| W7DUD |
Rating:  |
2003-12-27 | |
| Two strikes, and that' it! |
Time Owned: more than 12 months. |
This is my personal experience with the Ameritron AL-572 amplifier.
Several years ago, I was excited about my return to Amateur Radio activity. I purchased a new Kenwood TS-570, a new vertical antenna, and a new antenna tuner.
After spending several months on CW, I decided to purchase an amplifier. I ordered a new Ameritron AL-572, and received it about a week later.
I was pretty excited as I unpacked the amp, and made the necessary connections, checked my swr, and tuned up the amp.
Everything seemed to be going smoothly. I loaded the amp up to about 800 watts, and called CQ. During the resulting QSO, I was admiring the beautiful glow, that only four 572B tubes can provide. However, the four tube plates were also a bright cherry red color. I quickly blew off the QSO, and stopped sending CW. The tube plates stayed cherry red. I turned off the rig, put the amp in standby, and disconnected the tranceiver RF from the amp. Keying the amp relay again produced the cherry red plate glow,
with no input drive, and no amplifier output power. The amp did not appear to be self-oscillating, so tube bias point plate current should not provide enough dissipation to produce cherry red plates
I decided that the tubes must be bad. A phone call to Ameritron, resulted in 4 new tubes being delivered to me. I put in the new tubes, and fired up the amp. Again, cherry red plates with no exciter drive. Then, one of the new tubes shorted, and blew out a power transistor, inside the amp. I called Ameritron, who suggested I return the amp for repair. Whatever the shipping was(about $75.00), on an amplifier this size, it was quite difficult for me to pay. Especially since the amp had arrived essentially DOA. I informed Ameritron of the tube shorts, and the Cherry red plates, and told them to check for that.
I waited for the repairs. when I received the "repaired" amp back from Ameritron. I fired it up. Guess what. Cherry red plates again. While I was admiring the cherry red glow, one of the tubes shorted, internally, and blew out the same power transistor again, inside the amp. I went to the electronics store, bought a new transistor, and installed it. The result, was the return of the cherry red plate color again. I reached to turn the amp off, but before I could, I saw another tube short, and the back of the amp seemed to "explode" loudly. A call to Ameritron revealed that, during the repair, my amp had been modified to blow up ceramic disk capacitors, wired into the back of the amplifier, when a tube shorted, instead of blowing transistors etc. I was happy to trade exploding capacitors for exploding transisors. I went to the store, and bought some replacemant disk ceramic capacitors.
I ordered 4 new tubes (paid for all of them this time, because Ameritron had checked the original tubes, and they were "fine"), plugged them in, fired up the amp, saw another tube short, and the capacitors "blew up" again.
I removed the tube that had shorted, replaced it with one of the original tubes, checked OK by Ameritron during the factory repair, headed for the electronics store, and bought 16 more disk ceramic caps. I installed some new caps in the back of the amp, fired it up, observed the pretty cherry red tubes, and heard the "protection capacitors" explode again. I went through the "see the tubes short," "explode the caps","put in new caps", "watch the cherry red plates", "see the tubes short", routine about 5 more times, with no luck at all.
Another call to Ameritron resulted in the suggestion that I return the amp for repair, at about another $75.00 for shipping. At this point I realized that the grid bias was all wrong, on the 572B tubes. It was acting like the tubes were biased Class A, instead of Class AB2, and it had always been that way, on this amp.
I now had a new dead amp, that was going to cost me well over $100.00 total shipping costs to get it fixed, and I had no confidence any more, that Ameritron would actually check, to see if the amp worked, before they shipped it back to me again.
I also received a new AL-800, not fully assembled, with serious persisting problems. That story has a happier ending. I finished assembling it, and then repaired the amp myself. That write up will come later.
Perhaps the new AL572 and AL800 amps are more reliable, and the quality control is better. However, I don't think I care to pay more money for a third bite of the Ameritron amplifier apple, it has been a bitter one, for me.
I do have a Antenna analyzer, a MFJ-4225MV power supply, a MFJ-4035MV power supply, and an Ameritron QSK-5 QSK switch,
that are working just fine.
I finally purchased a Command Technology HF2500. It worked right out of the box, and is still going strong.
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