AL-800 ALC Adjustment Has No Effect

[Sandlapper]

I have a new-out-of-the-box AL-800 that I powered up for the first time 2 days ago (9/16/2022). I intend to run it at 450 Watts output CW (in order to have plenty of current margin under the 15A house circuit I'm using). I'm driving the amplifier with 40W from my FT-840, and I get 450W out into a dummy load (after slightly over-coupling the LOAD, and both grid and plate current readings are well within maximums).

I'm using an Ameritron ARB-704 interface through a PNP-8M Cable. No problems triggering the T/R relay. However, transmitting as described above, the ALC adjustment has no effect, from stop-to-stop.

I suspect this is so because the drive power (40W) is too low to trigger the ALC signal from the AMP to the transceiver.

I'm checking other places, including Ameritron, to understand why I'm getting this result, but welcome other input. Thanks.

 

[nomadradio]

The intended reason to have ALC is to keep an amplifier's drive level below the "flat top" point, where modulation peaks get chopped off by the amplifier's upper power limit.

Does sound as if your drive level just isn't enough to trip the amplifier's ALC detector.

73

 

[BJ radionut]

https://static.dxengineering.com/global/images/instructions/ame-pnp-8m.pdf

See instruction #2...do you have the ALC cable going to the amp in the proper ALC feedback jack?

 

[Sandlapper]

The intended reason to have ALC is to keep an amplifier's drive level below the "flat top" point, where modulation peaks get chopped off by the amplifier's upper power limit.

Does sound as if your drive level just isn't enough to trip the amplifier's ALC detector.

73

Thanks, Nomad. Much appreciated. 73

 

[Sandlapper]

https://static.dxengineering.com/global/images/instructions/ame-pnp-8m.pdf

See instruction #2...do you have the ALC cable going to the amp in the proper ALC feedback jack?

Thanks, BJ. Yes, and 3x checked. Plus, there are only 2 RCA jacks on the AMP; one is for the relay signal {which works fine}; the other is for the ALC. But, never hurts to 4x check.