Hi David, W0DF
It is a very old model of a 2 x 19 element yagi made by TONNA for 435 MHz more than 20 years ago. I have the original manual but I have never used this type of antenna. The computed gain claimed by Tonna at 432.0 MHz both for the E plain and the H plain is 16.20 dBi and the front-to-back ratio is -23.56 dB while the -3 dB beamwidth is 2 x 14.76 dB The distance between each first director and the respective folded dipole is such that the feed impedance is 50 ohm. This antenna do not make use of any 1/1 balun so that the inner conductor of the 50 ohm coax cable is directly connected to one side of the folded dipole and the braid is directly connected to the other side and this is bad to supply a balaced folded dipole to an unbalance feed line like a coax cable. The manual do not supply any information on how connect both coax cables to the folded dipoles for circular polarization RHCP or LHCP but you can get the necessay schematic diagram from any antenna-book.
73" de
i8CVS Domenico
----- Original Message ----- From: "David Fine" [email protected] To: [email protected] Sent: Wednesday, August 29, 2007 2:47 AM Subject: [amsat-bb] 70cm Antenna Ident
Can anyone help me identify the manufacturer of a used 70cm crossed yagi
that I picked up along with a Yaesu 5400B rotator system at a local hamfest. The antenna has a 12 foot 5/8 inch square boom (in two pieces), 19 elements horizontal, 19 vertical uninsulated through the boom, and folded dipole driven elements. There are two things that I believe make this antenna unique. The coax attaches to the driven element with push-on crimp terminals (UGH), and the directors and reflectors are held in place on the boom with "W" shaped stainless steel spring clamps that are pressed over the boom. The elements then pass through the clamps and the spring tension holds the elements in place. Does this sound familiar to anyone? Thanks for the help. W0DF
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