Re: Topband: T vert feed
'Twas stated: Feedline coax shield 1.7 ohms. The single 1.7 ohms lowers the voltage and even in this case of what appears to be an excellent ground radials system, the coax will carry HALF the counterpoise current and waste most of that power, besides being a link...(etc.) Whaaat??? Where did that 1.7 ohm figure come fromspace? The size (gauge) of radial wires has very little effect on their effectiveness as radials, according everything I've ever read. Also, effective resistance to ground, due to such intimate coupling to earth when radials are at the surface or buried, evens out their equivalent resistances and reactances, rendering them un-tuned. Not comparable to elevated radials at all. Voltage and current nodes on surface or buried radials are smoothed and averaged out rendering them un-problematic. If no balun, including a choke-type, is used at the feedpoint of a vertical then the coax braid simply counts as another radial, averaged in with the many. Ferrites at the shack end can attenuate any residual RF on the braid if it is troublesome there (unlikely). 73, Roy K6XKIowa ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: T vert feed
Would not each one remain 100 ohms? If the analysis is correct, they are in parallel and that does not add linearly based on the individual wire values as would a series connection. 73/jeff/ac0c www.ac0c.com alpha-charlie-zero-charlie -Original Message- From: Charles Moizeau Sent: Monday, January 30, 2012 12:37 PM To: royan...@ncn.net ; Topband Subject: Re: Topband: T vert feed Nope. With 100 Ohms per radial and 60 of them all the same and in parallel with each other, one gets 1.6 Ohms; close enough. 73, Charles, W2SH From: royan...@ncn.net To: topband@contesting.com Date: Mon, 30 Jan 2012 12:15:10 -0600 Subject: Re: Topband: T vert feed 'Twas stated: Feedline coax shield 1.7 ohms. The single 1.7 ohms lowers the voltage and even in this case of what appears to be an excellent ground radials system, the coax will carry HALF the counterpoise current and waste most of that power, besides being a link...(etc.) Whaaat??? Where did that 1.7 ohm figure come fromspace? The size (gauge) of radial wires has very little effect on their effectiveness as radials, according everything I've ever read. Also, effective resistance to ground, due to such intimate coupling to earth when radials are at the surface or buried, evens out their equivalent resistances and reactances, rendering them un-tuned. Not comparable to elevated radials at all. Voltage and current nodes on surface or buried radials are smoothed and averaged out rendering them un-problematic. If no balun, including a choke-type, is used at the feedpoint of a vertical then the coax braid simply counts as another radial, averaged in with the many. Ferrites at the shack end can attenuate any residual RF on the braid if it is troublesome there (unlikely). 73, Roy K6XKIowa ___ 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 vert feed
Oh, yeah. It will. If you are unlucky and it is presenting a current node at the antenna connection. All the MORE likely if you have a really good ground at the house entry point. Get used to it. Each little wire running off from the center is a **DRIVEN** element in the system, and if the coax shield is not blocked, the coax shield is an element DRIVEN with power from the base of the antenna. It can be that low, it's insulated, it has a very large surface, and because there are miscellaneous distributed and specific terminations at the other end, you CAN very definitely have current nodes if it's driven with power at the antenna end. That is where you can get VERY low effective series resistances. Maybe you particularly will, maybe you won't, with your SPECIFIC piece of coax and routing, grounding, yada, yada. But the warning of the 50/50 possibility has to remain. I'm really quite sure some of you out there ARE lucky in this very miscellaneous regard. Carry on. Enjoy life. Kiss a pretty woman. Work rare DX. As for the REST of you. The trick is to remember that without a block you are driving that shield with counterpoise power, the same as each one of the radials individually. 73, Guy. On Mon, Jan 30, 2012 at 1:53 PM, Roy royan...@ncn.net wrote: This is the part I'm objecting to: the coax will carry HALF the counterpoise current and waste most of that power, besides being a link...(etc.) No, no, nertz. Where did that notion originate? Roy K6XK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: pace...@aol.com Subject: understanding 160 meter propagation
It sounds like classic spotlight propagation, Larry. Happens a lot on 160. I feel lucky to have experienced it several times over the last 58 years on topband. The most memorable one for me occurred about 8 years ago on a Saturday evening. I called CQDX about sunset and didn't expect much because the usual early spots by East Coasters were not showing up on the Summit. Several Russian and eastern European stations answered me. Reports were 579 to 599 both ways. It continued until sunrise in the British Isles as I worked my way across the continent. By that time reports were more like 449 to 569. I worked about 100 stations. I hardly heard any stations east of the Mississippi work any EU that night. On Sunday morning I had an eMail from John, ON4UN asking me what I was running last night because the only strong stations he was hearing was me and K9DX. Well, for me it was a spotlight propagation burst... for John, K9DX it was that fantastic layout he had. I was running an OMNI 6+ and a TenTec Hercules solid state amp at 500 watts into a 520' horizontal loop at 50'. Boy, was that fun! 73, Barry ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Fw: T vert feed
- Original Message - From: Brian Mattson k8...@hughes.net To: Guy Olinger K2AV olin...@bellsouth.net Sent: Monday, January 30, 2012 9:22 PM Subject: Re: Topband: T vert feed Let me see if I have this right. With an unfortunate length of coax (half wave or multiple thereof), the house ground rod appears as a 1.7 ohm impedance at the base of the antenna feed. Why not avoid the tuned coax complication and put a ground rod right at the vertical feed point. With a 1/4 wave vertical at 36 ohms and a 1.7 ohm ground rod, efficiency is better than 95%! I'm impressedand who said a ground rod isn't much good for verticals? Just think, you can pull up all those radials sell them for scrap copper... Brian K8BHZ - Original Message - From: Guy Olinger K2AV olin...@bellsouth.net To: Roy royan...@ncn.net Cc: topband@contesting.com Sent: Monday, January 30, 2012 5:32 PM Subject: Re: Topband: T vert feed Oh, yeah. It will. If you are unlucky and it is presenting a current node at the antenna connection. All the MORE likely if you have a really good ground at the house entry point. Get used to it. Each little wire running off from the center is a **DRIVEN** element in the system, and if the coax shield is not blocked, the coax shield is an element DRIVEN with power from the base of the antenna. It can be that low, it's insulated, it has a very large surface, and because there are miscellaneous distributed and specific terminations at the other end, you CAN very definitely have current nodes if it's driven with power at the antenna end. That is where you can get VERY low effective series resistances. Maybe you particularly will, maybe you won't, with your SPECIFIC piece of coax and routing, grounding, yada, yada. But the warning of the 50/50 possibility has to remain. I'm really quite sure some of you out there ARE lucky in this very miscellaneous regard. Carry on. Enjoy life. Kiss a pretty woman. Work rare DX. As for the REST of you. The trick is to remember that without a block you are driving that shield with counterpoise power, the same as each one of the radials individually. 73, Guy. On Mon, Jan 30, 2012 at 1:53 PM, Roy royan...@ncn.net wrote: This is the part I'm objecting to: the coax will carry HALF the counterpoise current and waste most of that power, besides being a link...(etc.) No, no, nertz. Where did that notion originate? Roy K6XK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
