Posts by PA3AOD

I don't think it has to do with the power supply, otherwise there where more problems with the other semiconductors.

Maybe just one bad diode in the serie,

or maybe mechanical stress during placing who knows

Anyway my down converter works again and i hope it stays that way.

I don't think it is a production fault because it worked for a week without any problem.

The diode was just a short circuit (0 Ohm)

Anyway it works again that's make me happy

Hi all,

Update of my problem:

It's a pitty but they will not publish the circuit diagram for the "Universeller Empfang Mischer für QO-100" from Amsat-DL........

There is a way to get the schematic and that is reverse engineering, but it takes some time.

Luckily the main components are known and with the data sheet (LNBH26) from the manufacturer you can do a lot

The search for the fault as succeeded, one of the diodes at the output of the LNBH26 is shorted "0 Ohm" in both directions thats not good.....

But luckily the LNB26 has a built in protection for short circuit.

As you can see in the data sheet of the LNBH26 the diodes round the IC are not so critical.

By lack of a SMD diode i replaced it with a 1N5818 also a schottky diode.

The 14V is back and the converter is running now for a week without any problem.

Maybe one question remains, why did the diode fail?

Hi all,

My Amsat-DL "Empfangmischer" is broken (and that allready after a week use).

Is there maybe a schematic diagram available.

Version on the PCB is V3

Problem, the left LED is out the middle is on and the right one is blinking.

The 18V is on the Wide-band connector is good, but the 14V on the Narrow-band is missing.

Bert PA3AOD