The unit shown in the pictures is the previous 2-32MHz RF Switched version that can be transmitted through with 150W. RF switching will occur reliably with power as low as 500mW.

The unit is straight through with the power off.  With the power ON the relay is activated and the preamplifier is in line.  When RF is applied the switching circuitry deactivates the relay within 30mS and when the RF is removed the circuit holds the relay off for 500mS.  This prevents relay chatter when using SSB.  There is no provision for hard PTT switching.

This wideband preamplifier is preceded by a selection of four bandpass coupled pairs of tuned circuits that together with a variable capacitor tune 1.8-3.8, 3.8-7.6, 7.5-15.0, 15.0-30.0MHz.  

The HF Tuneable Receive Preamp comprises four bandpass coupled pairs of tuned circuits that together with a variable capacitor tune 1.8-3.8, 3.8-7.6, 7.5-15.0, 15.0-30.0MHz.  The fixed value of top coupling capacitor in conjunction with the wide variation of tuning capacitance across the bands causes the circuits to be slightly under-coupled at the low frequency end and slightly over-coupled at the HF end.

Gain specification.
The minimum gain is 12dB at the bottom of each of the four ranges, and 16dB at the top of each range.
The gain is adjustable over a wide range, mid-band A  -21 to +16dB, mid-band B  -28 to +16dB, mid-band C  -40 to +16dB, mid-band D  -30 to +16dB.

The fixed value of top coupling capacitor in conjunction with the massively varying tuning capacitance across the bands causes the circuits to be under-coupled at the low frequency band end and a bit over-coupled at the top end.

Connectors are SO239 unless otherwise requested.  There is also a 2.1mm DC connector and a twin red/black power lead 0.6m long to connect to a 13.5V bench power supply.