FM deviation increased

Last night I was able to get more deviation by enlarging the coil in the super vxo. It was difficult to get both a correct center frequency and sufficient deviation.

I also removed a transistor that was supposed to work as a varicap. I even forgot it was in. It is probably something that I forgot to remove.

Now the audio sound much louder on a FM receiver. The sub audio tones still work.

subtones and repeater

I just finished the subtone generator. It worked the first time.ctcss encoder

Last night I build it in the transceiver. First test were unsuccessfull. It turned out that it was connected to an incorrect point in the modulator. It was easy to solve. Now it works, I can open the repeater PI3BRD in Breda. This repeater uses needs a 71.9Hz subtone. I might install a switch to switch between two subtones.
A tone of 88.5 Hz is needed for PI3BOZ. Unfortunately the receiver lacks sensitivity to use this repeater. PI3BOZ can be used using my FT-8700 though.

A problem is that the TX can transmit when the PLL is not in lock. That is a problem for repeater operation. The frequency of the PLL changes while switching between TX and RX. To solve this problem I have two options. First one is to build a in lock detector. Second option is to delay switching on the TX.

progress

I bought a CTCSS kit on ebay. It has not arrived yet. Building/programming one myself should not be a problem, it just takes some time. I want continue with other projects so I took a shortcut.

I will do some experiments with a new 10.7 MHz modulator. The goal is to build a modulator with a higher deviation. I will keep the existing one for FM narrow. The new one will be for FM normal. It is quite difficult to get sufficient deviation and keep the center frequency on 10.7 MHz. Some old Ham radio equipment use the same concept so it is possible.

The xtal IF filter used is 25 KHz wide so I should support FM normal.