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Transmitting on 2200 meters using WSPR Digital mode. 

WH2XND 137.575 KHz

WH2XXP 137.507 KHz

Antenna is Voice of America.


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The Remote Tuner For

475 KHz - First Attempt

I started my 475 KHz experiment by modifying a 160 meter four wire vertical cage remote tuner. The four foot square cage antenna is supported three feet off the east side of the tower at 95 feet. Located 15 feet above the cage is a 12-foot diameter aluminum tube capacitance hat. Two 12 X 6 inch diameter 300 uH coils were used for the matching inductance. Both coils are in series and mounted on top of the remote tuner enclosure.  Coax is fed from the shack with its shield bonded to the 200 plus radials, along with several ground rods used for tower lighting protection. The remote tuner was modified with additional Sangamo mica transmitting capacitors and one roller inductor that was used as an adjustable shunt for 50 ohm impedance matching. The 160 meter four wire cage vertical was only used for a short period of time as coupling to the tower during high winds created a high SWR.

The testing of 475 KHz continues with a 220'  (non-resonant) dipole fed with 300 ohm ladder line. The non-resonant dipole is attached to the tower by use of a 10 foot section of 1.5 inch solid fiberglass rod. By tying both of the ladder line conductors together it is now configured as a Marconi 'T',  with the other half of the antenna being the radials and ground rods. Both of the original 300 uH coils were used for loading. With the use of the dipole, the SWR is considerably more stable than with the vertical cage. The Aim-4300 antenna analyzer is used to collect all antenna data recorded. Array Solutions carries the entire line of Aim products. The Marconi antenna now has 800 ft. of top loading.

Testing on 137 KHz 5 smaller coils used!
A different configuration for 137 KHz only one coil in use!
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75.5 KHz 5.1 mH required to resonate

Five coils in series for 75.5 KHz ! Coil enclosure now has side panels as seen in our Photo Gallery.

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Coil Configuration For 69.8 KHz

The 475 KHz "Loaded Dipole Project" coils really came in handy for LF testing.  Both are held in mid-air using a one inch thick piece of polycarbonate  material. The total inductance is now 7.2 mH!

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Remote Tuner For 75 KHz

The remote tuner uses 60 nF of capacitance for tuning. The white mounting material used for mounting the capacitors and other components is a one inch thick UHMW polyethylene.  This stops high voltage arcing to the steel back panel in the  enclosure. I hope you enjoy the Photo Gallery.  

Thanks for stopping by.  


MF-LF sites of interest:

WEB - "The VE7SL Radio Notebook":  

VE7SL BLOG - "Homebrewing and Operating Adventures From 2200m to Nanowaves":

75, 137 & 475 KHZ PHOTO GALLERY

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