Elecraft PR6 - Manual (Page 4)

Page 4 PR6 6-Meter Receiver Preamplifier Owner’s Manua l
Figure 3. Jumper P2 Location.
Circuit Description
The schematic diagram of the PR6 is shown on the next page.
The Avago ATF34143 low noise PHEMPT was designed for the VHF through low microwave frequency
range. It is capable of providing high gain and exceptionally low noise figure in the 6 meter band.
In the PR6, the input L network and L4 in the source circuit provide a near optimum noise match to the
ATF34143 from the PR6 50 ohm input. R2 is provided to set the drain current and is factory adjusted.
The drain circuit is entirely resistive. The absence of reactive components helps to assure stability. The
zener diode, D2 does not conduct in normal operation because the voltage across it is approximately 4
volts. It is provided as a voltage clamp to assure that the drain voltage does not exceed device ratings
during adjustment of R2.
The remaining circuitry is provided to switch the PR6 in and out of the signal path and DC switching to
provide power and control.