DX Engineering THUNDERBOLT DXE-MBVA-1UP, Руководство пользователя

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Your coaxial cable from the radio connects direct to the SO-239 connector on the DXE-UN-43
UNUN. Weatherproof this coaxial connection using TRM-06132 - Scotch® Super 33+ and DXE-
3M2155 - 3M Temflex™ 2155 Rubber Splicing Tape.
160 Meter Notes
Let's look at 160 meters in more detail. A 43 foot vertical antenna is a short antenna for 160, but it
will get you on the air. In this instance, coaxial cable type is a very important item to consider. DX
Engineering recommends a length of 150 feet of
DXE-213U an RG-213/U to give most tuners the
ability to match the antenna on the lower frequency bands where most tuning problems are
encountered. One needs to examine the complex impedance (R ± j) to see the problem.
On 160 meters, the use of 150 feet of polyethylene dielectric cable (such as
DXE-213U which has a
Velocity Factor of approximately 0.66) will transform the 2 – j183 impedance at the output of the
UNUN to a more tunable 38 + j180 at the tuner.
On the other hand, if you were to use 150 feet of coaxial cable that has a Velocity Factor of 0.85
(like foam dielectric LMR-400), the impedance on 160 meters would be transformed to only 3.5 +
j45 – still too low an R value for many tuners. In order to achieve the recommended results, the
LMR-400 length would need to be approximately 190 feet.
In general - the higher the R value, the easier it will be for the tuner to match the antenna system to
your transceiver.