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Author Topic: Beverage on the Ground  (Read 628 times)
N7GCO
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Posts: 169




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« on: December 03, 2017, 03:01:37 PM »

How close to your transmit antenna can a Beverage on the ground be?
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KM1H
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Posts: 2644




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« Reply #1 on: December 03, 2017, 04:53:27 PM »

Up to the point it is adding too much noise.

I have 3 BOGs and two run under the 15' high elevated radials of a 75/80/160 sloping vertical. With the feed of the vertical decoupled with a lot of ferrite and the BOG's feedlines also decoupled they are nice and quiet. The pigtails at both ends are CATV quad shield RG-6 and the main feed of about 200' is 3/4" CATV hardline.

I ran a test with the BOG feedline disconnected and terminated in a 75 Ohm load and absolutely nothing was heard. I use quad shield CATV RG-6 for the pigtails at both ends and 1/2" CATV hardline for the main 700-750' runs back to the house. The BOGs and 5 regular 2 wire direction switching Beverages each use a homebrew high isolation remote switch.

The hardline was all free.

Carl
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KW4GT
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Posts: 78




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« Reply #2 on: December 03, 2017, 07:51:23 PM »



The hardline was all free.


You realize you're turning a lot of people green with envy right now.

I've been thinking about adding some receive antennas at some point in the future and would love to see a diagram of what you've got.
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“Anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that 'my ignorance is just as good as your knowledge.'” ― Isaac Asimov
KM1H
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Posts: 2644




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« Reply #3 on: December 04, 2017, 11:06:46 AM »

No diagram, just 5 acres of mostly woods plus a few hundred more behind me where I can run Beverages as long as no trees are cut and they are at least 10' high and there is nothing on the ground to trip animals or humans thus no BOGs back there.  Beverage radials are on the ground and then covered with leaves, branches, etc.That property has been in the family since 1896.

I have two hubs back at the property line that are remotely switched as mentioned above.

I make changes often and the only thing "permanent" are the 4 towers which are all concentrated in the first 250' from the street.



The hardline was from partial reels that were used for rebuilds or storm damage repair; it didnt pay to bring them back since the workers were private contractors that traveled all over the country.
Ask around and you can find it also as many have done. I started when the town was cabled around 1980 or so.

Carl
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K4SAV
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Posts: 2406




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« Reply #4 on: December 04, 2017, 11:12:05 AM »

BOGs and Beverages are very easy.  Both use the same circuit, although the impedances will be different.  The circuit for a single BOG is shown below.  If you want to create a hub and run several BOGs out from that hub, Put some relays at the point where the BOG wires enter the box, and switch them with a control cable.  I use CAT5 for the control cable.  You will need a choke on the control cable.  Keep the wires inside the hub between the relays and the BOG wire connections very short.  Capacitance between them will couple one BOG to another.

The biggest problem with BOGs is avoiding common mode problems.  BOGs are more susceptible than Beverages because their gain is lower.  Notice I use 2 ground rods at the coax end.  That helps with the common mode problem and it helps dump lightning induced voltages and currents on the feedline.  You might be able to get away without the second ground rod but it you have common mode noise problems it will be very difficult to diagnose it, and also lightning can easily take out the transformer if the feedline is long.  The 90 volt gas tubes are cheap and avoid the need for a large termination resistor.

On 160 when the band is very noisy I use about 12 dB preamp gain.  When the band is very quiet (not very often) I sometimes use up to 24 dB gain to hear the really weak ones.  Typically I use about 18 dB.

That small choke for the coax has an impedance of 6100 ohms on 1.8 MHz and 3000 ohms on 3.5 MHz.

Jerry, K4SAV

Edit: I you grabbed that schematic a little earlier, I made a small edit to it.

« Last Edit: December 04, 2017, 11:36:00 AM by K4SAV » Logged
K4SAV
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Posts: 2406




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« Reply #5 on: December 04, 2017, 12:06:43 PM »

I see I lost part of my schematic and that contained the choke info, and the edit time has passed.  Here it is again.
Jerry, K4SAV



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KM1H
Member

Posts: 2644




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« Reply #6 on: December 04, 2017, 05:03:11 PM »

Anyone serious about good 160 performance needs the ARRL pub by ON4UN, Low Band DXing, 5th Edition

Carl
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