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BT-101 Astroplane copy
Hi all, recently I decided to downsize my antennas here for vertical use and it got me thinking how small an antenna I could get away with and yet still keep good results, I have had a few ariels up here including 1/2 wave end feds from venom and Sirio, a .64 Sirio Gainmaster and an Imax 2000.
Originally I planned to use a simple 1/4 wave ground plane antenna like the Starduster because I know they work well but saw knight's here in the UK had/has a limited supply of BT-101 astroplane copies, the copies are unbranded perhaps because of the original patent I don't know and are based on the CTE Topone which was a close copy of the original astroplane by avanti I think NOT TO BE CONFUSED WITH THE NEW SIRIO TOPONE! which is completely different.
The BT-101 is very light but the alloy is reasonably solid, certainly the strangest looking antenna I have erected! There were a few minor niggles like the top hat section, the grub screw that holds the rods on does not go tight enough to hold the second rod in place, I simply put a layer of tape around each side to stop those top hat rods sliding right out. Also I had to mount another pole for the BT-101 brackets, my mast is a 2 inch diameter pole and the BT-101s brackets are made for a 1.75 inch pole. I would recommend attaching some fishing wire around the base loop to the pole for support, there is no way that bottom loop section would last in the wind here without extra support.
I'm usually mounting beams and verticals, rotators, and multiple runs of heavy coax up the pole so it was a welcome relief to mount the 12ft long BT-101 as it's so light. The feed point is about 38ft up with the tip of the ariel at around 42 ft, i'm surrounded by hills and very large trees here so more height the better, i'm about 250ft above sea level but from the NE to the SE the land doubles in height within a few thousand yards, hopefully there will be some higher angle radiation also from this ariel to get over the hills for the local stuff in that direction.
Anyway it's early days for results, but so far I'm pleased with the few local (within 20 mile) stations i've worked signal wise, as for DX, well I've just worked 234 division on the last day of the activation so for DX it's looking good too!
I must say I had a problem with an s5 to s7 of noise with my last vertical (sirio GPA 1/2 wave) and I had a post about it on the forum, now whether that noise generator whatever it was has stopped or the BT-101 is simply not picking it up I don't know, if it's the case that it's simply not receiving the interference then I'll say this strange design is the quietest omnidirectional vertical I have used.
(Forum user name was previously - mikefox whiskey) - 68 FB750 - Pat
Kenwood TS870 - Centre fed balanced dipole - HPSD 2 element Moxon for 11m, vertical 'Ringo' for 11m.
14/Apr/2013, 12:11 pm
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