The MHP 70 is an ultra low-noise Masthead-Preamplifier with coaxial relay changeover capable of handling SSB RF-Power levels of up to 1500 Watts (750W CW).
The integral coaxial-relays have successfully been tested up to 2 KW SSB and feature large gold plated contact areas with extremely low insertion loss (0.1dB). Double shielded Teflon coaxial cables are used in order to guarantee a low losses and a high power handling capability.
There is no RF-VOX and protection circuits in the MHP 70 or MHP70R so a sequencer such as the DCW 2004B or amplifier with integral sequencer MUST be used. However – from 2022 MHP units now have added amplitude limiting protection circuitry built in to protect against rf damage if the rig’s barefoot power beats the users sequencer. Previously it was compulsory to sequence the rig correctly (along with any linear amplifier) and this always posed problems when using data modes like FT8/JT65 etc where the rig was commanded to tx by software or a vox soundcard.
The new version MHP preamplifiers are now protected against this low power rf so making them much easier to install an operate and less prone to rf damage.
With the MHP70 power needs to be supplied by a separate feed – there is no BiasT option. Note this unit is NOT RF SWITCHED. The unit still needs to be sequenced correctly to ensure that the device is not damaged by QRO RF in the same way you would do with any non RF-switched masthead device.
Frequency range: 430-440 MHz
Noise figure typ.: <0.8 dB
Gain typ.: 21 dB
Max. power SSB/CW: 1500 / 750Watt
Insertion loss: 0.12 dB
Supply voltage: 13.8-15 V
Current consumption: 420mA
Max. Mast diameter: 58 mm