I began with an IF-loop on the rear-panel. The idea was to be able to test IF-filters and IF-amplifiers, or to do measurements as shown in the measurement pages. This, as many other projects, developed and probably there are new projects that will follow.
This was the first attempt and it’s not really a “split”, it should be called a “loop”.
The IF-output from the front-end, PB1746 – pin14, goes normally to the ”SSB IF-unit”, PB1778 – pin3. In the beginning I thought that it would be nice to be able to test other demodulators and therefore I put two more BNC-connectors on the rear-panel. I put the signal from the front-end board to the first BNC-connector and if I do not want to use this signal I just feed it back on the second BNC-connector. This also means that I do not have any phono-connectors left on the rear panel.
The IF-output is 10,7MHz and this output could also be connected to a short-wave receiver or a filter-bank, (?), and then into the transceiver again.
After the RS03-meeting in south Sweden, I decided that an IF-output would be more useful than a loop. Another reason was that I needed one more BNC-connector in the “dual tune” project.
The new idea is to use the IF that normally goes to the FM-unit and it’s NB-circuits. This output will be more broadband in the new front-end since this helps the NB-circuits. It’s also an advantage to have a more broadband output if one is interested to make a new demodulator. I must point out that I have not tested this with the original front-end since the signal-level will be lower. The new front-end contain an extra driver with more output power.
The signal that normally feed the “FM IF-unit”, pin 9, is now connected to a small passive splitter. This splitter feed the “FM IF-unit” with one output and the other goes to the BNC-connector.
This output can be used for feeding instruments, shortwave-receiver or a demodulator system as SM5BSZs LINRAD. The performance of this system together with SM5BSZs demodulators will not be as high as the performance with only SM5BSZ-modules, but it’s a nice and easy way to start if one would like to test some of his modules. With the FT225RD you don’t have to build all stages at one time. You will also be able to compare the performance of two systems at the same time, at least the IF-part and demodulator-part.
A good example is to use the SoftRock V7.0!