le log stop2021 10 Dec Palau OK2ZAW-@1824.0 T8CC up 1 nice sig tnx 2018 10 Dec Palau JA8SWL 1824.0 T8CC CQ up 2003 10 Dec Palau RA4CC 1824.5 T8CC UP1 op.UA4CC 1619 10 Dec Palau UA9YAB-@1824.6 T8CC1613 10 Dec Palau JA1HGY 1824.5 T8CC CQ up 1609 10 Dec Palau UA0SC 1824.5 T8CC up1 op. UA4CC 1345 10 Dec Palau RZ3DJ-@ 1824.0 T8CC very loud up2 1818 09 Dec Palau OK2WM 1824.0 T8CC cq cq good signal QRT 1814 09 Dec Palau RN1NW-@ 1824.0 T8CC TNX QSO ! Up 1.8 1806 09 Dec Palau OH3GIF-@1824.1 T8CC up21805 09 Dec Palau IK4NMF-@1824.0 T8CC @ UA6A I lsn 579 FB on my beverage 1751 09 Dec Palau UA6A1824.0 T8CC ik4nmf-u never heard tropic ra 1740 09 Dec Palau IK4NMF-@1824.0 T8CC Big sig but no ear 1735 09 Dec Palau RA3DOX 1824.0 T8CC CLG CQ 579 1654 09 Dec Palau RK3ZZ 1824.1 T8CC Nice signal ! 1716 08 Dec Palau LY7M1824.1 T8CC fb signal up1 1658 08 Dec Palau UA9FGJ 1824.0 T8CC up 1 1645 08 Dec Palau F8EZE 1824.0 T8CC nice cpy today 1638 08 Dec Palau RA3DOX 1823.9 T8CC CQ UP. 579 1637 08 Dec Palau JA1ANR 1824.0 T8CC up 1035 08 Dec Palau DK2PH 1824.0 T8CC up, fb sigs, Ark 1844 07 Dec Palau R7NA-@ 1824.1 T8CC UP 1 1843 07 Dec Palau R7NA-@ 1824.1 T8CC UP 2 1839 07 Dec Palau RA3QTT 1824.0 T8CC TNX QSO1800 07 Dec Palau RK3ZZ 1824.0 T8CC CQ-ing
Re: Topband: Crazy RX antenna Question
You will never know without trying. For starters Id suggest a transformer connection to reduce common mode and coax to the house with a floating ground and beads. For a ground on the CATV side try a rod and als the CATV ground, pick what works best. A 259B may be of some help in transformer testing. At the house use a tuner and/or tuneable preselector as the 940 is fussy about input impedance as Ive found out decades agoI still have a pair. Carl KM1H - Original Message - From: Steven Raas sjr...@gmail.com To: topband@contesting.com Sent: Thursday, December 15, 2011 10:34 AM Subject: Topband: Crazy RX antenna Question I typically use a 1/4 WL inverted L on TB, with 23 or so radials that are NOT in a 360 deg ring around the feed.. they go from about 340-65deg ( even spaced ) and NO more than 60' long. Obviously reception is not great, but when sigs are REALLY super good fore most.. I hear DX...barely. I live in a big city and all their CATV feed is above ground..behind my home running the length of my block ( well over 1000' ) and at about a height of 13' is the CATV feed, here goes the crazy question... Has any one ever tried to use the SHIELD of their CATV house drop.. for a VERY long RX antenna? I do realize other ppl are 'wired in' and that there are CATV amps all along that line..as well as consumer products, TV's ect ect again more curious than anything. On my TS940S I have a RX only port that I could try this on, but dont want to just do it w/o asking the 'been there done that' crowd. Also.. I do not subscribe to Cable TV or Internet or VOIP Service FWIW. Yes I really realize this is a very outlandish question.. but Im very curious, and I dont want to just 'try it' and then damage something. If there is no voltage measurable on the Shield .. would it still possibly damage the rig if I gave it a try? Almost embarrassed to sign this email, DE -Steve Raas N2JDQ ___ UR RST IS ... ... ..9 QSB QSB - hw? BK - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1415 / Virus Database: 2108/4082 - Release Date: 12/15/11 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Shunt fed tower
At a prior QTH I had a 90' Rohn 25 with 16' of mast above and stacked 4el W2PV design yagis. The 1/4 wave resonance was 1585 KHz if I remember and the 1 CATV hardline used for a gamma was space 3'. Using an Omega match the 2:1 BW was about 30KHz so I modified the amp to load higher in the band without having to resort to switching relays or motor drive. Voltages were very high at 1200W which required wide spaced bread slicers of 9KV from hamfests and 15KV fixed 857 series caps as padders so I could use low C variables. It worked good enough to win a 160M CW contest, CQ if I remember in 87 or 88. Carl KM1H - Original Message - From: W2RU - Bud Hippisley w...@frontiernet.net To: John Harden jh...@bellsouth.net Cc: topband@contesting.com Sent: Thursday, December 15, 2011 7:27 AM Subject: Re: Topband: Shunt fed tower Many shunt-fed, loaded towers on 160 exhibit narrow bandwidth and are difficult to match with a single series capacitor for one simple reason: The gamma rod (shunt wire) is TOO CLOSE to the tower. A few years ago, after struggling with Omega matches in conjunction with MANY trips up my tower, I modeled my system with EZNEC. For me, the sweet spot was to position the gamma rod SEVEN (7) FEET from the tower! For my tower (92 feet of Rohn 45, 8 feet of mast above it, shorty 40 at 97 feet and 4-el. 20-m monobander at 92 feet), the tap point is 57 feet up. My minimum SWR (in a 50-ohm system) at my center frequency is around 1.4:1, but my 2.0:1 SWR bandwidth increased (with no change in my skimpy radial field) to over 75 kHz as a result of my modeling efforts. Having struggled with Omega matches for years before that, the present setup is a joy. One way to get in the ballpark without doing any serious modeling is to think about the gamma matches you've probably seen (and maybe even used) on your 20-meter beams. Very roughly, since 160 meters is 1/8 the frequency of 20 meters, all things being equal, the gamma rod spacing on 160 should be eight times what it is on 20. If your 20-meter gamma rod is 7 or 8 inches from your driven element, that's equivalent to 5 or 6 feet on 160. Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. Construction: My local ACE hardware store stocks 8-foot lengths of angle aluminum, which is what I used for my horizontal tap rod. Their heaviest-duty stock is more than strong enough to support itself plus the top of my gamma rod. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way — I simply steady the top portion while making electrical connection to the tower at the tap point. (The nearest Lowe's has even heavier aluminum stock, but if you're using wire instead of heavy tubing, the ACE stock is plenty strong enough.) The bottom of my gamma rod sits on a single piece of 2x8 pressure-treated lumber from the scrap bin. I use a couple of scrap lengths of 1x2 furring strips between one face of the tower and the gamma rod to maintain spacing along the length of the rod. It ain't pretty, but it works...I apologize to no one about my signal on 160! Bud, W2RU ___ UR RST IS ... ... ..9 QSB QSB - hw? BK - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1415 / Virus Database: 2102/4081 - Release Date: 12/14/11 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Bev. and power lines.
On Thursday, December 15, 2011 11:44:09 am Neil G0JHC wrote: I would be interested to hear how close any one has put a Beverage to the base of a power line tower (which is radio quiet) before they have started to couple noise in to the receiver. The northeast end of my 30 degree/210 degree two-wire Beverage terminates about 20 feet (horizontal distance) from the 7200 volt (line to neutral) line that runs along the road at the north end of my property. It works great. So far, I've never noticed any coupling (because of proximity) between the Beverages (I have 12 of them - 6 2-wire runs) and any other antenna or metallic object. When there is power line noise, then nearly all of the Beverages hear it, in varying degrees, depending greatly on how close the source is. When the source is very close, almost all of the Beverages hear the noise, and there isn't any discernible difference with regard to the normally preferred direction. When the source is a mile or more away, then the Beverages seem to exhibit their normal directivity. Note that none of my Beverages run parallel to any power lines, except the 90 degree/270 degree Beverage, which is about 500 feet from the power lines. Victor, K1LT ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: T8CC
Not here Mike. T8 is extremely rare, as you know, on the eastern half of North America as there has not been any activity on Topband since KJ9I went there some 13 years ago. Somehow I missed it in 1998. Many people have gone to the two rental QTHs on Palau and failed to put a dent in the need on the Eastern half of NA on Topband. I'm convinced something is wrong with the antennas at those two locations. They seem to work Europe but not many in NA. I sure hope someone can go there and put in a serious effort on Topband, bringing in their own equipment (rigs, amps, antennas, rec antennas, etc.). 73 Bernie Bernie McClenny, W3UR The Daily DX The Weekly DX How's DX 3025 Hobbs Road Glenwood, MD 21738 410-489-6518 Get a free two weeks of The Daily DX and The Weekly DX http://www.dailydx.com/trial.htm The Daily DX on Twitter - http://twitter.com/dailydx -Original Message- From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] On Behalf Of Mike Greenway Sent: Thursday, December 15, 2011 10:55 AM To: TOPBAND Subject: Topband: T8CC Anyone on the east coast USA hearing T8CC on Topband? ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Bev. and power lines.
I have two Flags less than 100 ft from 75 ft high 69kv lines. They are thankfully quiet except for one single insulator bank 1/2 mile away but I can totally null it with the MFJ1025 and a sense antenna right under the lines. I get excellent cardiod patterns on each and the NE facing one points right to the lines. I can fully null out strong NE signals when switching to the SW facing flag and vice versa. However I suspect the 6 1 inch alum lines (3 on each side of the tower) somehow weakens DX levels on 160 overall in the vicinity and only when they are emergized. This is when they are quiet too (the noise from the lousy single insulator bank I mentioned is totally gone in the rain). They turn this line off periodically but mostly in the daylight hours. I am only guessing that the fields around these lines somehow attenuated signal levels because stations not far from me can often hear stuff much louder and many times hear things I simply cannot detect regardless of noise levels being low. I am in hilly terrain however and not out in the open. Sent from my iPad On Dec 15, 2011, at 11:44, Neil G0JHC g0...@blueyonder.co.uk wrote: I would be interested to hear how close any one has put a Beverage to the base of a power line tower (which is radio quiet) before they have started to couple noise in to the receiver. I am not talking about the 11kv or so lines on 30ft wooden poles, but the big 100kv+ 100-150ft towers lines. Have any of you had experience of this? I would obviously never put a Bev. under the lines, but wonder how close subscribers have got and got away with it. Or have had to pull back until the noise has gone. 20m? 50m? 100m? I am aware of the safety issues and have those covered. Thanks for your experiences. Good or bad. Neil G0JHC ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: T-200 vs. T-300
Martin wrote: BUT if you go QRO, you should stick with the iron powder cores. I once replaced the T-200-2 in my homebrew s-match with a ferrite. I changed back the same day, cuz after a few seconds with 750W the ferrite got so hot you would not want to touch it. The T-200-2 runs cool over an entire contest. Next step is to replace it with a T-300A-2. I don't agree with this generalization. I have built many legal limit transformers and baluns with ferrite, and have not had overheating problems. Of course it is necessary to use the correct type of ferrite for the application and the right number of turns on it, etc. It is hard to comment specifically on your anecdotal data on your ferrite failure without additional details. The main misunderstanding I have encountered is that users sometimes choose a ferrite with a very high permeability, but which has a high loss tangent at the frequency of interest. It is often better to use a lower permeability material with a low loss tangent. Although the shunt impedance may not be as high in the latter case, the parallel resistance (Rp) will be much higher and hence the loss will be much lower. Powered iron cores have a very limited permeability range, well below 100. They are cheaper than ferrite cores and can be made to work by using a sufficient number of turns. They are mainly useful for making inductors rather than transformers, because the Al value is more closely specified than ferrite. Also, you want a low Al value when making an inductor because you get improved inductance resolution (since the number of turns must be an integer). Rick N6RK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: T-200 vs. T-300
You are correct Carl, I should have inserted the URL's. My excuse, and it is pretty flimsy, is that I was drafting the reply on my iPad2 which is a bit harder to go off and get links on than my laptop [now being used]. The link to my web site is: http://www.k0to.us/HAM/ham.htm The articles are How to estimate RF Choke impedance and July 24 - RF Choke measurements K9YC's article is: A Ham's Guide to RFI, Ferrites, Baluns, and Audio Interfacing The Cookbook pages are 35 and 36. There is substantial other material worth checking on, but those two pages give information that can be used to go off and buy parts and build. The URL for his article is: www.audiosystemsgroup.com/RFI-Ham.pdf Tod, K0TO -Original Message- From: ZR [mailto:z...@jeremy.mv.com] Sent: Thursday, December 15, 2011 9:04 AM To: Tod - ID; Martin Cc: topband@contesting.com Subject: Re: Topband: T-200 vs. T-300 Some links to that info might help. Carl KM1H ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: T8CC
Since my call appears on the list of T8CC spots below, I guess I should take the opportunity to provide some context. As many know, I'm located in Washington state. When I worked and spotted T8CC on the 13th, Arkady had a good signal, with little or no QSB, and was also hearing well. He called CQ over and over for quite a long time, with few takers (just me, a VK, and some JA's). My antenna is nothing special (a half-sloper, with no separate receiving antenna), so I was surprised there were not more takers. I guess I was in the right place at the right time. I don't know how much longer he will be there, but as I said, he hears well, so if you can hear him, he'll probably hear you. Good luck! 73, Jim W1YY -Original Message- From: Don Kirk Sent: Thursday, December 15, 2011 8:50 AM To: k...@bellsouth.net ; TOPBAND@CONTESTING.COM Subject: Re: Topband: T8CC Hello Mike, Here are the last 100 spots for T8CC on the topband, and really not much reported in the US (nothing from the East Coast at all). 73's Don (wd8dsb) N7TK1825.5 T8CC 160M PSE 1145 15 Dec Palau LA3XI 1824.9 T8CC fine operator 2029 14 Dec Palau UA4CR 1824.9 T8CC up 2006 14 Dec Palau NH2T1824.9 T8CC cq qsx UP 1943 14 Dec Palau UA4CR 1825.5 T8CC CQ NA UP1 1446 14 Dec Palau N7TK1825.5 T8CC 160M PSE 1214 14 Dec Palau TF4M1824.0 T8CC was finally getting stronger w 2107 13 Dec Palau DK2CF-@ 1824.0 T8CC up 1.2 tnx QSO 2101 13 Dec Palau SV2GNC 1824.0 T8CC 57 steel cqing up 2035 13 Dec Palau UA4CR 1824.0 T8CC up1-2 1935 13 Dec Palau JA5SWL 1825.0 T8CC CQ UP 1927 13 Dec Palau RU6M1824.0 T8CC QRT? 1909 13 Dec Palau RA3DOX 1824.0 T8CC CLG CQ UP.579 1900 13 Dec Palau UA9YAB-@1824.0 T8CC 599 here 1342 13 Dec Palau JG3IWL 1824.0 T8CC UP 1340 13 Dec Palau W1YY1825.5 T8CC1322 13 Dec Palau JG3IWL 1825.5 T8CC 589 UP1305 13 Dec Palau WL7E1825.5 T8CC up 1 1244 13 Dec Palau IK4NMF-@1824.0 T8CC BIG SIG but you not lsn me :-((( 2041 12 Dec Palau UA4CR 1824.0 T8CC UP 2035 12 Dec Palau LA3XI-@ 1824.0 T8CC up still fine copy 2029 12 Dec Palau JA5BZL 1824.0 T8CC cq up 1936 12 Dec Palau RM8W1824.5 T8CC UP 1350 12 Dec Palau UA4CR 1824.5 T8CC CQ NA UP1 1343 12 Dec Palau JA0SWL 1825.0 T8CC UP 2102 11 Dec Palau JA5SWL 1824.5 T8CC CQ CQ UP 2035 11 Dec Palau 9M2AX 1824.0 T8CC up 1145 11 Dec Palau F5NBU 1825.0 T8CC f8eze deja dans le log stop2021 10 Dec Palau OK2ZAW-@1824.0 T8CC up 1 nice sig tnx 2018 10 Dec Palau JA8SWL 1824.0 T8CC CQ up 2003 10 Dec Palau RA4CC 1824.5 T8CC UP1 op.UA4CC 1619 10 Dec Palau UA9YAB-@1824.6 T8CC1613 10 Dec Palau JA1HGY 1824.5 T8CC CQ up 1609 10 Dec Palau UA0SC 1824.5 T8CC up1 op. UA4CC 1345 10 Dec Palau RZ3DJ-@ 1824.0 T8CC very loud up2 1818 09 Dec Palau OK2WM 1824.0 T8CC cq cq good signal QRT 1814 09 Dec Palau RN1NW-@ 1824.0 T8CC TNX QSO ! Up 1.8 1806 09 Dec Palau OH3GIF-@1824.1 T8CC up21805 09 Dec Palau IK4NMF-@1824.0 T8CC @ UA6A I lsn 579 FB on my beverage 1751 09 Dec Palau UA6A1824.0 T8CC ik4nmf-u never heard tropic ra 1740 09 Dec Palau IK4NMF-@1824.0 T8CC Big sig but no ear 1735 09 Dec Palau RA3DOX 1824.0 T8CC CLG CQ 579 1654 09 Dec Palau RK3ZZ 1824.1 T8CC Nice signal ! 1716 08
Re: Topband: Shunt fed tower
I direct feed my tower against a sloping radial which works extremely well for me. The highest antenna is at 45m and further down are more monobanders, most side mounted. I do not need any capacitor or coil to tune out reactances and the SWR2 band with is 120kHz, SWR1.15 at 1870kHz. 73 Peter, DJ7WW -Original Message- From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] On Behalf Of Price Smith Sent: Donnerstag, 15. Dezember 2011 19:17 To: 'W2RU - Bud Hippisley'; 'John Harden' Cc: topband@contesting.com Subject: Re: Topband: Shunt fed tower Construction: My local ACE hardware store stocks 8-foot lengths of angle aluminum, which is what I used for my horizontal tap rod. Their heaviest-duty stock is more than strong enough to support itself plus the top of my gamma rod. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way - I simply steady the top portion while making electrical connection to the tower at the tap point. (The nearest Lowe's has even heavier aluminum stock, but if you're using wire instead of heavy tubing, the ACE stock is plenty strong enough.) The bottom of my gamma rod sits on a single piece of 2x8 pressure-treated lumber from the scrap bin. I use a couple of scrap lengths of 1x2 furring strips between one face of the tower and the gamma rod to maintain spacing along the length of the rod. It ain't pretty, but it works...I apologize to no one about my signal on 160! Bud, W2RU From W0RI: Aluminum and Galvanized Steel will set up Galvanic action in time. Those metals DO NOT mix well. You will end up with a battery in time. I have been shunt-feeding my 80 ft of Rohn 45 tower with monobanders for 20, 15 and 10 meters at 80, 90 and 100 ft for over 20 years. For the shunt rod, I use common thin wall 1/2 EMT. I put a 90 degree bend in the top piece at about 5ft from the end, I take a short piece of tubing wrapped with 400 grit sand paper and lightly sand the tower. I coat the rod and the tower with Penetrox and clamp the rod on with stainless hose clamps. My tap is at 35ft and the rod is 30 inches from the tower. I couple the EMT together with standard compression couplers. Coat the rod and the coupling also with Penetrox. I used some RTV on the top side of the couplings. At the base I drove a 1 1/2 dia piece of PVC into the ground and I use black tye-wraps to secure the rod to the PVC pipe. Put a cap on the end of the PVC to prevent water from entering. I use an Omega match with two 500pf Vacuum variables in a 18 x 18 x 6 inch Hammon steel water proof box. It is U-Bolted to the tower about 1 ft from the ground. The rod is connected to the bottom of the box with a large ceramic feed through insulator, using 1 inch braid. At three places I use short pieces of 1/2 inch PVC tubing to stabilize the rod. Use black tye-wraps on the tower and the rod. The 2:1 band with is ~40kHZ. This is enough for me as I operate 99% CW. The center freq is 1830 with a VSWR of 1 to 1. Outside of that freq I can use a NYE MBV-V tuner. I have drawings and an explanation which I will email if anyone wants. Just let me know. 73..Price W0RI ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Bev. and power lines.
Hi Neil My experience with Beverages and other receive antennas near fairly close (~1 mile) to some 400kV power lines was quite depressing. Whenever the weather was damp, misty or raining (or all three simultaneously as this was in England), I basically could hear nothing on 160m on any sort of antenna. Attempts to null the noise were complete failures as there were multiple sources of corona. When the weather was dry everything was fine. The solution was to move about 15 miles from the closest EHV line and later to move 4000 miles over the ocean! 73 Roger VE3ZI/G3RBP ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: T8CC
Thanks Tom for the FB explanation of the situation. Hopefully someone will be encouraged to put T8 on Topband with a real serious effort? It's not a tuff path from NA to T8. It's just like working JA's! 73 Bernie Bernie McClenny, W3UR The Daily DX The Weekly DX How's DX 3025 Hobbs Road Glenwood, MD 21738 410-489-6518 Get a free two weeks of The Daily DX and The Weekly DX http://www.dailydx.com/trial.htm The Daily DX on Twitter - http://twitter.com/dailydx -Original Message- From: DL2OBO [mailto:dl2...@dl2obo.de] Sent: Thursday, December 15, 2011 1:00 PM To: ber...@dailydx.com; 'TOPBAND' Subject: AW: Topband: T8CC I was on Palau in October 2010 on our honeymoon trip. The Palau Pacific Resort * is a great luxury hotel and has a radio room to rent (hotelroom). You can choose from FT1000MP, FT2000 and FT920 plus an automatic Yaesu PA. So far so good. The antennas are not up to date ( Oct. 2010 ).3bander, dipoles warc, 40m GP, 80m dipole, 160m dipole They are on a small hill but there are even more and taller hills towards EU and USA. The Dipole for 160m was broken. Also the complete Coax run up the hill (100m/300ft) is not really in a good shape.(moisture, saltwater environment) I built a 20m tall base loaded vertical to get my signal out on 80m and worked some EU and Westcoast USA. on 160m just a few local JAs.. not really to mention. So if you want THAT LOWBAND qth, choose another rent-a-shack or ask if you can build your own antennas at another place on the very large hotel property. There are better places to put your (lowband) antennas if you get permission from the hotel. The janitor is also a (nonactive) Ham (ex JA) who can assist. He is very helpful. For us, being on honeymoon, there was no chance to put up a topband antenna within a 9 days stay. if you plan ahead and bring some antenna/fishing rods/ the PPR is a great hotel and location if you put up you own low-band antenna. If you want 40% diving, 40% leisure and 20% DX without having to transport radio gear, the Palau and the PPR is heaven on earth! There are at least two more rent-a-shack locations on T8-Palau. links are on my website. The one called Plaza by the sea could be better for 160m, I haven't been there the other one mentioned on www.dl2obo.com is in the city center and has only a shortened dipole for topband or so. No space! many pictures of the hotel(s), surrounding and country are on www.dl2obo.com or quicklinkwww.dl2obo.de/pages/japanpalau/japanpalau.html also DX-meeting with 7J4AAL, JA5AQC, JH1AJT, JA5AUC,. in Hiroshima If you plan a trip to Palau send me an email, maybe I can help with info. getting a license is quick and easy.. DL2OBO (T88DL) Carsten-Thomas Dauer ( Tom ) c/o Hotel Hellers Krug Altendorfer Str. 19 D-37603 Holzminden www.dl2obo.com Ham-Radio www.hotel-hellers-krug.de my hotel / rent-a-shack www.carstendauer.dephotografy -Ursprüngliche Nachricht- Von: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] Im Auftrag von Bernie McClenny, W3UR Gesendet: Donnerstag, 15. Dezember 2011 18:08 An: 'Mike Greenway'; 'TOPBAND' Betreff: Re: Topband: T8CC Not here Mike. T8 is extremely rare, as you know, on the eastern half of North America as there has not been any activity on Topband since KJ9I went there some 13 years ago. Somehow I missed it in 1998. Many people have gone to the two rental QTHs on Palau and failed to put a dent in the need on the Eastern half of NA on Topband. I'm convinced something is wrong with the antennas at those two locations. They seem to work Europe but not many in NA. I sure hope someone can go there and put in a serious effort on Topband, bringing in their own equipment (rigs, amps, antennas, rec antennas, etc.). 73 Bernie Bernie McClenny, W3UR The Daily DX The Weekly DX How's DX 3025 Hobbs Road Glenwood, MD 21738 410-489-6518 Get a free two weeks of The Daily DX and The Weekly DX http://www.dailydx.com/trial.htm The Daily DX on Twitter - http://twitter.com/dailydx -Original Message- From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] On Behalf Of Mike Greenway Sent: Thursday, December 15, 2011 10:55 AM To: TOPBAND Subject: Topband: T8CC Anyone on the east coast USA hearing T8CC on Topband? ___ 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: T8CC
Ulf, DL5AXX, was on 160 as T8XX this last Sept. 221 Top Band Qs. Just 12 with NA. 73 - Steve WB6RSE ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: T-200 vs. T-300
For those building an isolation transformer for a 160M 5/16 FCP -- PLEASE READ! IMPORTANT! Martin has the right instincts, says it feels fishy for this. But it's worse than he thinks. And don't even consider using ferrites. The T300A-2 core and 20 bifilar turns were SPECIFICALLY chosen to produce a residual inductance value in the right order of magnitude to cancel a typical residual capacitive reactance from a 160 meter 5/16 wave single wire folded counterpoise, AND provide enough coupling to make the transformer work, AND maintain a low enough loss to operate QRO without heating, or especially to operate QRP without further handicapping the operator with needless loss. This allows the builder of the simple solution to prune the wire to get resonance and remain somewhere around an ELECTRICAL quarter wave radiator. So this works for T's, L's, U's, straight verticals, 1/8 wave-ish raised radials and HOA miscellaneous stealth wires. A T300 form factor is the minimum to wind 20 bifilar turns on the INSIDE diameter. Twenty turns (forty wires) fills up the inside diameter. Less than the T300A-2's 22.8 A sub L number (Amidon does not use the decimal point) and residual inductance is reduced and doesn't match the FCP. Use of a mu of 20 (#1 material) to pull this off on a smaller form factor with fewer turns adds loss, and gets into heating. FERRITES?? DO NOT use ferrites. This is a transformer, NOT a balun. There is a voltage differential across the winding. The winding will go lossy. We wind up overheating ferrites and cracking. This is not a balun with guaranteed 100% cancelling counter-currents. Powdered iron is required. The Amidon T300A-2 can be replaced with a stacked PAIR of Amidon T300-2, with a SINGLE Micrometals T300-2D, or a stacked PAIR of Micrometals T300-2. You can find the Micrometals cores on eBay. You CAN use the Amidon T400A-2, but that core is forty bux compared to the T300A-2's sixteen, and I haven't figured the correct smaller number of turns to balance the FCP, and since the T300A-2 does the job, why bother to blow 24 bux? Maybe for 5kW RF someone needs to do the work. My specification for results and success of design is predicated on the particular design of isolation transformer. Move away from that and YOU ARE ON YOUR OWN. Further, do not be deceived, to use the 5/16 wave FCP, an isolation transformer is REQUIRED. We ALREADY TRIED using regular balun designs to keep the counterpoise current off the feedline to an FCP. They do not work in this app. Been there, done that. With the wrong kind of dirt under the antenna, using a regular balun goes dummy load on you, merely lossy otherwise. Don't try to feed this with a regular balun and then come back and complain that it didn't work. OF COURSE it didn't work. WE DISCOVERED it wouldn't work. WE TOLD YOU it wouldn't work. Those of you carefully thinking this through could say that you could use a series reactor AND a regular balun. Yeah, yeah, BUT this is now a straight inductor on a core WITHOUT any counter-current to cut down on the losses. So you lose big time on two counts: First, you only saved the cost of 7.5 feet of teflon on wire vs the isolation transformer, because you STILL had to do core+single winding PLUS it also cost you the balun. Second, you lost the fairly high percentage of counter-current cancellation using the bifilar winding in the isolation transformer. So your coil plus regular balun costs you more loss for QRP and heat for QRO. If your beef is that it's too hard to make and get the right materials, Balun Designs is making a model 1142s, which you can buy ready-made, now, and does my full specification without any corner cutting. (I have no financial interest in Balun Designs) http://www.balundesigns.com/servlet/the-108/1-cln-1-High-Isolation-Balun/Detail This is 160 meters, guys. You can't use the miniature stuff down here without going lossy. You're talking about less money than taking the family to a restaurant. Why bother with cheep cheep. 73, Guy K2AV (the inventor) On Thu, Dec 15, 2011 at 8:10 AM, Martin hamra...@vr-web.de wrote: For those who intend to build the FCP INV. L. with a T-200-2 (or an antenna tuner). Me and a few guys from our club wound different types of baluns and chokes on different material and measured them with a analyser. We found the T-200-2 next to useless below 3 Mhz due to a low AL value (uH/100 turns). The T-200A-2 is a lot better, but still not really good in balancing. You better use ferrites (FT-something) as long as you use moderate power. BUT if you go QRO, you should stick with the iron powder cores. I once replaced the T-200-2 in my homebrew s-match with a ferrite. I changed back the same day, cuz after a few seconds with 750W the ferrite got so hot you would not want to touch it. The T-200-2 runs cool over an entire contest. Next step is to replace it with a T-300A-2. Below you find a list of cores with their
Re: Topband: T-200 vs. T-300
Guy Olinger K2AV wrote: Martin has the right instincts, says it feels fishy for this. But it's worse than he thinks. And don't even consider using ferrites. The T300A-2 core and 20 bifilar turns were SPECIFICALLY chosen to produce a residual inductance value in the right order of magnitude to cancel a typical residual capacitive reactance from a 160 meter 5/16 wave single wire folded counterpoise, AND provide enough coupling to make the transformer work, AND maintain a low enough loss to operate QRO without heating, or especially to operate QRP without further handicapping the operator with needless loss. This allows the builder of the simple solution to prune the wire to get resonance and remain somewhere around I'm trying to understand here what is magic about powdered iron. It is true you can't just use any random piece of ferrite. But if the T300A-2 were replaced with LOW PERMEABILITY ferrite having the same permeability as a T300A-2 core, it would produce the required residual inductance. The loss of low permeability ferrite is extremely low, probably lower than powdered iron. Coupling is a function of how the turns are wound, not the core material. Am I missing something? Rick N6RK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: T8CC
Eugene (RA0FF) T88OW has indicated he will be on Palau at the end of December for several weeks and will concentrate on 160 and 80 meters. I sent him information about the antennas at the Pacific Palace needing repair and i ho0pe he gets the information in time to take some wire along for both RX and TX antennas. So far I have not heard a reply but perhaps this will be the chance to finally get T8 on 160. Herb Schoenbohm, KV4FZ On 12/15/2011 1:07 PM, Bernie McClenny, W3UR wrote: Not here Mike. T8 is extremely rare, as you know, on the eastern half of North America as there has not been any activity on Topband since KJ9I went there some 13 years ago. Somehow I missed it in 1998. Many people have gone to the two rental QTHs on Palau and failed to put a dent in the need on the Eastern half of NA on Topband. I'm convinced something is wrong with the antennas at those two locations. They seem to work Europe but not many in NA. I sure hope someone can go there and put in a serious effort on Topband, bringing in their own equipment (rigs, amps, antennas, rec antennas, etc.). 73 Bernie Bernie McClenny, W3UR The Daily DX The Weekly DX How's DX 3025 Hobbs Road Glenwood, MD 21738 410-489-6518 Get a free two weeks of The Daily DX and The Weekly DX http://www.dailydx.com/trial.htm The Daily DX on Twitter - http://twitter.com/dailydx -Original Message- From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] On Behalf Of Mike Greenway Sent: Thursday, December 15, 2011 10:55 AM To: TOPBAND Subject: Topband: T8CC Anyone on the east coast USA hearing T8CC on Topband? ___ 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: Balun Designs FCP Isolation Xfmr Info
Here is a direct link to the Balun Designs FCP Transformer Page. A photo and details will be on my website K2AV antenna page shortly. 73, Jack For those building an isolation transformer for a 160M 5/16 FCP -- PLEASE READ! IMPORTANT! Martin has the right instincts, says it feels fishy for this. But it's worse than he thinks. And don't even consider using ferrites. The T300A-2 core and 20 bifilar turns were SPECIFICALLY chosen to produce a residual inductance value in the right order of magnitude to cancel a typical residual capacitive reactance from a 160 meter 5/16 wave single wire folded counterpoise, AND provide enough coupling to make the transformer work, AND maintain a low enough loss to operate QRO without heating, or especially to operate QRP without further handicapping the operator with needless loss. This allows the builder of the simple solution to prune the wire to get resonance and remain somewhere around an ELECTRICAL quarter wave radiator. So this works for T's, L's, U's, straight verticals, 1/8 wave-ish raised radials and HOA miscellaneous stealth wires. A T300 form factor is the minimum to wind 20 bifilar turns on the INSIDE diameter. Twenty turns (forty wires) fills up the inside diameter. Less than the T300A-2's 22.8 A sub L number (Amidon does not use the decimal point) and residual inductance is reduced and doesn't match the FCP. Use of a mu of 20 (#1 material) to pull this off on a smaller form factor with fewer turns adds loss, and gets into heating. FERRITES?? DO NOT use ferrites. This is a transformer, NOT a balun. There is a voltage differential across the winding. The winding will go lossy. We wind up overheating ferrites and cracking. This is not a balun with guaranteed 100% cancelling counter-currents. Powdered iron is required. The Amidon T300A-2 can be replaced with a stacked PAIR of Amidon T300-2, with a SINGLE Micrometals T300-2D, or a stacked PAIR of Micrometals T300-2. You can find the Micrometals cores on eBay. You CAN use the Amidon T400A-2, but that core is forty bux compared to the T300A-2's sixteen, and I haven't figured the correct smaller number of turns to balance the FCP, and since the T300A-2 does the job, why bother to blow 24 bux? Maybe for 5kW RF someone needs to do the work. My specification for results and success of design is predicated on the particular design of isolation transformer. Move away from that and YOU ARE ON YOUR OWN. Further, do not be deceived, to use the 5/16 wave FCP, an isolation transformer is REQUIRED. We ALREADY TRIED using regular balun designs to keep the counterpoise current off the feedline to an FCP. They do not work in this app. Been there, done that. With the wrong kind of dirt under the antenna, using a regular balun goes dummy load on you, merely lossy otherwise. Don't try to feed this with a regular balun and then come back and complain that it didn't work. OF COURSE it didn't work. WE DISCOVERED it wouldn't work. WE TOLD YOU it wouldn't work. Those of you carefully thinking this through could say that you could use a series reactor AND a regular balun. Yeah, yeah, BUT this is now a straight inductor on a core WITHOUT any counter-current to cut down on the losses. So you lose big time on two counts: First, you only saved the cost of 7.5 feet of teflon on wire vs the isolation transformer, because you STILL had to do core+single winding PLUS it also cost you the balun. Second, you lost the fairly high percentage of counter-current cancellation using the bifilar winding in the isolation transformer. So your coil plus regular balun costs you more loss for QRP and heat for QRO. If your beef is that it's too hard to make and get the right materials, Balun Designs is making a model 1142s, which you can buy ready-made, now, and does my full specification without any corner cutting. (I have no financial interest in Balun Designs) http://www.balundesigns.com/servlet/the-108/1-cln-1-High-Isolation-Balun/Det ail This is 160 meters, guys. You can't use the miniature stuff down here without going lossy. You're talking about less money than taking the family to a restaurant. Why bother with cheep cheep. 73, Guy K2AV (the inventor) On Thu, Dec 15, 2011 at 8:10 AM, Martin hamra...@vr-web.de wrote: For those who intend to build the FCP INV. L. with a T-200-2 (or an antenna tuner). Me and a few guys from our club wound different types of baluns and chokes on different material and measured them with a analyser. We found the T-200-2 next to useless below 3 Mhz due to a low AL value (uH/100 turns). The T-200A-2 is a lot better, but still not really good in balancing. You better use ferrites (FT-something) as long as you use moderate power. BUT if you go QRO, you should stick with the iron powder cores. I once replaced the T-200-2 in my homebrew s-match with a ferrite. I changed back the same day, cuz after a few seconds with 750W the ferrite got so hot you would not want to touch
Topband: FCP Isolation Transformer links
K2AV Antenna Page with details: http://www.w0uce.net/K2AVantennas.html Balun Designs FCP Xfmr Details: http://www.balundesigns.com/servlet/the-108/1-cln-1-High-Isolation-balun/Det ail 73, Jack W0UCE ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Shunt fed tower
I haven't done much modeling in the past.I have a KT36XA which would be very ugly if I had to model it precisely. I also have a linearly loaded 2 el 40M yagi. I suspect that the loading wires probably are negligible in the overall scheme of things at 160M. So I would guess that there some approximation that would give reasonable results as a place to start on the tower. Suggestions? 73, Larry W6NWS - Original Message - From: W2XJ w...@nyc.rr.com To: topband@contesting.com Sent: Thursday, December 15, 2011 10:34 AM Subject: Re: Topband: Shunt fed tower Vertical antennas have been shunt fed for over 70 years. There is no magic involved. Very few MW verticals are ever resonant and resonance is irrelevant. The only important thing is to match the TX so it is happy. The easiest way to deal with matching is to first model on EZNEC which will give an approximation of where the shunt should be connected and then physically moving the shunt to find the 50 ohm point which should be determined by measurement. Once that is accomplished, measure the J and calculate the necessary C to cancel it. On 12/15/11 10:17 AM, Joe Subich, W4TV wrote: On 12/15/2011 7:27 AM, W2RU - Bud Hippisley wrote: Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. That is true but a 100 foot tower with decent sized 20M monobander or 24 foot boom tribander with the front/back elements grounded and a short 40 meter yagi will most certainly have a natural resonant point below 1.8 MHz. Additional side mounted yagis will further lower the resonant point. A tower with resonant point below 1.8 MHz will have a higher impedance which will transform badly in a gamma with high element to rod ratio and narrow spacing. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way — I simply steady the top portion while making electrical connection to the tower at the tap point. R and L Electronics (www.randl.com) has insulators for cage dipoles. They are about 3.5 OD with 12 1/4 holes on a roughly 3 diameter and make excellent insulators for a fat gamma rod. One can use 3, 4, or 6 wires in the cage and achieve effective diameters between 2 and 3 inches. 73, ... Joe, W4TV On 12/15/2011 7:27 AM, W2RU - Bud Hippisley wrote: Many shunt-fed, loaded towers on 160 exhibit narrow bandwidth and are difficult to match with a single series capacitor for one simple reason: The gamma rod (shunt wire) is TOO CLOSE to the tower. A few years ago, after struggling with Omega matches in conjunction with MANY trips up my tower, I modeled my system with EZNEC. For me, the sweet spot was to position the gamma rod SEVEN (7) FEET from the tower! For my tower (92 feet of Rohn 45, 8 feet of mast above it, shorty 40 at 97 feet and 4-el. 20-m monobander at 92 feet), the tap point is 57 feet up. My minimum SWR (in a 50-ohm system) at my center frequency is around 1.4:1, but my 2.0:1 SWR bandwidth increased (with no change in my skimpy radial field) to over 75 kHz as a result of my modeling efforts. Having struggled with Omega matches for years before that, the present setup is a joy. One way to get in the ballpark without doing any serious modeling is to think about the gamma matches you've probably seen (and maybe even used) on your 20-meter beams. Very roughly, since 160 meters is 1/8 the frequency of 20 meters, all things being equal, the gamma rod spacing on 160 should be eight times what it is on 20. If your 20-meter gamma rod is 7 or 8 inches from your driven element, that's equivalent to 5 or 6 feet on 160. Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. Construction: My local ACE hardware store stocks 8-foot lengths of angle aluminum, which is what I used for my horizontal tap rod. Their heaviest-duty stock is more than strong enough to support itself plus the top of my gamma rod. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way — I simply steady the top portion while making electrical connection to the tower at the tap point. (The nearest Lowe's has even heavier aluminum stock, but if you're using wire instead of heavy tubing, the ACE stock is plenty strong enough.) The bottom of my gamma rod sits on a single piece of 2x8 pressure-treated lumber from the scrap bin. I use a couple of scrap lengths of 1x2 furring strips between one face of the tower and the gamma rod to maintain spacing along the length of the rod. It ain't pretty, but it works...I apologize to no one about my signal on 160! Bud, W2RU ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Shunt fed tower
For most of us a precise model is not possible. EZNEC will give you an approximation. The tower is represented as a cylinder equal to the cross section of the real tower. You could measure the existing R and J and then in EZNEC just keep adding loading until EZNEC agrees with your measurements. Then move the shunt wire around in EZNEC until you hit 50 ohms. The result will give you a ballpark but it saves a lot of climbing and rearranged real wires. A yes, to be clear that 50 ohms is at the bottom of the shunt feed. On 12/15/11 4:14 PM, Larry wrote: I haven't done much modeling in the past.I have a KT36XA which would be very ugly if I had to model it precisely. I also have a linearly loaded 2 el 40M yagi. I suspect that the loading wires probably are negligible in the overall scheme of things at 160M. So I would guess that there some approximation that would give reasonable results as a place to start on the tower. Suggestions? 73, Larry W6NWS - Original Message - From: W2XJw...@nyc.rr.com To:topband@contesting.com Sent: Thursday, December 15, 2011 10:34 AM Subject: Re: Topband: Shunt fed tower Vertical antennas have been shunt fed for over 70 years. There is no magic involved. Very few MW verticals are ever resonant and resonance is irrelevant. The only important thing is to match the TX so it is happy. The easiest way to deal with matching is to first model on EZNEC which will give an approximation of where the shunt should be connected and then physically moving the shunt to find the 50 ohm point which should be determined by measurement. Once that is accomplished, measure the J and calculate the necessary C to cancel it. On 12/15/11 10:17 AM, Joe Subich, W4TV wrote: On 12/15/2011 7:27 AM, W2RU - Bud Hippisley wrote: Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. That is true but a 100 foot tower with decent sized 20M monobander or 24 foot boom tribander with the front/back elements grounded and a short 40 meter yagi will most certainly have a natural resonant point below 1.8 MHz. Additional side mounted yagis will further lower the resonant point. A tower with resonant point below 1.8 MHz will have a higher impedance which will transform badly in a gamma with high element to rod ratio and narrow spacing. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way — I simply steady the top portion while making electrical connection to the tower at the tap point. R and L Electronics (www.randl.com) has insulators for cage dipoles. They are about 3.5 OD with 12 1/4 holes on a roughly 3 diameter and make excellent insulators for a fat gamma rod. One can use 3, 4, or 6 wires in the cage and achieve effective diameters between 2 and 3 inches. 73, ... Joe, W4TV On 12/15/2011 7:27 AM, W2RU - Bud Hippisley wrote: Many shunt-fed, loaded towers on 160 exhibit narrow bandwidth and are difficult to match with a single series capacitor for one simple reason: The gamma rod (shunt wire) is TOO CLOSE to the tower. A few years ago, after struggling with Omega matches in conjunction with MANY trips up my tower, I modeled my system with EZNEC. For me, the sweet spot was to position the gamma rod SEVEN (7) FEET from the tower! For my tower (92 feet of Rohn 45, 8 feet of mast above it, shorty 40 at 97 feet and 4-el. 20-m monobander at 92 feet), the tap point is 57 feet up. My minimum SWR (in a 50-ohm system) at my center frequency is around 1.4:1, but my 2.0:1 SWR bandwidth increased (with no change in my skimpy radial field) to over 75 kHz as a result of my modeling efforts. Having struggled with Omega matches for years before that, the present setup is a joy. One way to get in the ballpark without doing any serious modeling is to think about the gamma matches you've probably seen (and maybe even used) on your 20-meter beams. Very roughly, since 160 meters is 1/8 the frequency of 20 meters, all things being equal, the gamma rod spacing on 160 should be eight times what it is on 20. If your 20-meter gamma rod is 7 or 8 inches from your driven element, that's equivalent to 5 or 6 feet on 160. Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. Construction: My local ACE hardware store stocks 8-foot lengths of angle aluminum, which is what I used for my horizontal tap rod. Their heaviest-duty stock is more than strong enough to support itself plus the top of my gamma rod. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way — I simply steady the top portion while making electrical connection to the tower at the tap point. (The
Re: Topband: Shunt fed tower
The tower as a cylinder, 50 ohms at the feed point, etc I knew. Dealing with the yagis was not so clear but your procedure seems like a reasonable and do-able method to deal with it. Thanks 73, Larry W6NWS - Original Message - From: W2XJ w...@nyc.rr.com To: topband@contesting.com Sent: Thursday, December 15, 2011 4:28 PM Subject: Re: Topband: Shunt fed tower For most of us a precise model is not possible. EZNEC will give you an approximation. The tower is represented as a cylinder equal to the cross section of the real tower. You could measure the existing R and J and then in EZNEC just keep adding loading until EZNEC agrees with your measurements. Then move the shunt wire around in EZNEC until you hit 50 ohms. The result will give you a ballpark but it saves a lot of climbing and rearranged real wires. A yes, to be clear that 50 ohms is at the bottom of the shunt feed. On 12/15/11 4:14 PM, Larry wrote: I haven't done much modeling in the past.I have a KT36XA which would be very ugly if I had to model it precisely. I also have a linearly loaded 2 el 40M yagi. I suspect that the loading wires probably are negligible in the overall scheme of things at 160M. So I would guess that there some approximation that would give reasonable results as a place to start on the tower. Suggestions? 73, Larry W6NWS - Original Message - From: W2XJw...@nyc.rr.com To:topband@contesting.com Sent: Thursday, December 15, 2011 10:34 AM Subject: Re: Topband: Shunt fed tower Vertical antennas have been shunt fed for over 70 years. There is no magic involved. Very few MW verticals are ever resonant and resonance is irrelevant. The only important thing is to match the TX so it is happy. The easiest way to deal with matching is to first model on EZNEC which will give an approximation of where the shunt should be connected and then physically moving the shunt to find the 50 ohm point which should be determined by measurement. Once that is accomplished, measure the J and calculate the necessary C to cancel it. On 12/15/11 10:17 AM, Joe Subich, W4TV wrote: On 12/15/2011 7:27 AM, W2RU - Bud Hippisley wrote: Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. That is true but a 100 foot tower with decent sized 20M monobander or 24 foot boom tribander with the front/back elements grounded and a short 40 meter yagi will most certainly have a natural resonant point below 1.8 MHz. Additional side mounted yagis will further lower the resonant point. A tower with resonant point below 1.8 MHz will have a higher impedance which will transform badly in a gamma with high element to rod ratio and narrow spacing. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way — I simply steady the top portion while making electrical connection to the tower at the tap point. R and L Electronics (www.randl.com) has insulators for cage dipoles. They are about 3.5 OD with 12 1/4 holes on a roughly 3 diameter and make excellent insulators for a fat gamma rod. One can use 3, 4, or 6 wires in the cage and achieve effective diameters between 2 and 3 inches. 73, ... Joe, W4TV On 12/15/2011 7:27 AM, W2RU - Bud Hippisley wrote: Many shunt-fed, loaded towers on 160 exhibit narrow bandwidth and are difficult to match with a single series capacitor for one simple reason: The gamma rod (shunt wire) is TOO CLOSE to the tower. A few years ago, after struggling with Omega matches in conjunction with MANY trips up my tower, I modeled my system with EZNEC. For me, the sweet spot was to position the gamma rod SEVEN (7) FEET from the tower! For my tower (92 feet of Rohn 45, 8 feet of mast above it, shorty 40 at 97 feet and 4-el. 20-m monobander at 92 feet), the tap point is 57 feet up. My minimum SWR (in a 50-ohm system) at my center frequency is around 1.4:1, but my 2.0:1 SWR bandwidth increased (with no change in my skimpy radial field) to over 75 kHz as a result of my modeling efforts. Having struggled with Omega matches for years before that, the present setup is a joy. One way to get in the ballpark without doing any serious modeling is to think about the gamma matches you've probably seen (and maybe even used) on your 20-meter beams. Very roughly, since 160 meters is 1/8 the frequency of 20 meters, all things being equal, the gamma rod spacing on 160 should be eight times what it is on 20. If your 20-meter gamma rod is 7 or 8 inches from your driven element, that's equivalent to 5 or 6 feet on 160. Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. Construction: My local ACE hardware store stocks 8-foot lengths of angle aluminum,
Topband: Balun Design FCP XFMR Broken Link Repaired.
http://www.balundesigns.com/servlet/the-108/1-cln-1-High-Isolation-balun/Det ail The link in my previous e-mail was broken - this one works - Sorry Gang. See you in SP this weekend. 73, Jack ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Balun Design FCP XFMR Broken Link Repaired.
Nope Still Broke Wayne W3EA From: w0...@nc.rr.com To: topband@contesting.com Date: Thu, 15 Dec 2011 16:47:42 -0500 Subject: Topband: Balun Design FCP XFMR Broken Link Repaired. http://www.balundesigns.com/servlet/the-108/1-cln-1-High-Isolation-balun/Det ail The link in my previous e-mail was broken - this one works - Sorry Gang. See you in SP this weekend. 73, Jack ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: T8CC
I was on Palau back in '82 as KC6CO. My mission there was the chief radio operator on a USCG cutter that tended the buoys and navigational aids. Some problems I encountered were lack of parts availibility, no tall trees, and extremely rough volcanic rock/soil. I had a big problem getting a good earth ground inland. The only low band antenna I could manage was a random length wire thrown up between the coconut trees. I tossed a wire into the salt water lagoon for a ground. Visions of the WWII coast watchers constantly went through my mind. Not many QSOs were made this way, but I could not get permission to put up anything better. I did have a wonderful visit with Mr. Joe Anson, KC6JA, who was a retired USCG electronics tech who lived there. I lost touch with Joe after a few years. Wonderful diving, boonie stomping, and WWII history. 73 Best DX Charlie WD5BJT See September 2006 CQ Magazine for a published work. www.qsl.net/wd5bjt PeoplePC Online A better way to Internet http://www.peoplepc.com ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: T-200 vs. T-300
You may be right that Micrometals makes most of that stuff and sources Amidon. But these are the individual company product numbers and you have to use the company's own product numbers to order stuff from that given company. You would need to take up Amidon's nomenclature choices with Amidon. Personally I am more annoyed that Amidon uses a different A sub L number scheme than the rest of the world and has their own unique set of formulas. Anyone knows how that came about, that would be interesting to know. 73, Guy. On Thu, Dec 15, 2011 at 3:44 PM, ZR z...@jeremy.mv.com wrote: There is no such thing as an Amidon T-300 or any other toroid. In this case they are just a reseller of Micrometals powered iron products. Carl KM1H - Original Message - From: Guy Olinger K2AV olin...@bellsouth.net To: Martin hamra...@vr-web.de Cc: topband@contesting.com Sent: Thursday, December 15, 2011 2:39 PM Subject: Re: Topband: T-200 vs. T-300 The Amidon T300A-2 can be replaced with a stacked PAIR of Amidon T300-2, with a SINGLE Micrometals T300-2D, or a stacked PAIR of Micrometals T300-2. You can find the Micrometals cores on eBay. You CAN use the Amidon T400A-2, but that core is forty bux compared to the T300A-2's sixteen, and I haven't figured the correct smaller number of turns to balance the FCP, and since the T300A-2 does the job, why bother to blow 24 bux? Maybe for 5kW RF someone needs to do the work. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Balun Design FCP XFMR Broken Link Repaired.
just add the ail on the end of the broken link in your browser GB 73 K5OAI Sam Morgan On 12/15/2011 3:55 PM, Wayne Kline wrote: Nope Still Broke Wayne W3EA From: w0...@nc.rr.com To: topband@contesting.com Date: Thu, 15 Dec 2011 16:47:42 -0500 Subject: Topband: Balun Design FCP XFMR Broken Link Repaired. http://www.balundesigns.com/servlet/the-108/1-cln-1-High-Isolation-balun/Det ail The link in my previous e-mail was broken - this one works - Sorry Gang. See you in SP this weekend. 73, Jack ___ 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: Shunt fed tower
Herb, I tried measuring the tower resonance with a GDO as suggested by ON4UN's book but my GDO wouldn't go low enough in frequency to find resonance. It appears to be below 1.5MHz (100 ft 45G with a KT36XA at 100.5 ft, 80M rotatable dipole at 108 ft, and a 2 el 40M yagi at 117 feet). I was thinking about a 6 wire cage 6 inches in diameter probably about 2-3 feet out but I will rethink that in light the comments by you, Carl. and Guy. It may need to be further out. ON4UN's book suggests an omega match in such circumstances but after measuring with the cage in place I'll see what it actually needs. I am hoping to get a better 160 signal out of the shunt fed tower. I currently have an inverted V that is OK but certainly is not great. I used to have a sloper attached to the 100 foot tower that seemed to work better - most of the time - but it was finicky to tune. I am in the process of putting up another tower which by coincidence(?) is 128 feet from the 100 footer but the new tower is only 70 feet. At some point I will look at phasing them as a 2 el vertical array for 160. The 70 foot tower may a bit short for that service. I need to do some reading and experimenting before I get there though. The line through the towers is pointed right at Europe (NE) or Australia (SE). Thanks all for the comments. 73, Larry W6NWS - Original Message - From: Herb Schoenbohm he...@vitelcom.net To: Larry w6...@arrl.net; TopBand List topband@contesting.com Sent: Thursday, December 15, 2011 5:49 PM Subject: Re: Topband: Shunt fed tower Larry, Because of the complexity of modeling without going crazy, although in simple situations it will get you in the ball park, I would highly recommend a 3 or 4 wire cage space at least 24 inches from the area near the rotor plate on a, let's say, 70 to 80 foot tower. The drop wires should be #8 or #6 copper and tied together in a ring supported by porcelain insulators (PVC not recommended in some circles) around at the base with one wire connected from the ring going to your proposed ATU. With a MFJ bridge measure the feed wire's reactance and impedance against ground. With one climb have your tower climb buddy work his way from the top in 2 foot increments jumpering the cage to the tower with large alligator clips (nothing fancy for this purpose) and tell him or her to keep coming down until you get close to 50 ohms. (It can be 40 to 60 ohms as that is sweet point enough you me) Then back a better connection using split copper bolts with three jumpers to the tower. Whatever the reactance is you can tune out that inductive reactance with an equal value of capacitance. As Guy said forget about the tower being resonant anywhere since in such circumstances you may never get that. A tap coil to ground will get you with a simple L network and series cap should get your SWR to 1:1 even if the sweet point is a bit off. Again the components should be, flat wound coil with correct tap connections, a vac of at least 750pf with broadcast mica paders if required for more C. I have found that single wire shunt feeds are the most problematic to work with, especially when the beams are on multiple levels. A larger diameter cable, if you must only use a single wire shunt can be obtained from using a length of CATV .750 which is 3.5 inch in diameter. But a big shunt doesn't look all that hot and a three wire cage is beautiful, looks like it will work, and in fact does. Good luck, Herb Schoenbohm, KV4FZ On 12/15/2011 5:14 PM, Larry wrote: I haven't done much modeling in the past.I have a KT36XA which would be very ugly if I had to model it precisely. I also have a linearly loaded 2 el 40M yagi. I suspect that the loading wires probably are negligible in the overall scheme of things at 160M. So I would guess that there some approximation that would give reasonable results as a place to start on the tower. Suggestions? 73, Larry W6NWS - Original Message - From: W2XJw...@nyc.rr.com To:topband@contesting.com Sent: Thursday, December 15, 2011 10:34 AM Subject: Re: Topband: Shunt fed tower Vertical antennas have been shunt fed for over 70 years. There is no magic involved. Very few MW verticals are ever resonant and resonance is irrelevant. The only important thing is to match the TX so it is happy. The easiest way to deal with matching is to first model on EZNEC which will give an approximation of where the shunt should be connected and then physically moving the shunt to find the 50 ohm point which should be determined by measurement. Once that is accomplished, measure the J and calculate the necessary C to cancel it. On 12/15/11 10:17 AM, Joe Subich, W4TV wrote: On 12/15/2011 7:27 AM, W2RU - Bud Hippisley wrote: ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: T300A-2
Hello All, I have for sale 2 brand new, still in the plastic seal, T300A-2 Iron Powder Cores from Amidon... Asking $10.00 each plus shipping. 73, Ted K2QMF 53 Year Old Mom Looks 33 The Stunning Results of Her Wrinkle Trick Has Botox Doctors Worried http://thirdpartyoffers.juno.com/TGL3141/4eea8d7a5a22c1d3dbfst02vuc ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Balun Design FCP XFMR Broken Link Repaired
The link works if you manually add the missing letters you did not copy/paste , e.g. ail to the word Detail www.balundesigns.com/servlet/the-108/1-cln-1-High-Isolation-balun/Detail -- 73, Martin DM4iM ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: FCP Isolation Transformer
Would stacked MICROMETALS T300-2/97 work? I thought I saw a thread about what would work ... im mobile and haven't found it yet. Mike KC7NOA From: weeks...@hotmail.com To: w0...@nc.rr.com; topband@contesting.com Date: Thu, 15 Dec 2011 16:18:24 -0600 CC: olin...@bellsouth.net; b...@balundesigns.com Subject: Re: Topband: FCP Isolation Transformer links I probably have SN1 of Bob's Model 1142s transformer. It arrived Priority Mail today. Nice looking unit. I also ordered one of his Model 1116d 1 to 1 high power baluns for another application. Sometime in the next few days I will be putting this transformer on one of my existing inverted L's, along with a FCP and we will see how it goes. Thanks to K2AV and W0UCE for all the work and for sharing the info, and also to Bob at Balun Designs for making this so quickly. One big reason I want to try the FCP is to reduce the footprint of my elevated radials to make more space for rx antennas near the top of my hill. 73 Charlie (Chas) N8RR From: w0...@nc.rr.com To: topband@contesting.com Date: Thu, 15 Dec 2011 15:59:34 -0500 CC: olin...@bellsouth.net; b...@balundesigns.com Subject: Topband: FCP Isolation Transformer links K2AV Antenna Page with details: http://www.w0uce.net/K2AVantennas.html Balun Designs FCP Xfmr Details: http://www.balundesigns.com/servlet/the-108/1-cln-1-High-Isolation-balun/Det ail 73, Jack W0UCE ___ 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: Shunt fed tower
The new tower will have a log periodic on it with a 32 foot boom (IIRC). The new tower will have Phillystran guys as does the 100 foot tower. In Vietnam I use a short MFJ antenna that has a capacity hat that has wires in a X with the a perimeter wire around the X much like what you are describing for some of the AM stations. It actually worked fairly well on 80M for a 20 foot vertical. Thanks again for the insight. 73, Larry W6NWS - Original Message - From: Herb Schoenbohm he...@vitelcom.net To: Larry w6...@arrl.net Sent: Thursday, December 15, 2011 7:17 PM Subject: Re: Topband: Shunt fed tower Larry, i think you found the answer that 100 feet with such a large antenna is in the BC band somewhere. I was surprised how much top loading I got out of my 80 foot tower with a A4S tribander on top alone. A 70 footer is find if you have at least a 30 foot boom on top with either a 20 or 15 meter beam. If you don't plan to use a beam then you can use the top guys connected to the top and put the insulators on each guy at 25 feet, as long as the guy angle is not to acute wherein cancellation will occur. Some AM stations connect a perimeter wire around the point were the top set of guys connect at the insulator. If you do this use power company HV insulators. If you use Johnny Balls for this then use several to avoid flashover with high power. The beauty of the cage is that it can be made by smaller wire since it is what radiates, not the tower. #6 or #8 power company ground wire (that they use at each pole) I have found to be just fine. Put springs of turnbuckles, if you want to avid a bunch of standoffs, at the bottom on the ground side of the bottom insulators. If the tower is to long by virtue of having to much top loading, then building a decoupling cage is possible but a lot of work. You might consider having three 1/4 bottom fed slant wire slopers, individualy selected and the tower will give you some directivety as an a periodic reflector of sorts. If you do this make sure there is a least 5 to 8 feet of distance from the top of the sloper to the actual tower. if not things start to intercouple and matching at the bottom is more problematic. Nice thing about a bottom fed quarter wave sloper, with some nice radials, is that in using three rope halyards you can fine tune the antenna length or if it is to short you can add some series inductance to get the match you want. some stations report about 3 db of increase or decrease when the slopers are switched but the paterrns are broad enough not to produce any deep nuls. Herb, KV4FZ On 12/15/2011 7:45 PM, Larry wrote: Herb, I tried measuring the tower resonance with a GDO as suggested by ON4UN's book but my GDO wouldn't go low enough in frequency to find resonance. It appears to be below 1.5MHz (100 ft 45G with a KT36XA at 100.5 ft, 80M rotatable dipole at 108 ft, and a 2 el 40M yagi at 117 feet). I was thinking about a 6 wire cage 6 inches in diameter probably about 2-3 feet out but I will rethink that in light the comments by you, Carl. and Guy. It may need to be further out. ON4UN's book suggests an omega match in such circumstances but after measuring with the cage in place I'll see what it actually needs. I am hoping to get a better 160 signal out of the shunt fed tower. I currently have an inverted V that is OK but certainly is not great. I used to have a sloper attached to the 100 foot tower that seemed to work better - most of the time - but it was finicky to tune. I am in the process of putting up another tower which by coincidence(?) is 128 feet from the 100 footer but the new tower is only 70 feet. At some point I will look at phasing them as a 2 el vertical array for 160. The 70 foot tower may a bit short for that service. I need to do some reading and experimenting before I get there though. The line through the towers is pointed right at Europe (NE) or Australia (SE). Thanks all for the comments. 73, Larry W6NWS - Original Message - From: Herb Schoenbohmhe...@vitelcom.net To: Larryw6...@arrl.net; TopBand Listtopband@contesting.com Sent: Thursday, December 15, 2011 5:49 PM Subject: Re: Topband: Shunt fed tower Larry, Because of the complexity of modeling without going crazy, although in simple situations it will get you in the ball park, I would highly recommend a 3 or 4 wire cage space at least 24 inches from the area near the rotor plate on a, let's say, 70 to 80 foot tower. The drop wires should be #8 or #6 copper and tied together in a ring supported by porcelain insulators (PVC not recommended in some circles) around at the base with one wire connected from the ring going to your proposed ATU. With a MFJ bridge measure the feed wire's reactance and impedance against ground. With one climb have your tower climb buddy work his way from the top in 2 foot increments jumpering
Re: Topband: T-200 vs. T-300
Hi Rick, No magic. Just the right stuff, for the FCP, anyway. To your particulars, when Jerry Sevick measured various ferrites, he measured the lowest loss at mu=40. This was very low, as was the #2 powdered iron at mu=10, the lowest of the powdered iron formulas. So use of ferrites introduces a significantly reduced number of turns, with a much more coarse granularity of possible inductive values, that has to be worked out to use with the FCP, AND the behavior of the mu=40 core under highly reactive loads is not spec'd by the manufacturer. The ferrite will have far less radiating surface if it does heat up under extreme reactive load, AND the length of the parallel bifilar wires may not be enough to cover 160 with the needed behavior in this app. But my admonition about no ferrites has more to do with my knowing that people have misc T240 and T200 form factor ferrites of ALL KINDS laying around, and want to use the one they just found down in the junk box, which does NOT have the material # or mu marked on it anywhere. And these requests seem to pop up just before a contest, when most hope of getting the correct stuff before contest has gone by the wayside. You will note that I have pounded in Amidon T300A-2 #2 powdered iron toroid or strict equivalent, over and over again. And I get back please, please, please tell me that I can use my junkbox ferrite toroid. But don't hold your breath. In over four years of working with non-resonant antenna solutions on 160, **NONE** of the ferrites we tried to use made it. We burnt or cracked ALL of them at QRO. ALL of them. Really. Ferrite demolition derby. I have a new collection of #31 ferrite stuff, but I use those in low band RFI suppression, not transformers. So I'm NOT going to tell anyone it's OK to use a ferrite toroid for feeding an FCP. Beyond that, what is NOT in doubt is that the #2 powdered iron choice works and works well. The installations where I have been able to run QRO brick on key and quick go check toroid temp have all been stone cold. Anyone has contrary experience please let us know ASAP. We will certainly want to investigate and determine why in one place and why not in another. As to why he made his #2 powdered iron choice, Jerry Sevick W2FMI, covers this convincingly in his book, pages 58-63, which I will NOT try to reproduce on the reflector, as even if I did, I can't pass along the essential graphs, photos and diagrams. (Understanding, Building, and Using Baluns and Ununs -- Theory and Practical Designs for the Experimenter, Jerry Sevick W2FMI, Copyright 2003, CQ Communications, Inc., Hicksville, New York) I have found, over the time that I have been working on top-band issues, that dropping back after blowing something up and consulting W2FMI or his material has been most valuable. Alas, Jerry is a silent key, and I can no longer phone him to further expound upon his choices. He particularly chose the large #2 powdered iron cores for applications with a lot of stress on the core, particularly 160 meters. Some key quotes: Because my simple loss measurements indicated that the higher permeability powdered-irons had more loss than the No. 2 material, I decided to design a 4:1 Ruthroff Balun using this material--but with a larger core and more turns than the McCoy Balun. Although McCoy's design has enjoyed considerable success over the years, I felt that a larger inductive reactance was desirable in order to assure better performance on the lower frequency bands (particularly 160 meters). [Ibid p.59] I knew ... that loss with ferrite materials was related to the voltage drop along the length of the [bifilar winding] and to the ... permeability. Permeabilities of 40 (No. 67 Ferrite) exhibited the lowest loss. ... powdered iron #2 material with a permeability of 10 also showed the very same low loss. Because powdered-iron material has been known to be more rugged and linear than ferrite material, this suggested that other powdered-irons ... should be investigated. ... However all four materials showed a definite lower input impedance than #2 material, ... [Ibid p.59] Sevick had access to all of the ferrites, but did not choose any of them for his monster hang-on-the-back-of-the-tuner 4:1 Balun, especially intended to deal with wild voltages, very reactive loads, etc, and handle them as well on 160 as 80-10. Instead Sevick chose the T400A-2 and #2 powdered iron to lay out there as his personal method. So we've done the same. And everywhere we've used teflon-sleeved #14 double polyimide on the #2 powdered iron cores, bad stuff has just quit happening, they work, and they run stone cold. At various scattered places in the book Sevick talks about all the issues that come to bear on designing an isolation transformer on 160 meters. I may not be able to develop a federal level proof case satisfactory so some, but I am sticking with Mr. Sevick. His guidance has always panned out and explained what was ailing. He
Re: Topband: FCP Isolation Transformer
#97 is the wrong material. You need material #2. #2 has red paint. http://www.ebay.com/itm/MICROMETALS-T300-2-IRON-POWER-TOROID-3-CORE-PAIR-NEW-/130528349950?pt=LH_DefaultDomain_0hash=item1e64188efe#ht_651wt_1104 On Thu, Dec 15, 2011 at 7:30 PM, MIKE DURKIN patriot...@msn.com wrote: Would stacked MICROMETALS T300-2/97 work? I thought I saw a thread about what would work ... im mobile and haven't found it yet. Mike KC7NOA From: weeks...@hotmail.com To: w0...@nc.rr.com; topband@contesting.com Date: Thu, 15 Dec 2011 16:18:24 -0600 CC: olin...@bellsouth.net; b...@balundesigns.com Subject: Re: Topband: FCP Isolation Transformer links I probably have SN1 of Bob's Model 1142s transformer. It arrived Priority Mail today. Nice looking unit. I also ordered one of his Model 1116d 1 to 1 high power baluns for another application. Sometime in the next few days I will be putting this transformer on one of my existing inverted L's, along with a FCP and we will see how it goes. Thanks to K2AV and W0UCE for all the work and for sharing the info, and also to Bob at Balun Designs for making this so quickly. One big reason I want to try the FCP is to reduce the footprint of my elevated radials to make more space for rx antennas near the top of my hill. 73 Charlie (Chas) N8RR From: w0...@nc.rr.com To: topband@contesting.com Date: Thu, 15 Dec 2011 15:59:34 -0500 CC: olin...@bellsouth.net; b...@balundesigns.com Subject: Topband: FCP Isolation Transformer links K2AV Antenna Page with details: http://www.w0uce.net/K2AVantennas.html Balun Designs FCP Xfmr Details: http://www.balundesigns.com/servlet/the-108/1-cln-1-High-Isolation-balun/Det ail 73, Jack W0UCE ___ 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: Bev. and power lines.
Corona noise is near impossible to null even from a single source I've found. Fortunately my offender is spark gap noise causing a specific multi point waveform signature. As I understand it however corona is far more likely at the higher voltages. Also FYI here in the US FCC will not enforce interference rules on corona noise which is why so many power companies are quick to diagnose complaints that way. Sent from my iPhone On Dec 15, 2011, at 2:04 PM, Roger Parsons ve...@yahoo.com wrote: Hi Neil My experience with Beverages and other receive antennas near fairly close (~1 mile) to some 400kV power lines was quite depressing. Whenever the weather was damp, misty or raining (or all three simultaneously as this was in England), I basically could hear nothing on 160m on any sort of antenna. Attempts to null the noise were complete failures as there were multiple sources of corona. When the weather was dry everything was fine. The solution was to move about 15 miles from the closest EHV line and later to move 4000 miles over the ocean! 73 Roger VE3ZI/G3RBP ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Shunt fed tower
Hi Larry, For a tribander on a mast, just use one inch diameter conductor for the mast, the boom and the first and last 20 meter elements. For a 40 linear loaded 2 element, similarly model the mast, the boom and the non-driven element as if you unfolded and stretched out the linear loading. This will get you very close. Be sure to model the conductors on the tower including what happens to them when they get to the bottom, like run over the lawn to the house. 73, Guy. On Thu, Dec 15, 2011 at 4:14 PM, Larry lkn...@nc.rr.com wrote: I haven't done much modeling in the past.I have a KT36XA which would be very ugly if I had to model it precisely. I also have a linearly loaded 2 el 40M yagi. I suspect that the loading wires probably are negligible in the overall scheme of things at 160M. So I would guess that there some approximation that would give reasonable results as a place to start on the tower. Suggestions? 73, Larry W6NWS - Original Message - From: W2XJ w...@nyc.rr.com To: topband@contesting.com Sent: Thursday, December 15, 2011 10:34 AM Subject: Re: Topband: Shunt fed tower Vertical antennas have been shunt fed for over 70 years. There is no magic involved. Very few MW verticals are ever resonant and resonance is irrelevant. The only important thing is to match the TX so it is happy. The easiest way to deal with matching is to first model on EZNEC which will give an approximation of where the shunt should be connected and then physically moving the shunt to find the 50 ohm point which should be determined by measurement. Once that is accomplished, measure the J and calculate the necessary C to cancel it. On 12/15/11 10:17 AM, Joe Subich, W4TV wrote: On 12/15/2011 7:27 AM, W2RU - Bud Hippisley wrote: Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. That is true but a 100 foot tower with decent sized 20M monobander or 24 foot boom tribander with the front/back elements grounded and a short 40 meter yagi will most certainly have a natural resonant point below 1.8 MHz. Additional side mounted yagis will further lower the resonant point. A tower with resonant point below 1.8 MHz will have a higher impedance which will transform badly in a gamma with high element to rod ratio and narrow spacing. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way — I simply steady the top portion while making electrical connection to the tower at the tap point. R and L Electronics (www.randl.com) has insulators for cage dipoles. They are about 3.5 OD with 12 1/4 holes on a roughly 3 diameter and make excellent insulators for a fat gamma rod. One can use 3, 4, or 6 wires in the cage and achieve effective diameters between 2 and 3 inches. 73, ... Joe, W4TV On 12/15/2011 7:27 AM, W2RU - Bud Hippisley wrote: Many shunt-fed, loaded towers on 160 exhibit narrow bandwidth and are difficult to match with a single series capacitor for one simple reason: The gamma rod (shunt wire) is TOO CLOSE to the tower. A few years ago, after struggling with Omega matches in conjunction with MANY trips up my tower, I modeled my system with EZNEC. For me, the sweet spot was to position the gamma rod SEVEN (7) FEET from the tower! For my tower (92 feet of Rohn 45, 8 feet of mast above it, shorty 40 at 97 feet and 4-el. 20-m monobander at 92 feet), the tap point is 57 feet up. My minimum SWR (in a 50-ohm system) at my center frequency is around 1.4:1, but my 2.0:1 SWR bandwidth increased (with no change in my skimpy radial field) to over 75 kHz as a result of my modeling efforts. Having struggled with Omega matches for years before that, the present setup is a joy. One way to get in the ballpark without doing any serious modeling is to think about the gamma matches you've probably seen (and maybe even used) on your 20-meter beams. Very roughly, since 160 meters is 1/8 the frequency of 20 meters, all things being equal, the gamma rod spacing on 160 should be eight times what it is on 20. If your 20-meter gamma rod is 7 or 8 inches from your driven element, that's equivalent to 5 or 6 feet on 160. Of course, a grounded, shunt-fed, top-loaded tower isn't exactly the same as a full-size half-wavelength Yagi driven element, but the comparison is at least a good starting point. Construction: My local ACE hardware store stocks 8-foot lengths of angle aluminum, which is what I used for my horizontal tap rod. Their heaviest-duty stock is more than strong enough to support itself plus the top of my gamma rod. I don't support the weight of the entire rod -- which consists of stepped diameters of plumbing tubing -- that way — I simply steady the top portion while making
Topband: Balun Designs FCP Isolation Transformer Link
Direct link to Balun Designs FCP Isolation Transformer: http://www.balundesigns.com/servlet/the-108/1-cln-1-High-Isolation-Balun/Det ail ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: T-200 vs. T-300
#2 powdered iron at mu of 10 is the lowest mu of the powdered iron types listed with a frequency range that covers 160 meters (in some lists #2 is 2-30). You can rest assured Jerry Sevick had the list below. In his 160 meter comparison with #2 material, he tested 1,3,15 and 26. Number 6 really doesn't work under 10 MHz, as specified in other lists. It's a replaced mix that has had problems. Here's a composite list of powdered iron materials from various incomplete sources. 0 Mix (Tan) 100-300 MHz u=1 1 Mix (Blue) 0.5-5 Mhz u=20 *2 Mix* (Red) 1-30 MHz, high volume resist. u=10 [Alt list 2-30 Mhz] 3 Mix (Gray) .05-.5 MHz, u=35 *6 Mix* (Yellow) 1-50 MHz, similar to mix #2. u=8 [alt list 10-50 MHz, alt list use #8] 7 Mix 3-35 MHz, u=9 small cores only *8 Mix *(Yellow / Red) 1-50 MHz, replaces 6 mix. u=35 10 Mix 30-100 MHz, u=6 12 Mix 50-200 MHz, u=4 15 Mix 0.1-2 MHz, u=25 *17 Mix* (Blue/Yellow) 50-200 MHz, good Q. u=3 [alt list u=4] *18 Mix* (Green/Red) u=55, Low Core Loss, Similar to 8 Mix *26 Mix* (Yellow/White) DC-800 KHz, great 60 Hz. EMI range. Line 'em up on speakers / AC wires u=75 *40 Mix* (Green/Yellow) Power conversion similar to mix 26 *52 Mix* (Green/Blue) DC-1 MHz, high perm. u=75 73, Guy. On Thu, Dec 15, 2011 at 10:50 PM, ZR z...@jeremy.mv.com wrote: - Original Message - From: Guy Olinger K2AV olin...@bellsouth.net To: rich...@karlquist.com Cc: topband@contesting.com; Martin hamra...@vr-web.de Sent: Thursday, December 15, 2011 10:05 PM Subject: Re: Topband: T-200 vs. T-300 Hi Rick, No magic. Just the right stuff, for the FCP, anyway. To your particulars, when Jerry Sevick measured various ferrites, he measured the lowest loss at mu=40. This was very low, as was the #2 powdered iron at mu=10, the lowest of the powdered iron formulas. Since when is a 2 mix the lowest mu? It is ideal for QRO and HF since 6 and 7 mix arent made in QRO sizes and arent suitable at 160 anyway. Carl KM1H So use of ferrites introduces a significantly reduced number of turns, with a much more coarse granularity of possible inductive values, that has to be worked out to use with the FCP, AND the behavior of the mu=40 core under highly reactive loads is not spec'd by the manufacturer. The ferrite will have far less radiating surface if it does heat up under extreme reactive load, AND the length of the parallel bifilar wires may not be enough to cover 160 with the needed behavior in this app. But my admonition about no ferrites has more to do with my knowing that people have misc T240 and T200 form factor ferrites of ALL KINDS laying around, and want to use the one they just found down in the junk box, which does NOT have the material # or mu marked on it anywhere. And these requests seem to pop up just before a contest, when most hope of getting the correct stuff before contest has gone by the wayside. You will note that I have pounded in Amidon T300A-2 #2 powdered iron toroid or strict equivalent, over and over again. And I get back please, please, please tell me that I can use my junkbox ferrite toroid. But don't hold your breath. In over four years of working with non-resonant antenna solutions on 160, **NONE** of the ferrites we tried to use made it. We burnt or cracked ALL of them at QRO. ALL of them. Really. Ferrite demolition derby. I have a new collection of #31 ferrite stuff, but I use those in low band RFI suppression, not transformers. So I'm NOT going to tell anyone it's OK to use a ferrite toroid for feeding an FCP. Beyond that, what is NOT in doubt is that the #2 powdered iron choice works and works well. The installations where I have been able to run QRO brick on key and quick go check toroid temp have all been stone cold. Anyone has contrary experience please let us know ASAP. We will certainly want to investigate and determine why in one place and why not in another. As to why he made his #2 powdered iron choice, Jerry Sevick W2FMI, covers this convincingly in his book, pages 58-63, which I will NOT try to reproduce on the reflector, as even if I did, I can't pass along the essential graphs, photos and diagrams. (Understanding, Building, and Using Baluns and Ununs -- Theory and Practical Designs for the Experimenter, Jerry Sevick W2FMI, Copyright 2003, CQ Communications, Inc., Hicksville, New York) I have found, over the time that I have been working on top-band issues, that dropping back after blowing something up and consulting W2FMI or his material has been most valuable. Alas, Jerry is a silent key, and I can no longer phone him to further expound upon his choices. He particularly chose the large #2 powdered iron cores for applications with a lot of stress on the core, particularly 160 meters. Some key quotes: Because my simple loss measurements indicated that the higher permeability powdered-irons had more loss than the No. 2 material, I decided to design a 4:1
Topband: Feeding the Shunt Fed Tower
I have been using a shunt fed tower on 160 since 1979. My first was a 60 foot Universal with a TH6 on top. The shunt wire was three #14 wires twisted together and tied to a three foot aluminum tube very near the top of the tower. It was fed through a simple, single variable capacitor with a voltage rating of about 3000 volts. The second version was a 70 foot Universal with the TH6 and later a stack of three beams. With a taller tower the shunt tap came down to about 56 feet using the twisted wires. The third version is the current 80 foot Universal. The shunt feed was changed to 1/2 aluminum CATV hardline. This year I changed the bread slicer to a vacuum variable (approx 600 pf) and use an air variable as an Omega capacitor. My tap is now at the 48 foot level. My tower appears to have a natural resonance around 1765 khz. After years of turning on the rig and send 20 watts out to the gamma, and then running outside to tune for minimum SWR, I had a brain spasm this year and took the MFJ SWR analyzer out to the capacitor box and hooked it directly to the coax connector. Then I tuned the vacuum variable and omega cap for minimum reactance and SWR, 1 to 1. Works like a champ! 73, Dennis W0JX/8 Milan, OH ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
