VK1EA
03-28-2019, 07:26 AM
Hi Islanders,
I was given the opportunity of buying a cheap faulty Hercules II and having it shipped to VK. The original idea was to keep just the low pass filter module (discarding the rest) and then fitting an EB-104 amplifier kit I finished not long ago.
Well, the temptation of fixing the amplifier was very high so the other day I acquired two large power supplies they had on special at a local electronics' shop and the fun began.
At first I applied DC power just to the control circuits and I measured a current consumption of 5A... that could not be normal. Few seconds later I saw a plume of smoke departing the control board: one of the IC sockets had melted.
So I fitted a new IC (and socket) and got ready for further tests. With the control board fixed (sort of) I applied low power from a QRP radio (like 8W or so).
Well, the amplifier was draining 40A for just 130W of RF. One of the RF pallets has at least one of the transistors broken, so lots and lots of RF power is being dissipated in the adsorption loads (the ones connected to the RF power combiners). I have to investigate why the unbalance alarm did not get triggered.
I'll post some photos:
https://i.postimg.cc/mtbh8tqB/IMAG0964.jpg (https://postimg.cc/mtbh8tqB)
https://i.postimg.cc/sMLXjK2g/IMAG0965.jpg (https://postimg.cc/sMLXjK2g)
https://i.postimg.cc/Z9yqC39F/IMAG0966.jpg (https://postimg.cc/Z9yqC39F)
https://i.postimg.cc/f30c7BqV/IMAG0967.jpg (https://postimg.cc/f30c7BqV)
https://i.postimg.cc/n9TF6G5Z/IMAG0970.jpg (https://postimg.cc/n9TF6G5Z)
https://i.postimg.cc/87cBc1hB/IMAG0971.jpg (https://postimg.cc/87cBc1hB)
I was given the opportunity of buying a cheap faulty Hercules II and having it shipped to VK. The original idea was to keep just the low pass filter module (discarding the rest) and then fitting an EB-104 amplifier kit I finished not long ago.
Well, the temptation of fixing the amplifier was very high so the other day I acquired two large power supplies they had on special at a local electronics' shop and the fun began.
At first I applied DC power just to the control circuits and I measured a current consumption of 5A... that could not be normal. Few seconds later I saw a plume of smoke departing the control board: one of the IC sockets had melted.
So I fitted a new IC (and socket) and got ready for further tests. With the control board fixed (sort of) I applied low power from a QRP radio (like 8W or so).
Well, the amplifier was draining 40A for just 130W of RF. One of the RF pallets has at least one of the transistors broken, so lots and lots of RF power is being dissipated in the adsorption loads (the ones connected to the RF power combiners). I have to investigate why the unbalance alarm did not get triggered.
I'll post some photos:
https://i.postimg.cc/mtbh8tqB/IMAG0964.jpg (https://postimg.cc/mtbh8tqB)
https://i.postimg.cc/sMLXjK2g/IMAG0965.jpg (https://postimg.cc/sMLXjK2g)
https://i.postimg.cc/Z9yqC39F/IMAG0966.jpg (https://postimg.cc/Z9yqC39F)
https://i.postimg.cc/f30c7BqV/IMAG0967.jpg (https://postimg.cc/f30c7BqV)
https://i.postimg.cc/n9TF6G5Z/IMAG0970.jpg (https://postimg.cc/n9TF6G5Z)
https://i.postimg.cc/87cBc1hB/IMAG0971.jpg (https://postimg.cc/87cBc1hB)