HFU HF Underground
General Category => General Radio Discussion => Topic started by: Matt285 on January 14, 2020, 2019 UTC
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Was curious if anyone copies stations from countries such as China, Korea, Philippines or any other Asian stations on the East coast. I know there would be an obvious advantage listening on the West coast for such stations. Just wanted to know. I tend to mainly pick up European, South/Central American, Caribbean and Canadian stations at my QTH here in Florida.
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I can periodically pick up N Korea on 6250 ~ 10:00z in the morning (it's weak and I have to listen in LSB mode when it's audible) & get decent to good reception of NHK at midnight (05:00z) on 6155.
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What Sealord said. You have to stay up late or get up early in the morning to catch them on the greyline. A loop really helps for greyline dx'ing the Asian stations.
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The further a tx is from the rx (as in near-antipodal work), the lower the angle of arrival of their sigs, so having something that responds well to low angle of arrival, ie a vertical, is a great help.
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Interesting point about using a vertical. I tend to stray away from them as a lot of people say 'They radiate poorly in all directions' I have used verticals for QRP portable ops with a bit of success. I have thought about adding one for various operation anyway. Im always welcome to another antenna in yard! Yes. I need to utilize Grey line better in general. It's a simple method, that just involves being in the shack at the right time. Any favorite sites for Greyline mapping? Yes I have used some, just curious if there are opinions on this. Thank as always!
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Set up one of your verts and see how it plays. Your greyline will be an hour or so before sunrise to an hour or a bit more after, same for sunset.
I had a sloper (vertical polarised) heading east and a horizontal firing east and west, often, especially at fade in/fade out one would often far outperform the other, to the point of the signal being unheard on one but good on the other until it was completely gone for the day.
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Interesting point about using a vertical. I tend to stray away from them as a lot of people say 'They radiate poorly in all directions' I have used verticals for QRP portable ops with a bit of success. I have thought about adding one for various operation anyway. Im always welcome to another antenna in yard! Yes. I need to utilize Grey line better in general. It's a simple method, that just involves being in the shack at the right time. Any favorite sites for Greyline mapping? Yes I have used some, just curious if there are opinions on this. Thank as always!
The folks claiming verticals suck are the same folks that use two radials on said antenna in a suburban lot with no view of the horizon, just the neighbors plasma tv, then wonder why the match sucks and is noisy as hell. I've had quite my fill of ham 'experts'.
The right tool for the right job...verticals really shine in a low noise environment with a clear shot to the horizon. They do not do well in a crowded suberbopolis. In such situations a mini whip or a loop is a much better choice.
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As a lifelong West Coaster who sometimes visits the East Coast, I sometimes am jealous of the East Coast's better reception of African/Middle East stations.
I didn't realize how much I take our morning reception of Asian stations (SO many CNR and CRI stations are audible most days before 10 a.m.) for granted out here.
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^^^^^ True, the 49 and 41 meter bands are packed with Chinese and other Asian stations in the mornings when conditions aren't dead. I've only heard Europe over the pole or when conditions were better (i.e. 6-7 years ago or more). Greece sometimes comes in on 9420 khz during the evening, however. How they do it when the rest of Europe is missing (even on the ham bands) is beyond me.
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I used to pirate with vert's and dx before and after the tx. The tropical bands were wide open an hour before you started hearing het's with other antennas.
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Yes, Asian stations are quite easy to hear on the east coast, just listen on the right frequencies at the right times. Mornings are very good right now on 49 meters, for example.
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The folks claiming verticals suck are the same folks that use two radials on said antenna in a suburban lot with no view of the horizon, just the neighbors plasma tv, then wonder why the match sucks and is noisy as hell. I've had quite my fill of ham 'experts'.
The right tool for the right job...verticals really shine in a low noise environment with a clear shot to the horizon. They do not do well in a crowded suberbopolis. In such situations a mini whip or a loop is a much better choice.
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This.
Phased verticals are the trick for me, even with neighbors all around - I had great success using an EWE antenna with just two 8' ground rods originally back in the day. Granted I was fortunate enough having two pine trees 15' apart that pointed towards Europe. I added a variable cap dead center of the top horizontal wire (I used lamp cord) and then using my palstar with batteries and earphones adjusted it for best S/N for even better perfomance.
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I am 15 miles off Long Island Sound, I have a son in Oakland, California. My antenna at home is 40 feet of copper wire running north/south facing due east - a dozen feet off the ground. Facing east, there is virtually nothing but a 660' hill about a mile away. When in Oakland, I'm using a portable with its included longwire.
The Asian based transmissions (including the BBC) are an easy catch in Oakland and seldom gets in Connecticut. Among my Oakland gets in (check shortwave section HFU posts) late April 2019: Radio Nikkea, Voice of Korea, RNZI, KBS, Voice of Korea, Voice of Vietnam, NHK, FEBC, Voice of the People, KNLS, and KCBS. I did find the European/African broadcasters and pirates almost nonexistent out there. However, Radio Habana Cuba boomed in 🙄.
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The folks claiming verticals suck are the same folks that use two radials on said antenna in a suburban lot with no view of the horizon, just the neighbors plasma tv, then wonder why the match sucks and is noisy as hell. I've had quite my fill of ham 'experts'.
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I like to explain the dipole/OCF vs. vertical decision as a trade off.
A vertical is horizontal dipole turned about its centre point. Because a vertical doesn't have that other 1/4 wave leg that a dipole has up in the air, you have to compensate with radials. A lot of radials.* Otherwise, it's just not the same and you are compromising the performance of the antenna.
Some folks can't put up a dipole for one reason or another. A vertical offers the opportunity to use fewer supports to get the radiating element up in the air and this may be of value to some. However, the trade off is that you have to be prepared to put in the radials. If you have the land available, this may be an acceptable trade off.
*The more the better and the incremental benefits diminish as more are added but the data I have seen says that there is an initial barrier to entry (or barrier to reap the benefits) and that seems to be around 10-12 radials, at a minimum.
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I use 8 on my portable antennas as anything more in the field does little to improve performance, only adds setup time and p.i.a. factor. On a permanent setup, 16 is about the point of diminishing returns. At 8 radials, shifts in ground conductivity due to seasonal and weather shifts will be much more noticeable. On some models I've seen, the difference between 120 and 16 radials is a few db... not worth the trouble imho.
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An alternative to ground mounted/buried radials is to use elevated radials. The common lore is that 4 elevated radials will provide performance equivalent to 60 buried radials.
Things are usually not that easy though. N6LF has researched this in detail, and his recommendation is for 12 elevated radials. Still, you will need a boatload more buried radials for comparable performance to a vertical with elevated radials. You can read his extremely detailed analysis here:
https://rudys.typepad.com/files/elevated-ground-systems-article-final-version.pdf
If you are using a vertical with elevated radials for transmitting, you also have to be aware that there will be high voltages at the ends of the radials. You should also think about how you will address lightning protection for the elevated radial installation.
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Things are usually not that easy though. N6LF has researched this in detail, and his recommendation is for 12 elevated radials. Still, you will need a boatload more buried radials for comparable performance to a vertical with elevated radials.
This is what has stopped me from adding a vertical to my antenna farm. You need a lot of radials to get a good performing antenna (good performing relative to what I already have for antennas). A lot. I think about it from time to time (this discussion prompted that again). Then realize it is probably not worth the effort. I remain open to being convinced otherwise, however ;D
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FWIW, wwv is using 5 slanted radials in their systems.
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The feedpoint height is critical in the four elevated radiator verticals. Try to get it as close to 8ft. up as possible where it will match up with 50 ohm coax, no tuner needed. All the power goes into the radiator. For a low power SW pirate it's one of the best easy/ easy down antennas with some punch in your arsenal. I used them all the time.
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I did a quick web search and ran across a few possible articles of interest:
https://rudys.typepad.com/files/elevated-ground-systems-article-final-version.pdf
https://www.qsl.net/kk4obi/Elevated%20Radials.html
https://www.yccc.org/Meetings/presentations/2014/December/40M_V_Vertical_w_Elevated_Radials.pdf
https://www.w8ji.com/counterpoise_systems.htm
My own interest is receiving vs transmitting, losses are still important but perhaps not as critical? As I am in the middle of the python / KiwiSDR related programming I could only quickly glance at them, but they appear useful.
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Still, you will need a boatload more buried radials for comparable performance to a vertical with elevated radials.
Didn't realize that this was the case. I guess I now have some reading material for the weekend!
Elevated radials might not be practical in all back garden antenna installations.
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For the more permanent verticals, it may pay to drive a ground rod to the water table, if the table is within reach.
Suppose same could be said for any ground rod.
Keep in mind after a few inches below the surface there's no rf due loss, you might get more benefit if you buried the ground rod or wire horizontally and only an inch or two under the surface.
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^^^^^ True, the 49 and 41 meter bands are packed with Chinese and other Asian stations in the mornings when conditions aren't dead. I've only heard Europe over the pole or when conditions were better (i.e. 6-7 years ago or more). Greece sometimes comes in on 9420 khz during the evening, however. How they do it when the rest of Europe is missing (even on the ham bands) is beyond me.
The 170 kw Avlis signal is amazing. I can pick it up regularly on my 1940 Mantola tuber with an indoor 4 ft speaker wire that came with the radio from EBAY ($67 American......what a deal!!)