Impedance Transformer

Optimized for connecting 50-ohm antennas and pre-amps to the high impedance Red Pitaya inputs. It improves sensitivity and overall receives performance.

Less than 1 dB insertion loss from 2-50 MHz.

Compatible with STEMlab 125-10 and 125-14.

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:

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

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):
- 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: