Ten-Tec: 238C High Power Tuner

238C High Power Tuner

238C HIGH POWER TUNER
WITH CROSS NEEDLE PEAK READING WATT/SWR METER
Only $ 795.00

New from Ten-Tec! Model 238C now features a large cross-needle SWR and peak reading power output meter. Model 238C uses our tried and true “L” match design used in the earlier 238/238A/238B models with a new cosmetic design, larger heavy duty tuning capacitor than the original and backlit cross-needle SWR and peak power output metering. The 238 was rated the LOWEST INSERTION LOSS of any high power antenna tuner available by the ARRL Lab in their survey article comparing the Amateur Radio tuner market (QST 2/03). This same low-loss L network circuit is still used in Ten-Tec’s new model 238C. 238C is backed with a THREE YEAR parts and labor warranty! The 238C’s multi-function cross-needle SWR/wattmeter measures average or peak forward power in 200 or 2000 watt switchable scales. Four position antenna switch. All four positions have SO-239 output connectors for 50 ohm feedlines or position #4 can be used to feed balanced ladder line with standard 4:1 matching balun internal to tuner. Heavy duty hand built 3.5 kV variable capacitor, 18 uH silver plated hand-built roller inductor. 11 position center switch to set tuner configuration. BYPASS mode operable in all four antenna positions.

The matching circuit used in the model 238C is basically an “L” network. The “L” network has several advantages over other circuit configurations. It has only two adjustable parts, one inductor and one capacitor; most other networks use three. Because there are no internal nodes in the network, the maximum circuit voltages and currents which occur are never more than those present at the input or output terminals. With only two variable components, there is only one setting of each which will provide a perfect match to a given load impedance. This unique setting automatically provides the lowest Q network possible. Low Q means low circulating currents, hence low loss, and it also provides the widest frequency bandwidth of operation before retuning is necessary (very useful if you’re moving up and down the SSB portion of the band, for example). Finally, since the inductor is always series, the network always provides a two-pole lowpass response to provide harmonic rejection.

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