Currently viewing the tag: "antennas"

New Radio Shack progress

By On · Leave a Comment · In Amateur Radio

Most of the cabling work is done. Electric power has been installed, 2x50A via shielded cable and over 20 circuit breakers. The Matrix Strip Line Antenna Switch has been connected, and receive antenna cabling is close to finished. The RX antenna patch panel is installed and connected. 8 receive antenna cables are routed from the patch panel into the Radio Shack and will be connected to a K9AY RAS8x2 receive antenna controller.

cabling
cabling

Equipment room cabling is progressing. The Matrix switch is connected and RX antenna patching is also complete. 2 x 50A Power has also been installed with shielded cabling.

48 Photos

Rhombic vs Log Periodic at 30M – Shootout

By On · 2 Comments · In Amateur Radio

During my Arctic Diamonds presentation on the CCF/OHDXF Ferry Cruise in January, – Tonno, ES5TV asked me whether I had any ”normal”  antennas to compare my rhombics with.   

My answer was a tongue-in-cheek reply to the effect that since I had unlimited space at my disposal, I wasn´t interested in limited space antennas.

A fellow Rhombic owner who indeed has such a comparison antenna sent me the following audio files which demonstrate the difference between the reception of  ”normal ”  antennas and Rhombics.

The first audio file is of TL0A an Amateur Radio Station located  in the Central African Republic, recorded using a huge Log Periodic at 30 meters height.  

Most Radio Amateurs would kill to have such an antenna ! :-)

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The second recording is made 3 minutes later, from the same location, but this time using a  Rhombic antenna to receive TL0A.

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A visual comparison of the two files  says more than a thousand words:

TL0A on LP antenna

TL0A on LP antenna

 

TL0A received with a Rhombic

TL0A received with a Rhombic

 

My Rhombic colleague commented as follows:

”… you will hear what a 30 meter high 6.5 dB gain antenna sounds like with a very wide radiation pattern. It is ideal to pick up all the noise and electrical storms in the equatorial noise zone.

The other recording is 3 minutes later,  with a Rhombic with 20 dB gain, 10 meters high, low take off angle- and a beam width of just 10 degrees. It is not so much that the signal is that much stronger, it is that the noise is that much less. Note the ease with which it is possible to pick up and follow S1 stations that are very weak.

A Rhombic is not just about the gain, it is much more about the noise which you Dont Get…”

 

I rest my case.


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Moving the King into position

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Today, with the help of Finnbjörn Bjarnason from Litlaeyri, I moved the King´s pole to Litlanes, it´s final resting place.

The King will support a transmit vertical similar to  Lazy H Vertical as described by N6LF for 160M and the antenna will be erected as close to the seaboard as possible.

This antenna uses top loading and elevated verticals.

The arrival of the King´s pole to Tálknafjörður by ship.

Finnbjörn from Litlaeyri and I transported the King across the mountain.

Litlanes is a small peninsula which juts into the sea on my property. Positioning a Low Band transmitting antenna there gives me tremendous gain for 180° of the horizon. The sea shore basically runs North/South, so the coverage of the antenna will be from 0° to 180°.

These are the photos taken today:
Photos by Finnbjörn Bjarnason, Litlaeyri

Beverage Antennas and Graves

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 Otradalur has been inhabited since the earliest settlement of Vikings in Iceland.    The nation converted to Christianity in the year 1000 and it is known that there was a church in Otradalur for over 700 years.   The Church was moved to Bildudalur village around 1907, I believe.

There remains a small graveyard on the property, which gives the place a very nice presence. 

In addition, it is believed that there is a heathen grave site near the sea shore.   

100kW Antenna Switch

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A Delta Electronics Model SLS-4M (4 transmitters by 7 antennas) will be installed in the new radio shack.
The switch weighs about 200 pounds.   More information can be found at Toronto Surplus .
The strip-line switch is a compact, remotely controlled, 50 ohm switch matrix for connecting any of a number of transmitters having power outputs of up to 10 kW average to any of a number of antennas.  The switch is based on a new design principle (1984) that permits an extremely compact system with excellent power handling capability, impedance and cross channel isolation characteristics.

The design of the switch makes it inherently impossible to connect one transmitter to another transmitter or two transmitters to one antenna.   An electrical interlock system is built into the switch so that power is removed from the active circuits associated with any switch before the switch operation can be made.  At the completion of the switching sequence the interlock circuit is rerouted and reconnected to protect the new active circuit.

I have now repaired the control cable and tested the unit with the local control unit and everything works perfectly.
Frequency Range:
DC to 300 MHz

Impedance:
50 ohms coaxial

Insertion VSWR:
1.10 maximum to 32 MHz
1.2 to 300 MHz

Power rating with unity VSWR

20 kW average, 100 kW peak to 32 MHz
5 kW average, 20 kW peak to 300 MHz

Cross Channel Isolation:
70 dB minimum at 32 MHz
55 dB minimum at 300 MHz

Terminations:
7/8” EIA male flange

The SLS-4M is supplied with rear mounted rotary actuators to provide automated operation.  The actuators operate from a 48 Vdc supply with a typical operate time of less than 200 msec.

I have the Local Control Unit which contains an interface to the RF switching matrix.  Matrix operate time is approximately 0.5 second after a selection is completed by depressing the ANT Select pushbutton.

My plan is to have 7 rhombics and 4 transceivers permanently connected to the switch – 40m, 20m, 15m and 10m operating positions will then be able to choose any of the 7 rhombic antennas instantly.
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Surplus Hardline Coax

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Today I received some surplus Hardline coax.  This will be used for the 700 meters (2300 feet) run to the planned 160M vertical antenna – N6LF Lazy-H.

heliax

 

heliax

 

heliax

 

heliax

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Communications Spacers

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Communications Spacers

PREFORMED™ Communications Spacers provide an inexpensive way of eliminating mid-span hits on open wire.

Spacers keep open wires in their place and prevent lines from “going dead” and momen tary shorts and crosses.

Made from rigid, solid 3/8″, high-impact, PVC, Communications spacers possess excellent strength properties. They are designed with a suitable inside diameter for direct application to mid-span locations, and are easily wrapped onto adjacent wires.

Further information may be found at the Preformed website ,  and the catalog of Communications Spacers may be found here.

preformed line spacers

More information about the Communications Spacers may be found here .

Photos of the feeder repairs may be found in my Gallery.

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