ALS600 Thermal Shutdown

[VA3PUX]

For those who own an Ameritron ALS600 have you ever had it thermally shutdown on you and if so how hard were you driving it from a time point of view?

[WX7G]

Mine has never shut down our exhausted more than luke warm air when running CW.

[N5TEN]

It will shut down on you if your power supply isn't well ventilated. Also, if you have the switching PS and your amp is a few years old, the 12v regulator could be ready to fail, is this happens a lot. Ameritron also says it's possible the circuit could be hampered by other devices on your 120v line which could cause this, and lastly, a final can be going out if it happens a lot. Start by checking the ventilation on amp/ps, fans, and look at other cooling options like an exhaust fan near the vents to help it exhaust the hot air.

[VA3PUX]

Sent the amplifier to Ameritron and they indicated that the repair centre that replaced the finals had the bias way out of adjustment.

Amplifier is on its way back home soon and will report the new results.

[N5TEN]

Sent the amplifier to Ameritron and they indicated that the repair centre that replaced the finals had the bias way out of adjustment.

Amplifier is on its way back home soon and will report the new results.

What did they charge you? Mine is on the way back to them as well.

[VA3PUX]

No charge since it is under warranty. The shop that did the repair paid for shipping to Ameritron. I have had the amplifier since Feb. of this year and it has spent more time in the shop then on my desk. Also have a MFJ 998 tuner on it's way back for a repair. I baby my gear and will never buy MFJ products again.

[N5TEN]

I have the same tuner for my als-600 and it's never given me any problems. Do you have the latest software update in that tuner? When I bought mine from AES, it was immediately defective right out of the box. I shipped it to MFJ and they just sent me another, newer one with the updates. In my experience, AES has in the past, sent me old new stuff. Anyway...the new one has been fine.

[VA3PUX]

The latest firmware has been installed for some time. It is now at MFJ for repair and I will be selling it once it gets back.

The LDG AT-1000ProII tuner has been working great.

Got the amplifier back and it seems to be working fine.

[WX7G]

I have not had any trouble with my ALS-600. However, when I sold my ALS-1200 a bias pot adjustment rotated during shipping. When I got it back I adjusted the pots. I suspect this is a problem that MFJ is not aware of otherwise they would anchor the pot adjustments with a drop of adhesive.

[K0BG]

I've owned two ALS-600s. Both were from an estate, and both had fried finals. Knowing the owner, and his operating style, I wasn't surprised. The 600 requires just about 60 watts of drive, and if you drive them harder the input resistor bank get hot. Over time, the resistors increase in value, which overdrives the finals, and they fail. With proper drive, and the use of ALC, they're about as solid as any amp.

Having owned those two (one with the switching PS, and the other an analog), I'd say the switcher is a better overall setup. Sure makes a lot less noise.