70cm Band

This chapter descibes all kind of developments that I have gone through the past couple of years for the 432MHz band. Many projects have been closed succesfully, others have been closed prior due to not being of interrest anymore or others ideas found of better match to the need.

Almost all subjects have as far as possible being photographed. This enables me to make things more clearer to the reader. In case things are not fully clear, please take some time to ask additional information by using the e-mail address found under "contact me". I will then try the clear things out as soon as possible.

My 432MHz station uses a Kewood TS811e transceiver, modified to use seperated TX and RX cabling.

432MHz PreAmp:
Because of long cabling between transceiver and antenna, and the need to have a sensitive receiption, there is a PreAmp mounted close to the antenna. For a long time I used a PreAmp like shown under link to DJ9BV Preamp.
Later I decided to improve the PreAmp for noise-figure and build the unconditional stable LNA designed by DJ9BV (see link to the left).
This new PreAmp consists of a resonator line made from a brass plate instead of the round tube in the old one. Both PreAmp's uses a MGF1302 FET as active device.

432MHz Power Amplifier:

My current 432MHz GS35b cavity is build around the russian GS35b.This tube is fitted in a cavity that has been been build by various HAM's already. The exact dimensions were difficult to find, but by means of some scaling from internet pictures and some guessing, the results were OK...

This GS35b tube is supplied by means of a dedicaded GS35b Power-Supply (link to the left). This PSU is build from components that is a mix of newly purchased and components found on different HAM-fests. Looking for the right components, not only for the PSU, but also for the GS35b Cavity can take sometimes over half a year. Completing such a 432MHz amplifier takes up to one year if one is not willing to build up using only new purchased components.

TTE1482e, a 200W, 432MHz Transistor Power Amplfier:

A while ago, prior to the choice to build a tube amplifier for 432MHz, I experimented with coupling four transistorized power-amplifiers. These amplifiers were Motorola TTE1482e brick's. Each of these amplifiers were rated at 200W each, consuming 15V/30A per unit. Read the story and see the pictures in the link to the left.