Upgrading the 23cm Transverter
1 minute read
More Power on 23cm!
Along the way, it transpired that the isolation offered by the CX-120P relay in my 23cm transverter was not very good, only 29dB at 1GHz. So I hit on the idea that a PIN diode could be used to supplement whatever poor isolation the relay offered. In this case, a single series configured PIN diode giving in excess of 20dB insertion loss (isolation) is inserted between the relay and the input to the pre-amp.
Location of the PIN diode
Although really just an experiment at the time, adding the PIN diode came at an appropriate time since a friend very kindly donated a 30W 23cm PA in the form of a pair of M57762s to ‘the cause’.
I mounted the ‘new’ PA in the lid of the existing transverter and gave it a suitably large heat-sink. I also, for the first time employed an SEQ-3 sequencer from DB6NT. Off course, I had to remove the single ‘brick’ PA, leaving a huge unsightly hole in the rear of the transverter. I fashioned an aluminium plate to cover this hole and mounted the SEQ-3 on it, with an extra heat-sink for good measure. See below.
Left - All finished and tidied up! The pink ptfe wire and generous use of cable-ties is a consequence of 13 years working in defence electronics.
Right - OK, the heat-sink is almost as big as the box, but it was all that I had ... and it does need to dissipate around 50W. In this case, the heat-sink gets warm, but not so that a fan is required ... unlike my new 13cm transverter!