Topband: Prop For ARRL 160
It was totally stinko for the contest. 73, Jim K9YC _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Ground conductivity discussions … oops
> Hi Jim … thanks for the info. Rudy’s latest method is the one I was > planning to employ. Brian, K6STI also mentioned Rudy’s method. Good > consensus on which method to use! > > Yes, all other elements were either de tuned or on the ground. I have > checked each vertical one at a time (with others decoupled) and read 25 > ohms on all 4 elements. Such a head scratcher! I’m beginning to the my > aluminum elements are doped with Nichrome! :-) > > Dennis, K7FL > > > On Mon, Dec 5, 2022 at 9:33 AM James V Redding PE > wrote: > >> Here is a link to a method of actually measuring the soil complex >> conductivity characteristics and it is focused on 80M: >> >> https://rudys.typepad.com/files/soil-characteristics-qex.pdf >> >> Since the depth of the measurement is a function of frequency, the >> numbers for 80M may be quite different than for other HF bands. >> >> Was also curious whether the elements were detuned for their individual >> impedance measurements like would be done with a BCB array or if the 25 >> ohms is a common point measurement. >> >> Jim/VEZ >> >> >> >> On Sun, Dec 4, 2022 at 9:21 AM Dennis Ashworth >> wrote: >> >>> I meant to post this to the TowerTalk group. It still may be relevant to >>> Topband ops. >>> >>> Dennis, K7FL >>> >>> -- Forwarded message - >>> From: Dennis Ashworth >>> Date: Sat, Dec 3, 2022 at 8:54 AM >>> Subject: Ground conductivity discussions >>> To: >>> >>> >>> Very interesting and timely discussions on radials and ground >>> conductivity. >>> I’m currently rebuilding an 80M broadside array (with shortened, top >>> loaded >>> elements) in SW Utah that I’ve modeled at 12 ohms impedance. The current >>> antenna was tested and the impedance measured was 25 ohms. Each element >>> in >>> the array (4 total) also measured 25 ohms. What accounts for additional >>> system loss? >>> >>> Upon consulting the original builders, I learned they had also predicted >>> an >>> impedance of approximately 12 ohms. I’m not clear what methods or models >>> they used for their prediction. There are 4:1 baluns at the base of each >>> vertical which begs the question whether the array impedances were ever >>> checked post-install. I suspect not … and I doubt anything has changed >>> over >>> the years that would equally affect the impedance *on all 4 verticals.* >>> >>> Where I don’t blindly trust models (antennas or otherwise), I do believe >>> the 12 ohm figure is reasonable given the short, top loaded elements. I >>> reviewed the FCC conductivity tables for the locale and they indicate >>> 15-30 >>> millimos/meter. That’s pretty good! I would think the loss from a ground >>> system of 32, 1/4 wave plus radials would NOT account for the 12 ohms of >>> loss ground losses. But what if my ground conductivity is less than the >>> FCC >>> tables report? >>> >>> I’m going to the site again next week to install 26 additional 1/4 wave >>> radials on one of the verticals and see if (and how much) the measured >>> impedance drops. I’ll share my results here. >>> >>> This loss has to be a ground system issue. If so, adding radials and >>> seeing >>> a corresponding drop in impedance should confirm my suspicions. >>> >>> At some point, I’ll measure the ground conductivity, but it needs to wait >>> for warmer temps (current temp at site is 19F!). >>> >>> Insight from the masses always appreciated. >>> >>> >>> Dennis, K7FL >>> Las Vegas, NV >>> _ >>> Searchable Archives: http://www.contesting.com/_topband - Topband >>> Reflector >>> >> _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: My new 9 Circle works great!
Any links to this system? Joe WB9SBD On 12/4/2022 1:34 PM, Jim Miller wrote: Thanks to Steve's, VE6WZ, excellent YouTube videos, I decided to tackle a better RX antenna. I've been using a 2 element array phased by an NCC-2 which is better than what I've had in the past (BOG, K9AY) but I wanted better. After evaluating my space available and finding it too small I asked my neighbor for seasonal use of their adjoining lot and they graciously agreed! My N, NW and W elements are on their property. Steve's videos include KiCad files for the combiner and preamps and he was very helpful by email with any of my questions. I just completed the array last night and got it on the air and I was astonished by how well it worked. Of course it isn't going to create signals out of thin air but it is much quieter due to better RDF and the front to back is very impressive. Strong signals on the waterfall just disappear when the antenna is reversed! I'm very happy to get such an improved antenna for 80 and 160 in a 120ft diameter circle! As a bonus I use it with PSTRotator and a USB controlled relay box so no manual switch box is required on my desk. Just a mouse click selects the desired direction or it can track my logger automatically. FYI, most of the cost is in the aluminum, the combiner and preamps were pretty cheap to build. Many thanks to VE6WZ!! 73 jim ab3cv _ Searchable Archives:http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Fwd: Ground conductivity discussions … oops
Here is a link to a method of actually measuring the soil complex conductivity characteristics and it is focused on 80M: https://rudys.typepad.com/files/soil-characteristics-qex.pdf Since the depth of the measurement is a function of frequency, the numbers for 80M may be quite different than for other HF bands. Was also curious whether the elements were detuned for their individual impedance measurements like would be done with a BCB array or if the 25 ohms is a common point measurement. Jim/VEZ On Sun, Dec 4, 2022 at 9:21 AM Dennis Ashworth wrote: > I meant to post this to the TowerTalk group. It still may be relevant to > Topband ops. > > Dennis, K7FL > > -- Forwarded message - > From: Dennis Ashworth > Date: Sat, Dec 3, 2022 at 8:54 AM > Subject: Ground conductivity discussions > To: > > > Very interesting and timely discussions on radials and ground conductivity. > I’m currently rebuilding an 80M broadside array (with shortened, top loaded > elements) in SW Utah that I’ve modeled at 12 ohms impedance. The current > antenna was tested and the impedance measured was 25 ohms. Each element in > the array (4 total) also measured 25 ohms. What accounts for additional > system loss? > > Upon consulting the original builders, I learned they had also predicted an > impedance of approximately 12 ohms. I’m not clear what methods or models > they used for their prediction. There are 4:1 baluns at the base of each > vertical which begs the question whether the array impedances were ever > checked post-install. I suspect not … and I doubt anything has changed over > the years that would equally affect the impedance *on all 4 verticals.* > > Where I don’t blindly trust models (antennas or otherwise), I do believe > the 12 ohm figure is reasonable given the short, top loaded elements. I > reviewed the FCC conductivity tables for the locale and they indicate 15-30 > millimos/meter. That’s pretty good! I would think the loss from a ground > system of 32, 1/4 wave plus radials would NOT account for the 12 ohms of > loss ground losses. But what if my ground conductivity is less than the FCC > tables report? > > I’m going to the site again next week to install 26 additional 1/4 wave > radials on one of the verticals and see if (and how much) the measured > impedance drops. I’ll share my results here. > > This loss has to be a ground system issue. If so, adding radials and seeing > a corresponding drop in impedance should confirm my suspicions. > > At some point, I’ll measure the ground conductivity, but it needs to wait > for warmer temps (current temp at site is 19F!). > > Insight from the masses always appreciated. > > > Dennis, K7FL > Las Vegas, NV > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: ARRL 160
Re Packet and the contest May not be of interest to everyone. Sat evening around 0010 or so, had been running with a nice rate. Then a dupe. And another. And yet another. This continued for around 15 minutes until I finally QSY'd to escape. My guess of what happened: someone spotted me but with an incorrect call. On all those using packet, a new call popped up. They clicked on it, dumped in their call. Typically I work all dupes and, for the first few did but, as the volume grew, I replied with their call, mine and "B4". Most went away but a few insisted on a Q. In addition to showing how far our hobby has sunk, isn't it the responsibility of the calling station to actually copy the call sign? Many of the stations that duped me were very recognizable stations. Again, guessing, they were running SO2R, clicked on the spot, called and expected a quick Q. NEVER bothering to check accuracy of packet spot. Is it a valid contact if you don't copy the actual call sign? Even if the call was correct on packet. Or are we moving towards letting the computer do most of the work? Sure would be interesting if more contests were like the Stew Perry where no spotting assistance is allowed. You have to actually copy the information.. Yes, I know. A radical idea. Ron N4XD Sent using https://www.zoho.com/mail/ _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: DX Propagation for ARRL 160m Contest at W3HKK not so good
Had a check up last week and the doc recommended a flu shot. So I got one. Then on the day before the 160 contest, sure enough, I got the flu! Lacked the energy to participate in Day 1, but heard that not much Euro dx was coming through. Sat night I was feeling better so I got on for 7 hours. Saw a couple of Euro spots but heard nothing. Only dx worked were four stations in the Carrib. plus Hawaii. Saw KL7 spotted but did not copy. Finished with 252 Q's and a presunrise one hour run of 92 Q's/hr.* Not a lot worked in 6-7 land. Band was quiet with lots of quiet spots on night 2. * Once again I failed to get the radials uncoiled so they remained hanging in the walnut tree, while the 52' tall 130 ft INV-L antenna worked against just one 8 ft ground rod. Not too bad. Bob - _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: My new 9 Circle works great!
Thanks to Steve's, VE6WZ, excellent YouTube videos, I decided to tackle a better RX antenna. I've been using a 2 element array phased by an NCC-2 which is better than what I've had in the past (BOG, K9AY) but I wanted better. After evaluating my space available and finding it too small I asked my neighbor for seasonal use of their adjoining lot and they graciously agreed! My N, NW and W elements are on their property. Steve's videos include KiCad files for the combiner and preamps and he was very helpful by email with any of my questions. I just completed the array last night and got it on the air and I was astonished by how well it worked. Of course it isn't going to create signals out of thin air but it is much quieter due to better RDF and the front to back is very impressive. Strong signals on the waterfall just disappear when the antenna is reversed! I'm very happy to get such an improved antenna for 80 and 160 in a 120ft diameter circle! As a bonus I use it with PSTRotator and a USB controlled relay box so no manual switch box is required on my desk. Just a mouse click selects the desired direction or it can track my logger automatically. FYI, most of the cost is in the aluminum, the combiner and preamps were pretty cheap to build. Many thanks to VE6WZ!! 73 jim ab3cv _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Ground conductivity discussions
Grant, that higher Rr is the path I took as well. My 160m antenna is a bit longer than 1/4wl - trimmed in length so that the resistivity component of Z was 50 ohms. It's got Xl of course, so I use a series C bread slicer at the tower base to to cancel the Xl. My thought back then was that whatever the ground loss was, it would be about 1/3 less if the native feedpoint R was 50 ohms instead of something more close to a true 1/4 WL of around 35 ohms. 73/jeff/ac0c alpha-charlie-zero-charlie www.ac0c.com On 12/4/2022 11:19 AM, Grant Saviers wrote: Sounds like a great project. Isn't the reality that conductors (radials) in or near lossy mediums (earth, even salt water) have loss? And that the near field extends beyond the 1/4wl of the radials? The coupling among elements might be the reason 4:1 matching was used. So while more & longer radials reduce the loss, there is a limit. Note that my prior post for my antenna shows the feedpoint Z equals the Rr value of about 14 ohms only when the radials are elevated 100ft. Often called a ground plane antenna. I played a bit in Eznec with my antenna and a lot (128) more radials a few inches above your ground and saw essentially no change in Rg. Your higher conductivity ground will improve the pattern - more gain at lower angles. So I suspect adding 26 more radials to the existing 32 1/4wl will not make much improvement in Rg. I think Severns and Christman show this in their papers. Other solutions to lower ground loss is higher Rr of the antenna to improve the ratio Rr/Rg. eg 1/4wl tall verticals. The center fed 720ft BCB antennas eg KDKA are another solution. ie vertical dipoles. Grant KZ1W On 12/3/2022 08:54, Dennis Ashworth wrote: Very interesting and timely discussions on radials and ground conductivity. I’m currently rebuilding an 80M broadside array (with shortened, top loaded elements) in SW Utah that I’ve modeled at 12 ohms impedance. The current antenna was tested and the impedance measured was 25 ohms. Each element in the array (4 total) also measured 25 ohms. What accounts for additional system loss? Upon consulting the original builders, I learned they had also predicted an impedance of approximately 12 ohms. I’m not clear what methods or models they used for their prediction. There are 4:1 baluns at the base of each vertical which begs the question whether the array impedances were ever checked post-install. I suspect not … and I doubt anything has changed over the years that would equally affect the impedance *on all 4 verticals.* Where I don’t blindly trust models (antennas or otherwise), I do believe the 12 ohm figure is reasonable given the short, top loaded elements. I reviewed the FCC conductivity tables for the locale and they indicate 15-30 millimos/meter. That’s pretty good! I would think the loss from a ground system of 32, 1/4 wave plus radials would NOT account for the 12 ohms of loss ground losses. But what if my ground conductivity is less than the FCC tables report? I’m going to the site again next week to install 26 additional 1/4 wave radials on one of the verticals and see if (and how much) the measured impedance drops. I’ll share my results here. This loss has to be a ground system issue. If so, adding radials and seeing a corresponding drop in impedance should confirm my suspicions. At some point, I’ll measure the ground conductivity, but it needs to wait for warmer temps (current temp at site is 19F!). Insight from the masses always appreciated. Dennis, K7FL Las Vegas, NV _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
