I wanted to get on 6 meters, both for SSB and for local FM. I had a few items hanging around, did some quick math and decided to repurpose an M400 Starduster for both options. I call it the CloudDuster.
Inventory/ Parts List
(1) Sirio M400 Starduster Antenna - http://www.sirioantenne.it/starduster-m-400/
(1) MFJ-347 Dipole Mount - http://www.mfjenterprises.com/Product.php?productid=MFJ-347
(2) 3/8x24 Whip Mount - h**p://www.amazon.com/dp/B00HZ7SPBC/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=201VMU7Q9S093&coliid=I129R8IM4HMEZ0
(1) Antenna switch
(x) Various masts, PVC and mounting hardware.
Theory/Process
The Starduster is a 10/11 meter 1/4 wave ground plane antenna . The vertical and radial elements are comprised of 2 sections at ~1400 mm as listed in the manual. I refer to them as Primary and Secondary sections.
The primary radiator section is 55.875 inches long.
The secondary radiator section is not used for this project.
The primary radial section is 55.375 inches long.
The secondary radial section is 55.125 inches long.
Self I said - basic theory for 6 meter antennas, with a center frequency of 52MHZ tells me I can use these.
The vertical needs a 54 inch radiator and a 56.7 inch radial.
The dipole needs 2 54 inch rods.
Since I was focusing on two different areas of the band:
52.5 MHz FM = 53.486 in/56.160 in were my starting points for the radiator/radial pieces.
50.1 MHz = 56.0625 in per side.
In Practice
- The vertical
I built the 1/4 wave ground plane using the primary vertical at it's given length (I knew it was long but did not want to cut it yet). I used the primary and secondary radial sections to match dimensions commonly used for such antennas.
Testing confirmed that the antenna was too long, but it was close. and it was however close enough that my tuner could tune it where needed at the higher frequencies.
I had been reading a few articles that seem to indicate shorter radials also made the radiator appear shorter and not have a significant impact on gain. I was also looking at those secondary radial pieces and wanting to use them for a dipole, so I figured I would give it a shot. Removing the secondary radials did move the SWR curve to a higher frequency. The antenna SWR fell into a curve where my tuner was no longer necessary for the target frequency. I was able to make some local FM simplex contacts with it 10 feet off the ground.
I considered cutting the the vertical element to bring it closer to the desired frequency but decided to hold off until I had a chance to put it at the final location, which included the dipole below.
- The dipole
I took two of the three secondary radials, the MFJ mount and whip studs (ferrels) and made a dipole. It measured out fine. 1:1 at 10 feet from the ground.
In Position
I attached the vertical to a vent pipe on the roof providing 25 feet of elevation to the feedpoint. I mounted the dipole a couple of feet below the bottom of the radial at about 18 feet. They are not quite above the roofline so that does have some impact. I check the SWR figures and attached them to an antenna switch and that to the radio. The tuner on the radio switches to pass through over the 50-54 MHz spread. So know I have both vertical and horizontal options for 6 meters. I may eventually cut the radiator and fine tune as I know it is long. I'll post some figures and performance notes in Part 2 and also await feedback.
In Closing (of Part 1)
I took the primary elements of an M400 Starduster and made a 6 meter 1/4 wave ground plane. I took two of the secondary elements of the same antenna and made a dipole that mounts below. That is my 6 meter "CloudDuster" project.
Inventory/ Parts List
(1) Sirio M400 Starduster Antenna - http://www.sirioantenne.it/starduster-m-400/
(1) MFJ-347 Dipole Mount - http://www.mfjenterprises.com/Product.php?productid=MFJ-347
(2) 3/8x24 Whip Mount - h**p://www.amazon.com/dp/B00HZ7SPBC/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=201VMU7Q9S093&coliid=I129R8IM4HMEZ0
(1) Antenna switch
(x) Various masts, PVC and mounting hardware.
Theory/Process
The Starduster is a 10/11 meter 1/4 wave ground plane antenna . The vertical and radial elements are comprised of 2 sections at ~1400 mm as listed in the manual. I refer to them as Primary and Secondary sections.
The primary radiator section is 55.875 inches long.
The secondary radiator section is not used for this project.
The primary radial section is 55.375 inches long.
The secondary radial section is 55.125 inches long.
Self I said - basic theory for 6 meter antennas, with a center frequency of 52MHZ tells me I can use these.
The vertical needs a 54 inch radiator and a 56.7 inch radial.
The dipole needs 2 54 inch rods.
Since I was focusing on two different areas of the band:
52.5 MHz FM = 53.486 in/56.160 in were my starting points for the radiator/radial pieces.
50.1 MHz = 56.0625 in per side.
In Practice
- The vertical
I built the 1/4 wave ground plane using the primary vertical at it's given length (I knew it was long but did not want to cut it yet). I used the primary and secondary radial sections to match dimensions commonly used for such antennas.
Testing confirmed that the antenna was too long, but it was close. and it was however close enough that my tuner could tune it where needed at the higher frequencies.
I had been reading a few articles that seem to indicate shorter radials also made the radiator appear shorter and not have a significant impact on gain. I was also looking at those secondary radial pieces and wanting to use them for a dipole, so I figured I would give it a shot. Removing the secondary radials did move the SWR curve to a higher frequency. The antenna SWR fell into a curve where my tuner was no longer necessary for the target frequency. I was able to make some local FM simplex contacts with it 10 feet off the ground.
I considered cutting the the vertical element to bring it closer to the desired frequency but decided to hold off until I had a chance to put it at the final location, which included the dipole below.
- The dipole
I took two of the three secondary radials, the MFJ mount and whip studs (ferrels) and made a dipole. It measured out fine. 1:1 at 10 feet from the ground.
In Position
I attached the vertical to a vent pipe on the roof providing 25 feet of elevation to the feedpoint. I mounted the dipole a couple of feet below the bottom of the radial at about 18 feet. They are not quite above the roofline so that does have some impact. I check the SWR figures and attached them to an antenna switch and that to the radio. The tuner on the radio switches to pass through over the 50-54 MHz spread. So know I have both vertical and horizontal options for 6 meters. I may eventually cut the radiator and fine tune as I know it is long. I'll post some figures and performance notes in Part 2 and also await feedback.
In Closing (of Part 1)
I took the primary elements of an M400 Starduster and made a 6 meter 1/4 wave ground plane. I took two of the secondary elements of the same antenna and made a dipole that mounts below. That is my 6 meter "CloudDuster" project.
Attachments
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