Topband: EZnec - 4nec2 - MODELING THE 1/4 SLOPERS.
Good morning! Has anyone modeled the 1/4 slopers? Perhaps the Alpha Delta DXA? 73 -- Juan A. Granados /K4LCD - WF2XXQ https://sites.google.com/site/k4lcdars/ https://sites.google.com/site/thesdrinstitute/ https://groups.yahoo.com/neo/groups/sdr-users/info Skype: juangranados-miami _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: EZnec - 4nec2 - MODELING THE 1/4 SLOPERS.
Has anyone modeled the 1/4 slopers? Perhaps the Alpha Delta DXA? The pattern and performance of a 1/4 wave sloper is extremely dependent on the tower and what is on the tower, the guy lines (if uninsulated), and even how the tower is grounded. There are very common cases where it won't work at all, cases where it works fairly well, and everything between the two extremes. _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Results OA4TT 3/8/2014
Hi Topbanders, We made 43 QSO's this morning EU-27 US-15 SA-1 To me conditions were not great. I had lots of problems receiving. Stations seemed to be hearing me much better than I was hearing them. This is still our summer and there appeared to be some storm activity over the Andes. I had to really dig on most stations to get the callsigns and as a result rate was low. Sorry to those I could not pull out. If there is interest we can try again in a month or so. QSO's will be on lotw in a few days. 73 Jack _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: EZnec - 4nec2 - MODELING THE 1/4 SLOPERS.
IMHO a wire 1/4 wave length long wire should preferably be electrically connected to the tower and fed from the bottom of the slope against a good ground system. AM stations that have done this in emergencies report good results.In fact some consulting engineers were so impressed after making F/S measurements they have tried to get this method approved as a simple way to take advantage of the directional qualities in the direction of the slope instead of the expense of a two tower array and phasers. These stations needed only a few db's of cancellation of the rear side of the tower. Of course the FCC said not because this method was too unorthodox for them to deal with. But the concept does work with a slight bump in favor of the slope direction. This is merely a way of shunt feeding a grounded tower that can allow for the slant to be brought close to the ham shack where an ATU or matching network can be placed. Herb, KV4FZ On 3/8/2014 10:41 AM, Tom W8JI wrote: Has anyone modeled the 1/4 slopers? Perhaps the Alpha Delta DXA? The pattern and performance of a 1/4 wave sloper is extremely dependent on the tower and what is on the tower, the guy lines (if uninsulated), and even how the tower is grounded. There are very common cases where it won't work at all, cases where it works fairly well, and everything between the two extremes. _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Results OA4TT 3/8/2014
Hello Jack! Thanks for being QRV on 160m! Yes! Very much interest. Please activate your station on 160m again as soon as you can. 73 Lloyd - N9LB -Original Message- From: Topband [mailto:topband-boun...@contesting.com]On Behalf Of Jack Henry, OA4TT Sent: Saturday, March 08, 2014 10:52 AM To: topband@contesting.com Subject: Topband: Results OA4TT 3/8/2014 Hi Topbanders, We made 43 QSO's this morning EU-27 US-15 SA-1 To me conditions were not great. I had lots of problems receiving. Stations seemed to be hearing me much better than I was hearing them. This is still our summer and there appeared to be some storm activity over the Andes. I had to really dig on most stations to get the callsigns and as a result rate was low. Sorry to those I could not pull out. If there is interest we can try again in a month or so. QSO's will be on lotw in a few days. 73 Jack _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: EZnec - 4nec2 - MODELING THE 1/4 SLOPERS.
On 3/8/2014 9:08 AM, Herb Schoenbohm wrote: IMHO a wire 1/4 wave length long wire should preferably be electrically connected to the tower and fed from the bottom of the slope against a good ground system. Herb, That depends on the height of the tower. I have two sloping wires on opposite sides of my 110 ft tower (with SteppIR and 2M long Yagi on top) that are INSULATED from the tower and each fed from the bottom against four radials elevated about 20 ft. The tower is grounded and has a dozen or so quarter wave radials. The wires are held 5 ft away from the tower at the top by a 10 ft section of 4-in PVC conduit. One faces to 70 degrees, the other to 270 degrees. NEC predicts the same gain of 2-3 dB with F/B of about 6 dB, and that's about the way they hear. I feed one or the other, with a stub in the shack that opens the feed of the antenna not being driven. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: OA4TT activity night 8 Mar 04-06Z
On 3/6/2014 6:58 AM, Jack Henry, OA4TT wrote: My station is modest with a TL922 running 1 kW into a 42 ft vertical T loaded with abt 40 radials in a rural area. It's a good enough station that we were able to work back in 2008. Thanks very much for that. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: EZnec - 4nec2 - MODELING THE 1/4 SLOPERS.
Jim.You hit on a good point with a 1/4 sloper that it should be some distance, in your case 5 feet, from the tower at the top or high voltage end. Having the top right at the tower seems to deteriorate the performance overall as many who have tried this seem to underscore. What you have presumably are two verticals with an a periodic reflector which is your tower. Having switchable gain both on RX and TX and some F/B is great. I am glad you confirmed this with both NEC and on the air tests. Regards, Herb Schoenbohm, KV4FZ On 3/8/2014 2:38 PM, Jim Brown wrote: On 3/8/2014 9:08 AM, Herb Schoenbohm wrote: IMHO a wire 1/4 wave length long wire should preferably be electrically connected to the tower and fed from the bottom of the slope against a good ground system. Herb, That depends on the height of the tower. I have two sloping wires on opposite sides of my 110 ft tower (with SteppIR and 2M long Yagi on top) that are INSULATED from the tower and each fed from the bottom against four radials elevated about 20 ft. The tower is grounded and has a dozen or so quarter wave radials. The wires are held 5 ft away from the tower at the top by a 10 ft section of 4-in PVC conduit. One faces to 70 degrees, the other to 270 degrees. NEC predicts the same gain of 2-3 dB with F/B of about 6 dB, and that's about the way they hear. I feed one or the other, with a stub in the shack that opens the feed of the antenna not being driven. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: EZnec - 4nec2 - MODELING THE 1/4 SLOPERS.
Jim.You hit on a good point with a 1/4 sloper that it should be some distance, in your case 5 feet, from the tower at the top or high voltage end. Having the top right at the tower seems to deteriorate the performance overall as many who have tried this seem to underscore. What you have presumably are two verticals with an a periodic reflector which is your tower. Having switchable gain both on RX and TX and some F/B is great. I am glad you confirmed this with both NEC and on the air tests. While Jim's system is better, most people want to feed these things against the tower. With the shield attached to the tower, the tower is the ground. This is where all the problems with operating inconsistency come in. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
