[Amps] Problem with AL-80A

[Scott Manthe]

The AL-80A plate choke was always resonant near 25mHz to discourage CB 
use. And you shouldn't use the MP's internal tuner with the amp. This 
makes it very difficult to properly tune the amp, as the rig's output is 
constantly changing, because the tuner tries to track the changes of the 
impedance inside the amp as you tune.

73,
Scott, N9AA

Kari Lehtimäki wrote:

>Hi all,
>
>Just purchased an old AL-80A and noticed that there is something peculiar going on.
>
>I was running RTTY on 15m (300W out) and the output power started to decrease to 200W after every CQ.
>
>So I went through all the bands from 20 to 10 and noticed the following.
>
>Band drive Ip Pout
>20m 15W 150mA 200W
>17m 20W 220mA 200W
>15m 25W 250mA 200W
>12m 40W 340mA 200W
>10m 15W 200ma 200W
>
>What can you tell me about these figures? Is there a problem here? Has the Plate Rf Choke become resonant close on the 24.5 MHz band for some reason?
>
>My test setup was:
>FT-1000MP (Using the tuner with the amp)
>AL-80A
>R-7 Vertical
>Bird 43 wattmeter (after the Amp. - drive power as indicated by the rig)
>
>73 de Kari, OH2XX
>
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