|
Bird Brained Question
For the first time in many years, I'm about to put up a 20 meter monobander on
a tower. The XYL is asking questions I cannot answer, specifically relating to RF and birds. I wouldn't want to be a bird sitting on an element when a KW is supplied to it? Are my concerns valid? Gary K5QT |
"AA5QT" wrote For the first time in many years, I'm about to put up a 20 meter monobander on a tower. The XYL is asking questions I cannot answer, specifically relating to RF and birds. I wouldn't want to be a bird sitting on an element when a KW is supplied to it? Are my concerns valid? Gary K5QT Your concerns, no. The birds, yes. I push 1kw out of a 1/2 wave horizontal dipole and the birds never choose it as a resting place. Down near the ground, it hasn't impeded the population of several Finch, Cardinal, Northern Thrush and Robin families. Jack Virginia Beach, VA |
|
Gary,
Given the number of beam antennas around and how long they have been up, if it were really a valid consern, there should be huge flocks of dead birds littering the yards of the beam owners. The SPCA and the Audubon Society (sp) SWAT teams would be breaking down doors, etc. It wouldn't be pretty! 'Doc |
AA5QT wrote:
For the first time in many years, I'm about to put up a 20 meter monobander on a tower. The XYL is asking questions I cannot answer, specifically relating to RF and birds. I wouldn't want to be a bird sitting on an element when a KW is supplied to it? Are my concerns valid? I've tried to chase Starlings away by applying 100W to my 20m rotatable dipole. Some fly away. Some just sit there and tingle, jumping around and ruffling their feathers. On my antenna, the only place guaranteed to chase away a bird is the feedpoint with one foot on each side. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Maybe get a rent a hawk or the duty owl.
Seriously -- the Ham stores sell a good looking owl to put on towers -- don't if they scare away the other boids -- but they look good (;-) -- Lamont Cranston The Shadow Knows "Cecil Moore" wrote in message ... AA5QT wrote: For the first time in many years, I'm about to put up a 20 meter monobander on a tower. The XYL is asking questions I cannot answer, specifically relating to RF and birds. I wouldn't want to be a bird sitting on an element when a KW is supplied to it? Are my concerns valid? I've tried to chase Starlings away by applying 100W to my 20m rotatable dipole. Some fly away. Some just sit there and tingle, jumping around and ruffling their feathers. On my antenna, the only place guaranteed to chase away a bird is the feedpoint with one foot on each side. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Woudn't the bird consitute but a tiny capacitance to ground and thus not
experience an RF burn of consequence? "Cecil Moore" wrote in message ... AA5QT wrote: For the first time in many years, I'm about to put up a 20 meter monobander on a tower. The XYL is asking questions I cannot answer, specifically relating to RF and birds. I wouldn't want to be a bird sitting on an element when a KW is supplied to it? Are my concerns valid? I've tried to chase Starlings away by applying 100W to my 20m rotatable dipole. Some fly away. Some just sit there and tingle, jumping around and ruffling their feathers. On my antenna, the only place guaranteed to chase away a bird is the feedpoint with one foot on each side. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Chuck wrote in message ... Woudn't the bird consitute but a tiny capacitance to ground and thus not experience an RF burn of consequence? After all, birds sit on high voltage distribution lines with no ill effects. At some point, I guess, corona leakage becomes a factor. You don't see them sitting on the 100kv+ stuff. |
"WB2JKX" wrote in message ... Chuck wrote in message ... Woudn't the bird consitute but a tiny capacitance to ground and thus not experience an RF burn of consequence? Let's see here... First, The bird must have some fundamental capacitance to the rest of the known universe. lets take a stab and say it is 10pf since he is pretty far away from almost everything. I'm sure there is a formula for the capacitance of a 4 inch diameter sphere somewhere... Second, Lets model this as 10pf to ground. Now, what's the current through this 10pf at the tip of the antenna (assuming his foot-element contact resistance is well below the Xc)...We're at 20M, 15M or 10M, so, without resorting to math, Xc is pretty low, in general terms. Hmmm could be substantial even at 100W, no? Sounds like his poor feet could indeed get enough to make life difficult. After all, birds sit on high voltage distribution lines with no ill effects. At some point, I guess, corona leakage becomes a factor. You don't see them sitting on the 100kv+ stuff. Completely different situation due to the 60 HZ. The 10pf would lead to negligible current... "Just don't get one foot on each wire, Son. Your Unkle Tweety did that and there was a loud pop and he was gone in a bright flash. Some feathers and a bad smell was all that remained." "On the other hand, son, getting to the top of one of those really high man made trees with wires and your feathers'll all stand on end! Its really cool! Just don't let your mother catch you doing that." -- Steve N, K,9;d, c. i My email has no u's. |
Birds also sit on high-tension lines carrying many amps at thousands of
volts. Makes you wonder if it interferes with their built-in compass. "AA5QT" wrote in message ... For the first time in many years, I'm about to put up a 20 meter monobander on a tower. The XYL is asking questions I cannot answer, specifically relating to RF and birds. I wouldn't want to be a bird sitting on an element when a KW is supplied to it? Are my concerns valid? Gary K5QT --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.708 / Virus Database: 464 - Release Date: 6/18/2004 |
"WB2JKX" wrote in message ... Chuck wrote in message ... Woudn't the bird consitute but a tiny capacitance to ground and thus not experience an RF burn of consequence? After all, birds sit on high voltage distribution lines with no ill effects. At some point, I guess, corona leakage becomes a factor. You don't see them sitting on the 100kv+ stuff. A more valid comparision is how much of a wavelength does the bird's two feet shunt on the antenna wire? I'd suspect the problem would increase with frequency; becoming very painful in the VHF regions. Peter |
"Steve Nosko" wrote in message ... "WB2JKX" wrote in message ... Chuck wrote in message ... Woudn't the bird consitute but a tiny capacitance to ground and thus not experience an RF burn of consequence? Let's see here... First, The bird must have some fundamental capacitance to the rest of the known universe. lets take a stab and say it is 10pf since he is pretty far away from almost everything. I'm sure there is a formula for the capacitance of a 4 inch diameter sphere somewhere... Second, Lets model this as 10pf to ground. Now, what's the current through this 10pf at the tip of the antenna (assuming his foot-element contact resistance is well below the Xc)...We're at 20M, 15M or 10M, so, without resorting to math, Xc is pretty low, in general terms. Hmmm could be substantial even at 100W, no? Sounds like his poor feet could indeed get enough to make life difficult. After all, birds sit on high voltage distribution lines with no ill effects. At some point, I guess, corona leakage becomes a factor. You don't see them sitting on the 100kv+ stuff. Completely different situation due to the 60 HZ. The 10pf would lead to negligible current... "Just don't get one foot on each wire, Son. Your Unkle Tweety did that and there was a loud pop and he was gone in a bright flash. Some feathers and a bad smell was all that remained." "On the other hand, son, getting to the top of one of those really high man made trees with wires and your feathers'll all stand on end! Its really cool! Just don't let your mother catch you doing that." i havent noticed a problem with injured birds on the broadcast towers. FMs up to 100,000 W ERP. (about 14,000 W per bay in my case). 5,000 W AM towers both non and directional including top loaded arrays. not a problem either (in fact i have had birds nest in them) I have one site that uses open wire transmission lines to feed a 5 tower array... 10.4 amps of RF at the common point. up to 10 amps of base current. located in a wildlife refuge. still no birds frying themselves. now i have been burnt a few times working on this thing... maybe it goes to show that birds ARE smarter then radio engineers. |
Tim Perry wrote:
now i have been burnt a few times working on this thing... maybe it goes to show that birds ARE smarter then radio engineers. Birds are smart enough not to stand on the ground and put their wings on the hot wires. :-) -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
-- Lamont Cranston The Shadow Knows "Cecil Moore" wrote in message ... Tim Perry wrote: now i have been burnt a few times working on this thing... maybe it goes to show that birds ARE smarter then radio engineers. Birds are smart enough not to stand on the ground and put their wings on the hot wires. :-) And the ones that don't go into the Field Day Bird Stew pot. Field day -- participate -- you may need the experience when the BIG one hits. Grumppp no power, no phones, no cell phones, no internet |
AA5QT wrote:
For the first time in many years, I'm about to put up a 20 meter monobander on a tower. The XYL is asking questions I cannot answer, specifically relating to RF and birds. I wouldn't want to be a bird sitting on an element when a KW is supplied to it? Are my concerns valid? Gary K5QT Back in the '60's, at Naval Radio Station CKN, we had a number, perhaps ten or fifteen, of multikilowatt transmitters all feeding the antennas through open wire line. The transmitter building was like a huge barn with all the wires running from the transmitters to the antennas. An occasional bird would fly in, and we would chase them out with a broom! We never lost a bird, but the junior hand on the watch would have to sweep out, and in an evening we could count on half a trash-can full of dead flies! The building was in the middle of a swamp area and full of assorted flying insects. Those same flies were responsible for occasional trip-off's of the transmitters, and you could hear frequent snaps if and when they happened into a critical area, for example between capacitor plates, and drew an arc. If you picked up a fluorescent tube, it would light up from all the RF floating around. I've often wondered about how much effect the RF had on me -- although my Ex would tell you I am stark raving mad! :-0 The antenna fields should have been filled with dead birds if the feeders or the antennas themselves were a hazard, but apparently not. Ah, the memories! Great! Irv VE6BP -- -------------------------------------- Diagnosed Type II Diabetes March 5 2001 Beating it with diet and exercise! 297/215/210 (to be revised lower) 58"/43"(!)/44" (already lower too!) -------------------------------------- Visit my HomePage at http://members.shaw.ca/finkirv/ Visit my Baby Sofia website at http://members.shaw.ca/finkirv4/ Visit my OLDTIMERS website at http://members.shaw.ca/finkirv5/ -------------------- Irv Finkleman, Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP Calgary, Alberta, Canada |
On Thu, 24 Jun 2004 14:17:23 GMT, Irv Finkleman
wrote: Back in the '60's, at Naval Radio Station CKN, we had a number, perhaps ten or fifteen, of multikilowatt transmitters all feeding the antennas through open wire line. [snip] I've often wondered about how much effect the RF had on me -- although my Ex would tell you I am stark raving mad! :-0 Irv VE6BP About the same time I was stationed at a loran station and while serving there I "hot jumped" the tower several times. Loran stations put out a maga-watt and I never noticed any sensation - not even a slightest tingle. But, on a damp day, jumping off the tower would draw a heck of an arc with a resounding ZAAAAAP. However, like you Irv, my wife would be unable to afirm my healty mental state. G Danny, K6MHE |
"Da Shadow" wrote in message news:T6BCc.7593$rn1.2467@okepread07... -- Lamont Cranston The Shadow Knows "Cecil Moore" wrote in message ... Tim Perry wrote: now i have been burnt a few times working on this thing... maybe it goes to show that birds ARE smarter then radio engineers. Birds are smart enough not to stand on the ground and put their wings on the hot wires. :-) actually in this case grounded or ungrounded makes no difference. the RF just burns a very painful hole in what ever part of your skin you carelessly brush against the hot wires. some of the vacuum variable caps have adjustment knobs with metal set screws... ouch try to remember to only adjust with your fingertips touching the bakelite. this is a very old array built in 1949. And the ones that don't go into the Field Day Bird Stew pot. Field day -- participate -- you may need the experience when the BIG one hits. Grumppp no power, no phones, no cell phones, no internet |
The only time I've heard of birds coming out on the short end of the
deal was at a VOA transmitter site in Ohio running megawatts of power along open feed lines. I'm sure your maximum forward power wouldn't even approach their reflected power (grin). Mark -- On 23 Jun 2004 12:17:49 GMT, (AA5QT) wrote: For the first time in many years, I'm about to put up a 20 meter monobander on a tower. The XYL is asking questions I cannot answer, specifically relating to RF and birds. I wouldn't want to be a bird sitting on an element when a KW is supplied to it? Are my concerns valid? Gary K5QT Mark |
Came home one day in the early fall several years ago and found that many
black birds were sitting on all elements of my top 18E log periodic. Decided to see what happened so I fired up the linear on 17 M and let out a full carrier. Looked like at least 1/2 the elements had significant voltage on them and the birds that didn't fall directly down and landed on the ground, flew off...for a while, some crashed also...empirical testing of voltage (power?) distribution....interesting....(:) Chuck...K1KW "AA5QT" wrote in message ... For the first time in many years, I'm about to put up a 20 meter monobander on a tower. The XYL is asking questions I cannot answer, specifically relating to RF and birds. I wouldn't want to be a bird sitting on an element when a KW is supplied to it? Are my concerns valid? Gary K5QT |
Cecil Moore wrote in message ...
AA5QT wrote: For the first time in many years, I'm about to put up a 20 meter monobander on a tower. The XYL is asking questions I cannot answer, specifically relating to RF and birds. I wouldn't want to be a bird sitting on an element when a KW is supplied to it? Are my concerns valid? I've tried to chase Starlings away by applying 100W to my 20m rotatable dipole. Some fly away. Some just sit there and tingle, jumping around and ruffling their feathers. On my antenna, the only place guaranteed to chase away a bird is the feedpoint with one foot on each side. Cecil, place a bird feeder on the boom directly in front of the feedpoint. ;^) |
Cecil Moore wrote in message ...
AA5QT wrote: For the first time in many years, I'm about to put up a 20 meter monobander on a tower. The XYL is asking questions I cannot answer, specifically relating to RF and birds. I wouldn't want to be a bird sitting on an element when a KW is supplied to it? Are my concerns valid? I've tried to chase Starlings away by applying 100W to my 20m rotatable dipole. Some fly away. Some just sit there and tingle, jumping around and ruffling their feathers. On my antenna, the only place guaranteed to chase away a bird is the feedpoint with one foot on each side. Cecil, place a bird feeder on the boom directly in front of the feedpoint. ;^) |
| All times are GMT +1. The time now is 09:52 PM. |
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com