[TowerTalk] info on TH7DX and similar
T. A. Russell
n4kg@juno.com
Wed, 20 Aug 1997 20:37:57 -0600
On Wed, 20 Aug 1997 18:44:19 -0400 Mike Walker
<mwalker@geronimo.Legato.COM> writes:
>At 06:33 PM 8/20/97 -0300, Luiz Felipe Valente Ceglia wrote:
>> Hi,
>>
>>Can you send me any information on HyGain's TH7 and maybe TH6 (is
>that
>>right?) antennas, as it's gain FB ratio, etc.
>>
>>Thanks,
>>
>>
>>--
>>Luiz Felipe Valente Ceglia - lceglia@terenet.com.br
>>http://www.terenet.com.br/~lceglia - TereNet Staff
>>Tel/Fax:+55-21-548-2918 - HamCall: PY1NB ex: PU1WLF
>>
>>
>>
>TH6:
>Gain
>10m 9.5db
>15m 8.5db
>20m 8.0db
>
>Front to Back:
>25db
>
>Boom Length 24 feet (7.31M)
>Turning Radius 20 ft (6.09M)
>
>Hope this helps...Mike VA3MW
>
>mwalker@interlog.com
>
At best, those gain figures are "optimistic". Most likely they
originated in the advertising department before computer
modeling was readily available.
A full size wide spaced 4 element monobander is capable of 9.5 dB
isotropic.
A full size wide spaced 3 element monobander is capable of 8.5 dBi.
A full size (.35WL boom) 3 element monobander is capable of 8.0 dBi.
These gain figures assume no interaction and of course no trap losses.
On 10M, the 15M director of the TH6 has some effect on forward gain
(approx -1 dB). Trap losses can approach 1 dB.
These adjustments should provide a more realistic upper bound for
the actual TH6 antenna gain. These lower but realistic gain figures
by no means discredit the performance of this well known tribander.
My own TH6 has performed effectively without failure and
NO MAINTENANCE for many years. (It is a good idea to
replace the plated nuts and bolts with stainless steel and
to tape the rubber trap end covers with Scotch 33 electrical tape
before installation!)
de Tom N4KG
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