The TZ-RD-1740 is a rotary dipole antenna designed to permit operation on the 6/17/40m bands. The antenna is primarily designed as a loaded 40m dipole. Careful design and extensive testing has allowed optimisation so that the antenna also operates most effectively on 6m and also 17m with no impact on the 40m operation. No traps are used in this antenna and on all but the 40m band it operates as a full size dipole or better. Additionally, if relays are installed across the loading coils the antenna operates as a full size dipole on 30m. An optional 12m critically coupled element may also be purchased than enables the antenna to be used as a full sized dipole on 12m as well.
When mounted at heights of 14m or higher, this antenna is an absolute gun for working DX on 40m. Results will surprise!
The antenna is full size on 30m and therefore has effectively 0 dBi gain on that band. Since loading is halfway along each element losses are minimised since the current in that antenna is much less than at the feed. For 40m the antenna is almost 3/4 of full size and performance is only slightly less than that of a full size antenna, without the mechanical difficulties. On 17m the antenna is a full size rotary dipole.
On 6m the loading coils are so sized and placed so that the antenna acts as 3/4 wavelength dipole on each side and therefore has a cloverleaf pattern. Although it has not got the gain of a yagi it allows operation on the “magic” band with little or no effort exhibiting some gain over a dipole. Gain on 6m is at 45 degrees to the line of the antenna and some 2-3dB over a dipole. Great for the sporadic E season in summer. Effectively, this antenna can be configured to operate on 5 different bands, 6m, 12m, 17m, 30m and 40m. As such, it is the perfect addition to the ham with a tower and an existing traditional 10/15/20m tribander.
BLOCK SIZE & MOUNTING CONSIDERATIONS
The TZ-RD-1740 can be mounted 1 or 2 meters above (parallel to the boom – i.e offset 90 deg) above your existing tribander to permit coverage of the Low bands or as a simple antenna for the new ham to HF operating. A turning radius of at least 7.5m is recommended as the total length of each side of the antenna is 7.1m (total 14.2m wing span).
The TZ-RD-1740 is designed as a high performance DX antenna for 40m and therefore needs to be mounted at height and in the clear. A minimum installation height of 10m is required, and for DX performance on 40m and installation height of at least 15m is recommended. Similar heights are recommended if operating the antenna with the loading coils shorted for 30m operation. FOr 6m, 12m (if option is selected) and 17m an operational height of 8m is acceptable. At 15m or greater the antenna will perform exceptionally well for DX communications.
ANTENNA DESIGN AND COMPONENTS
The TZ-RD-1740 uses 2 enameled copper wire loading coils that are not affected by rain since the coils sections are sealed. Acetal plastic insulating sections are used for mechanical strength and stiffness so that the antenna is subject to minimal sag. The center sections of the antenna are 32mm O.D, tapering down to 12mm O.D. at the tips . Stainless steel fasteners are used throughout as well as aluminum rivets for reduced corrosion. Four (4) stainless steel hose clamps are used to permit adjustment of the antenna on each band. Assembly is simple and straightforward, and if by chance something does go wrong most parts can be obtained from your local hardware store, e.g. nuts, crews, rivets, U bolts etc.
The Rippletech TZ-1840 balun is recommended for feeding the antenna with low loss across the bands.
The TZ-RD-1740 is supplied with all stainless steel hardware except for the boom/pole mount U bolts (optionally S/S).