First Contact

I have had the first contact with the radio. I just solved the problem with the pll jitter.
It turned out to be bad connections and maybe a instable capacitor in the vco.
Then a fellow ham responded when I was testing.

Only the tx driver (30mWatt) was working and no antenna was connected.
The other station was only a few hundred meter away from my QTH.
Connecting a piece of wire to the driver boosted my signal to almost S9.
Great, the first contact has been made before construction has finished.

I bought a transformer for the power supply. It fits perfectly. However I may need a bit more current than this transformer can deliver. I will add add an extra power supply if necessary.

Next problems on the 'to be solved list':
-Increase high tones in the audio.
-Solve squelch problem. Spike noise is audible when squelch is closed.
-Solve s meter problem. When connecting a meter to the sensitivity of the receiver decreases.
I would like to show some pictures. Unfortunately my camera broke down.

pll jitter

This weekend I did some wiring.

The powersupply is still not in. I have no transformer that fits the box. It should be smaller than 4.5 cm.

TX driver and the RX work. However the PLL has more jitter than it had on the breadboard.
I have checked it using a scanner It makes craking noises. The 10.7 MHz modulator sounds Ok.
Tonight I'll have a closer look at it.

It takes more time than expected.

building the tin boxes in the 19inch box

Last night I built the tin boxes in the 19 inch box.
Then it was time to wire them. This took longer than expected. In fact it is still not finished.
To night I will try to finish it.

I build in some relays for switching between receive and transmit.

I had to solve a short circuit. It was quite hard to find. One of the screws made contact with a tin can mounted on the other side.

Next problem will be the power supply. Three voltages are needed 13.8V , 5V and 9.8 Volt.
The 9.8 Volt is for the PA module. This is non standard I suppose The PA module was designed to be fed from Ni cad batteries. I will have to build this power supply myself.

Holes in the box

19 April
I finnaly finished making holes in the 19 inch box. Now I can start builing the tin cans in the box.

Start of Blog

In this Blog I will describe the design and construction of a 144 MHz transceiver.
The goal is to build a FM tranceiver from scratch. The frequency range must be: 144 MHz to 146 MHz in steps of 12.5 KHz. It should be possible to use repeaters.
The frequency must be controlled by a PLL. A microcontroller will control the PLL.
Output power will be at least 5 Watt.


A prototype exists on a breadboard . Basically it works but it still needs a lot of work.

This picture shows the receiver (left), the modulator (middle) ,the PA (right) and the lowpass filter.

The picture shows the microcontroller (left), the PLL unit (middle) and the receiver (right).

These units including a power suppy will be build into a 19 Inch Box. I am not sure if the power supply will fit.