Today I became an owner of the nice thing - the power amplifier KL 144 designed and produced by RM Italy. I found it by the Internet so that I had no guarantee of its working state. The price was only 25 bucks so that I should not lose a lot.
The front view of the PA. It seems to be being used not very hard.
The top view. Some holes can be observed through the ribs of the heatsink.
The rear view. A lot of the dust appeared...
The power cord is in the awful conditions. I have to make it beautiful!
Now it is beautiful. I'm using the same kind of connectors I have used before to unify my equipment. The same connectors I've used with Icoms.
I connected the device to the accumulator and it seems to be working. The next step is to check whether it works in the passthrough mode.
I connected the TX connector of the PA to my VNA and the ANT connector the 3-element Yagi for 144 MHz. As you can see the VNA can't see the antenna - the SWR is about 51. This means that the passthrough mode does not work.
Well, I suspected something like this. Now it's time to open the lid and take a look under the hood. Everything looks fine.
I removed the screws used to join the lid and the PCB together. The bottom side is green. Also, I realized that the ground is passed from the connector to the flange of the output transistor and the soldered copper tube in the very middle of the PCB. I hope that the connection to the ground won't lose, ever.
I checked all the vias on the way from input to output and found the absence of the connection there. Five minutes later everything is fine - the Ohmmeter showed 0.2 Ohms between central wires of input and output connectors. I assembled the PA back, restored the connections between antenna and PA, PA and VNA ad turned it on. The picture below displays the positive result - the SWR is less than 1.1.
And one more picture. Just the curve of the SWR. Now the passthrough mode works properly.
To check if everything is really working properly I have to prepare my 250 watts dummy load and make the following chain: mobile radio switched to 2 watts -> PA -> VHF power meter -> dummy load. Pushing the PTT button should show the current state of affairs. But this should happen slightly later, as soon as everything is ready...
The front view of the PA. It seems to be being used not very hard.
The top view. Some holes can be observed through the ribs of the heatsink.
The rear view. A lot of the dust appeared...
The power cord is in the awful conditions. I have to make it beautiful!
Now it is beautiful. I'm using the same kind of connectors I have used before to unify my equipment. The same connectors I've used with Icoms.
I connected the device to the accumulator and it seems to be working. The next step is to check whether it works in the passthrough mode.
I connected the TX connector of the PA to my VNA and the ANT connector the 3-element Yagi for 144 MHz. As you can see the VNA can't see the antenna - the SWR is about 51. This means that the passthrough mode does not work.
Well, I suspected something like this. Now it's time to open the lid and take a look under the hood. Everything looks fine.
I removed the screws used to join the lid and the PCB together. The bottom side is green. Also, I realized that the ground is passed from the connector to the flange of the output transistor and the soldered copper tube in the very middle of the PCB. I hope that the connection to the ground won't lose, ever.
I checked all the vias on the way from input to output and found the absence of the connection there. Five minutes later everything is fine - the Ohmmeter showed 0.2 Ohms between central wires of input and output connectors. I assembled the PA back, restored the connections between antenna and PA, PA and VNA ad turned it on. The picture below displays the positive result - the SWR is less than 1.1.
And one more picture. Just the curve of the SWR. Now the passthrough mode works properly.
To check if everything is really working properly I have to prepare my 250 watts dummy load and make the following chain: mobile radio switched to 2 watts -> PA -> VHF power meter -> dummy load. Pushing the PTT button should show the current state of affairs. But this should happen slightly later, as soon as everything is ready...
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