Impedance Transformer

The Red Pitaya 14:1 Impedance Transformer is optimized for connecting HF antennas to the STEMlab 125-10 and STEMlab 125-14 boards. Steps up 50-ohm antennas and pre-amps to the high impedance inputs. Improves sensitivity and performance. Less than 1 dB insertion loss from 2-50 MHz.

How to use

• Place a jumper across pins 2 and 5 of each input to bypass the internal attenuators, then connect the transformer:
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Features

• Gold-plated male and female SMA connectors
• Shrink-wrap insulation
• Small and compact, room for one on each of the two antenna inputs
• Low insertion loss using a MiniCircuits® T14-1 wideband step-up RF transformer
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One example of Improved Performance

• • Using a passive antenna (VE3DO loop) with a Clifton Labs Z10042 11 dB Norton amplifier connected directly to a Red Pitaya at N6TV, strong intermodulation from two nearby FM broadcast stations on 92.3 and 106.5 MHz was clearly visible (106.5 - 92.3 = 14.2 MHz):
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  • Inserting the 14:1 transformer between the pre-amp and the Red Pitaya reduced the intermodulation significantly, and atmospheric band noise (wideband sensitivity) improved by about 4 dB:
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