Saw the comments on adding radials, so I had to comment on my situation this year.
I didnt get around to rolling out the 27 radials ( 30'-130' long depending on PL) yet, so I entered the ARRL 160 Contest with just my trusty single ground rod near the base of a walnut tree. (During lawn mowing season, I coil up my radials and hang them from the lower limbs of a 40 ft tall walnut tree near the NE corner of a 3 acre yard, all of which needs mowing. ). This year, due to a family conflict on Sun (today) I had to limit my operating to Day One Station: IC-7610 -ACOM 1000+ N1MM Logger + SAL-30 rx antenna. Conditions were quite good with even a fair bit of EU DX to be had. My N1MM+ log shows 539 QSOS's and 88 mults on Day One. Things were so good that among my first hour I had DE and ND in the log. Being an OG ( old goat) a few days away from my 80th birthday, I definitely need more periodic breaks, naps from the operating position. Those amounting to 4.5 hours out of the first 13.5 hours, before I pulled the plug at 3:30am after the rate slowed way down, as did my adrenalin level. I napped for two hours, then put in another 90 minutes prior to SR. That was it for me. Never could muster the energy needed for a second night. But the 160 contest is good for roaring starts, and this year was no exception with 131 Q's during the first two hours. As is my wont, I find a quiet spot usually between 1800-1810khz and CQ away. It never ceases to amaze, that you can CQ three times in a row with no takers, but on the 4th you get 3-4-5 replies. :). While the entire contest had good solid sigs and plenty of them, I found a 2nd peak around midnight-2 am where things really caught fire, for some reason. I may forever wonder "What IF" had I mustered the energy for my usual Day Two, but at least I had a good time of it while I lasted. And all that with no radials and a single ground rod, on a plot of land that was former Ohio farm land. SWR was 1.0:1 at 1830, and remained below 2:1 up to 1890 khz. Now when I DO uncoil my radials, it definitely shifts resonance and raises SWR. So my soda bottle shunt inductor gets played like an accordion to bring it back down. Plus, this year my usual UNUN was also out of the circuit. Despite all of the above, I really didnt see any significant difference in performance. So I have to agree, that a couple of extra radials here and there would be impossible to detect at the other end. PS My own rule of thumb on radials is to keep adding them until I see no further change in SWR - which increases as I add radials - compared to a naked ground rod. -----------------------------------------From: topband-requ...@contesting.com To: topband@contesting.com Cc: Sent: Saturday December 4 2021 12:00:57PM Subject: Topband Digest, Vol 228, Issue 4 Send Topband mailing list submissions to topband@contesting.com To subscribe or unsubscribe via the World Wide Web, visit http://lists.contesting.com/mailman/listinfo/topband /> or, via email, send a message with subject or body 'help' to topband-requ...@contesting.com You can reach the person managing the list at topband-ow...@contesting.com When replying, please edit your Subject line so it is more specific than "Re: Contents of Topband digest..." Today's Topics: 1. More radials towards EU (Ignacy Misztal) 2. Ground loop isolator that passes DC (Chuck Hutton) 3. Re: Ground loop isolator that passes DC (Jim Brown) 4. Re: Ground loop isolator that passes DC (Don Kirk) 5. Re: Ground loop isolator that passes DC (Richard Thorne) 6. Re: Ground loop isolator that passes DC (Jim Brown) 7. Re: More radials towards EU (John Kaufmann) 8. Re: Ground loop isolator that passes DC (Andrew Ikin) 9. Re: Ground loop isolator that passes DC (Frank Krozel) 10. Re: Ground loop isolator that passes DC (Jim Brown) ---------------------------------------------------------------------- Message: 1 Date: Fri, 3 Dec 2021 13:15:33 -0500 From: Ignacy Misztal To: topband@contesting.com Subject: Topband: More radials towards EU Message-ID: Content-Type: text/plain; charset="UTF-8" My shunt fed tower has 36 radials 70 to 100 ft long. Would adding a few longer radials towards EU help to EU? Eznec says no. Ignacy NO9E ------------------------------ Message: 2 Date: Fri, 3 Dec 2021 20:32:37 +0000 From: Chuck Hutton To: "topband@contesting.com" Subject: Topband: Ground loop isolator that passes DC Message-ID: Content-Type: text/plain; charset="iso-8859-1" Hi - Many years ago I saw some ground loop isolators that pass DC. That is exactly what I need so that power can be sent over coax feeds to preamp at the antenna. I cant find anything on eBay that mentions passing DC in an isolator. None of the isolators I have will pass DC. Does anyone know an isolator that passes DC? I would like to avoid building one. Chuck ------------------------------ Message: 3 Date: Fri, 3 Dec 2021 13:14:56 -0800 From: Jim Brown To: topband@contesting.com Subject: Re: Topband: Ground loop isolator that passes DC Message-ID: Content-Type: text/plain; charset=UTF-8; format=flowed On 12/3/2021 12:32 PM, Chuck Hutton wrote: > Many years ago I saw some ground loop isolators that pass DC. There ain't no such thing as a "ground loop." It's a faulty concept, and using it to solve a problem are a bad idea. Most problems blamed on "ground loops" are the result of a failure to follow proper grounding and bonding practices. What problem are you trying to solve? 73, Jim K9YC ------------------------------ Message: 4 Date: Fri, 3 Dec 2021 16:21:25 -0500 From: Don Kirk To: Chuck Hutton Cc: "topband@contesting.com" Subject: Re: Topband: Ground loop isolator that passes DC Message-ID: Content-Type: text/plain; charset="UTF-8" Hi Chuck, Based on the application you mentioned, I suspect you?re looking for commercially available bias tees. MFJ sells Bias Tees. Don (wd8dsb) On Fri, Dec 3, 2021 at 3:33 PM Chuck Hutton wrote: > Hi - > > Many years ago I saw some ground loop isolators that pass DC. > > That is exactly what I need so that power can be sent over coax feeds to > preamp at the antenna. > > I cant find anything on eBay that mentions passing DC in an isolator. > None of the isolators I have will pass DC. > > Does anyone know an isolator that passes DC? I would like to avoid > building one. > > > Chuck > > > _________________ > Searchable Archives: http://www.contesting.com/_topband [1] - Topband > Reflector > ------------------------------ Message: 5 Date: Fri, 3 Dec 2021 15:34:32 -0600 From: Richard Thorne To: topband@contesting.com Subject: Re: Topband: Ground loop isolator that passes DC Message-ID: Content-Type: text/plain; charset=UTF-8; format=flowed I 'think' what Chuck is trying to do is install? a lightening protector at his coax entrance panel. The problem with lightening protectors is the blocking of DC and you can't send voltage to the switch, pre-amp or what ever your trying to power over the coax. My solution, good or bad, was to install a box outside my shack that includes a 12v power supply and the bias T.? I inserted the bias-t on the antenna side of my lightening protectors.? Inside the box I have an aluminum plate which is grounded to my system ground.? If I can I'll post a picture as it shows how items are attached to the aluminum plate. Rich - N5ZC On 12/3/2021 2:32 PM, Chuck Hutton wrote: > Hi - > > Many years ago I saw some ground loop isolators that pass DC. > > That is exactly what I need so that power can be sent over coax feeds to preamp at the antenna. > > I cant find anything on eBay that mentions passing DC in an isolator. None of the isolators I have will pass DC. > > Does anyone know an isolator that passes DC? I would like to avoid building one. > > > Chuck > > > _________________ > Searchable Archives: http://www.contesting.com/_topband [2] - Topband Reflector ------------------------------ Message: 6 Date: Fri, 3 Dec 2021 14:49:08 -0800 From: Jim Brown To: topband@contesting.com Subject: Re: Topband: Ground loop isolator that passes DC Message-ID: Content-Type: text/plain; charset=UTF-8; format=flowed On 12/3/2021 1:34 PM, Richard Thorne wrote: > The problem with lightening protectors is the blocking of DC and you > can't send voltage to the switch, pre-amp or what ever your trying to > power over the coax. There are protectors that don't block DC. A study of mfr catalogs will find them. 73, Jim K9YC ------------------------------ Message: 7 Date: Fri, 3 Dec 2021 18:26:25 -0500 From: "John Kaufmann" To: "'Ignacy Misztal'" , Subject: Re: Topband: More radials towards EU Message-ID: Content-Type: text/plain; charset="us-ascii" EZNEC is correct. Adding more radials, even long ones, in a specific direction won't preferentially favor the direction in which the radials are added. It will help raise the overall efficiency of the antenna to a degree, depending on how many radials are already in place, but any improvement will be distributed uniformly over all directions. 73, John W1FV -----Original Message----- From: Topband [mailto:topband-bounces+john.kaufmann=verizon....@contesting.com] On Behalf Of Ignacy Misztal Sent: Friday, December 3, 2021 1:16 PM To: topband@contesting.com Subject: Topband: More radials towards EU My shunt fed tower has 36 radials 70 to 100 ft long. Would adding a few longer radials towards EU help to EU? Eznec says no. Ignacy NO9E _________________ Searchable Archives: http://www.contesting.com/_topband [3] - Topband Reflector ------------------------------ Message: 8 Date: Fri, 3 Dec 2021 23:53:20 -0000 From: "Andrew Ikin" To: "Chuck Hutton" , Subject: Re: Topband: Ground loop isolator that passes DC Message-ID: Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Chuck Hutton, Wrote on Dec. 3. I guess what Chuck means, is a Ground loop due to the antenna end of the coax. screen being connected to Earth thus causing the feeder shield to become a loop antenna with the ground RF return path to Rx. Hence, resulting in excess noise pick-up. Normally common mode choke will be of benefit. But I would guess that Chuck has already tried this. One option could be fit a 1:1 isolation transformer at the Rx input or into the Bias T. Then use a floating power supply to the drive antenna pre-amp.. A bias T that already has a common mode choke on the DC input would help too. The Antenna Interfaces manufactures by Wellbrook have this choke feature. 73 Andrew Ikin G8LUG ------------------------------ Message: 9 Date: Fri, 3 Dec 2021 18:00:13 -0600 From: Frank Krozel To: Andrew Ikin Cc: Chuck Hutton , topband@contesting.com Subject: Re: Topband: Ground loop isolator that passes DC Message-ID: Content-Type: text/plain; charset=us-ascii Are you thinking of a Bias-T? MFJ sells them with some of their tuners. -73- Frank KG9H kg9hfr...@gmail.com > On Dec 3, 2021, at 5:53 PM, Andrew Ikin wrote: > > Chuck Hutton, > > Wrote on Dec. 3. > > That is exactly what I need so that power can be sent over coax feeds to > preamp at the antenna. > I cant find anything on eBay that mentions passing DC in an isolator. None > of the isolators I have will pass DC. > Does anyone know an isolator that passes DC? I would like to avoid building > one.> > > I guess what Chuck means, is a Ground loop due to the antenna end of the coax. screen being connected to Earth thus causing the feeder shield to become a loop antenna with the ground RF return path to Rx. Hence, resulting in excess noise pick-up. > Normally common mode choke will be of benefit. But I would guess that Chuck has already tried this. > > One option could be fit a 1:1 isolation transformer at the Rx input or into the Bias T. Then use a floating power supply to the drive antenna pre-amp.. A bias T that already has a common mode choke on the DC input would help too. > The Antenna Interfaces manufactures by Wellbrook have this choke feature. > > 73 > > Andrew Ikin G8LUG > > _________________ > Searchable Archives: http://www.contesting.com/_topband [4] - Topband Reflector ------------------------------ Message: 10 Date: Fri, 3 Dec 2021 16:29:40 -0800 From: Jim Brown To: topband@contesting.com Subject: Re: Topband: Ground loop isolator that passes DC Message-ID: Content-Type: text/plain; charset=UTF-8; format=flowed On 12/3/2021 3:53 PM, Andrew Ikin wrote: > I guess what Chuck means, is a Ground loop due to the antenna end of the > coax. screen being connected to Earth thus causing the feeder shield to > become a loop antenna with the ground RF return path to Rx. Hence, > resulting in excess noise pick-up. A serious common mode choke at the feedpoint is critical for this, effectively disconnecting the coax shield from the antenna for common mode current. But proper grounding and bonding in the shack and throughout the home are critical -- a primary cause of RF in the shack is failure to do that. There are differences with practice in the UK and EU with respect to connection of earth electrodes. This set of slides shows proper implementation in North America, which properly considers both power and antennas with respect to lightning safety. The laws of physics don't change at the water's edge. :) http://k9yc.com/GroundingAndAudio.pdf /> 73, Jim K9YC ------------------------------ Subject: Digest Footer _______________________________________________ Topband mailing list Topband@contesting.com http://lists.contesting.com/mailman/listinfo/topband /> ------------------------------ End of Topband Digest, Vol 228, Issue 4 *************************************** Links: ------ [1] http://www.contesting.com/_topband [2] http://www.contesting.com/_topband [3] http://www.contesting.com/_topband [4] http://www.contesting.com/_topband _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector