02-01-2019, 03:11 PM
Sorting through my junkbox today and what did I find?
Here's an example of a homebrew 23cm and 13cm transverter from the 1980's. This was based on a design by YU3UMV published in VHF-Communications 1986. The boards are fiberglass drawn freehand with a Dalo pen then etched. I count 23 x BFG96 transistors and a TP3020A in the 23cm PA.
There are two crystal oscillators (one for each band) running 30MHz and 32MHz crystal multiplied to 540MHz & 576MHz. Separate TX & RX converters take the appropriate LO and multiply for 144MHz in/out.
Oscillator and TX/RX switching is done with PIN diodes and is controlled by RF sense from what the author called a VOX board, not sequencer as we do today.
This builder removed some of the PIN diode switching and replaced it with a To Tsu (Tohtsu) relay. Next to the relay is a dual band stripline RF detector for reading TX power.
Just consider the effort and commitment both in time and dollars this fellow went to get on these bands. It's a lot different today.
I've posted this in several places basically for the sake of posterity because it will soon disappear from FB.
Here's an example of a homebrew 23cm and 13cm transverter from the 1980's. This was based on a design by YU3UMV published in VHF-Communications 1986. The boards are fiberglass drawn freehand with a Dalo pen then etched. I count 23 x BFG96 transistors and a TP3020A in the 23cm PA.
There are two crystal oscillators (one for each band) running 30MHz and 32MHz crystal multiplied to 540MHz & 576MHz. Separate TX & RX converters take the appropriate LO and multiply for 144MHz in/out.
Oscillator and TX/RX switching is done with PIN diodes and is controlled by RF sense from what the author called a VOX board, not sequencer as we do today.
This builder removed some of the PIN diode switching and replaced it with a To Tsu (Tohtsu) relay. Next to the relay is a dual band stripline RF detector for reading TX power.
Just consider the effort and commitment both in time and dollars this fellow went to get on these bands. It's a lot different today.
I've posted this in several places basically for the sake of posterity because it will soon disappear from FB.