W5BIV
04-27-2009, 02:16 PM
I have been using the TENNADYNE® TD-90 terminated folded dipole for four months. It is a broadband antenna designed for fixed station, multi-frequency applications. This type of antenna is widely used by military, marine, commercial and broadcasting services. The antenna can be mounted horizontally between two support masts or structures, or as an inverted ‘V’ using a single central support mast, which is the configuration that I am using.
I have been very impressed with the construction of the TD-90. The antenna is made with extremely durable stranded copper clad steel and is pretuned so that no measuring or cutting is necessary. The components are also heavy duty construction. To date, it has easily withstood 65 mph winds.
I found it very easy to install and the performance has exceeded my expectations. The benefits of operating with a broadband antenna are numerous, particularly if you operate in a remote controlled configuration. Although the antenna is rated from 1.8 to 30 MHz, I found that it also loads well on 6 meters.
My initial concern with this antenna design was the anticipated loss of power in the terminating resistor, but that concern has been unfounded. The TD-90 is rated for 500 watts PEP and I routinely operate at that power level with little apparent heating of the terminating resistor.
I performed many on-air comparisons with the TD-90, resonant half wave inverted ”V”s, and a GAP Challenger vertical. Most stations could not detect any difference between the TD-90 and the resonant dipoles. The comparison with the vertical varied with the propagation angle, as would be expected. Another advantage of the TD-90 is the very low noise level.
As I operate phone and digital modes, the broad band characteristics of the TD-90 has been a joy to experience. Mine is mounted with the apex at 30 feet and the ends at 12 feet. There is a coax run of 60 feet to a remote coax switch, 30 feet to a grounded PolyPhaser lightning arrestor, and 15 feet to the rig.
I measured the VSWR on all bands with an RF Applications P-1500 digital RF power and SWR indicator. Findings were as follows:
1.8 to 2.0 MHz 1.1:1
3.5 to 4.0 MHz 1.1:1
60 meters 1.1:1
7.0 to 7.3 MHz 1.4:1
10.1 to 10.15 MHz 1.1:1
14.0 to 14.35 MHz 1.1:1
18.07 to 18.16 MHz 1.5:1
21.0 to 21.45 MHz 1.3:1
24.9 to 24.99 MHz 1.1:1
28.1 MHz 1.8:1
29.7 MHz 1.3:1
50.1 MHz 1.4:1
53.9 MHz 1.2:1
The SWR readings on my Icom 756PROIII agreed with the readings on the P-1500.
I highly recommend this antenna to anyone needing a dependable, broad band antenna.
Steve Pierce, W5BIV
I have been very impressed with the construction of the TD-90. The antenna is made with extremely durable stranded copper clad steel and is pretuned so that no measuring or cutting is necessary. The components are also heavy duty construction. To date, it has easily withstood 65 mph winds.
I found it very easy to install and the performance has exceeded my expectations. The benefits of operating with a broadband antenna are numerous, particularly if you operate in a remote controlled configuration. Although the antenna is rated from 1.8 to 30 MHz, I found that it also loads well on 6 meters.
My initial concern with this antenna design was the anticipated loss of power in the terminating resistor, but that concern has been unfounded. The TD-90 is rated for 500 watts PEP and I routinely operate at that power level with little apparent heating of the terminating resistor.
I performed many on-air comparisons with the TD-90, resonant half wave inverted ”V”s, and a GAP Challenger vertical. Most stations could not detect any difference between the TD-90 and the resonant dipoles. The comparison with the vertical varied with the propagation angle, as would be expected. Another advantage of the TD-90 is the very low noise level.
As I operate phone and digital modes, the broad band characteristics of the TD-90 has been a joy to experience. Mine is mounted with the apex at 30 feet and the ends at 12 feet. There is a coax run of 60 feet to a remote coax switch, 30 feet to a grounded PolyPhaser lightning arrestor, and 15 feet to the rig.
I measured the VSWR on all bands with an RF Applications P-1500 digital RF power and SWR indicator. Findings were as follows:
1.8 to 2.0 MHz 1.1:1
3.5 to 4.0 MHz 1.1:1
60 meters 1.1:1
7.0 to 7.3 MHz 1.4:1
10.1 to 10.15 MHz 1.1:1
14.0 to 14.35 MHz 1.1:1
18.07 to 18.16 MHz 1.5:1
21.0 to 21.45 MHz 1.3:1
24.9 to 24.99 MHz 1.1:1
28.1 MHz 1.8:1
29.7 MHz 1.3:1
50.1 MHz 1.4:1
53.9 MHz 1.2:1
The SWR readings on my Icom 756PROIII agreed with the readings on the P-1500.
I highly recommend this antenna to anyone needing a dependable, broad band antenna.
Steve Pierce, W5BIV