V/U handheld transceiver to HF HAM bands TX, ideas for construction.
I am thinking of experimenting with a V/U transceiver (Kenwood TH-F7) for using it as a source to generate signals in the HF HAM bands.
I am not sure if I have asked this question before, but I am thinking of using a single MC12080 and play around with it's division ratio. This will cover the 160, 80, 40, 20 meters (VHF source) and 15 meters (UHF source).
Another way would be to have a 74f74 and using it as a quadrature divider, but this would require a big input signal range which is not available.
What other methods can I use and how to amplify the square wave output (class-E?)? These have to be small-sized, so I do not think if mixing down worths the effort.
You know that squarewave means harmonics at 3f, 5f etc. Have you planned to use a switchable low pass filter?
I was thinking of class-E amplifiers for this reason, apart from efficiency. The output filter will remove these harmonics.
At multiple bands it has to be switchable, which is hard and space consuming.
Even if class-A is used a switchable filter will be required (at the input in this case) to convert the square wave to sine, to be further amplified.
I am not sure which way is best.
Another way I see, is to mix down the VHF/UHF so a sine is produced. The problem with this aproach is that a stable V/U LO is needed. Maybe a ceramic resonator oscillator can be easily made using one of these PMR crystal resonators. The harmonics could be relatively easily removed after mixing with a single LPF (non switchable) for all bands, because of the high LO involved. This technique is similar to the analogue Spectrum analyzer operation.
Another thing could be to replace the ceramic resonator with a PLL IC for VHF, but I am not aware of such ICs.