Hello to you all,
I am at the moment building a 300 watt Tx for 136 Khz, so I need to consider
what to do about an Tx antenna for the band. I am receiving with a G3LNP
balanced loop & pre-amp.
My garden is quite small so the antenna will have to go upwards & give
consideration to my neighbours. I have a 30 foot mast with a 4 Mtr beam, a
VHF/UHF log periodic beam & VHF/UHF colinear vertical probably going up to
45 feet. I have thought of substituting these for a 6 foot x 2 inch
fibreglass pole on top of my mast & using a similar arrangement to that
described in the article by Alan Melia G3NYK & Finbar O'Conner EI0CF about
spiral top loading. I can also wind inductance on the fibreglass pole to
increase the top load inductance. What are your thoughts on this idea & if
it sounds ok should I place the additional inductance above or below the
spiral & if above what about an additional capacity hat on top of that. I
will feed the device with a sloping vertical wire or on stand offs to keep
the feed away from the mast & tuned at the bottom with a 12 inch diameter
coil & variometer arrangement.
Please give me your comments.
Regards
Gary (G4WGT)
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