[Amps] AL 80B Question

[Steve Katz]

I have a newer AL-80B and just for giggles have tried it on 30m into a dummy load.  It does just as you report.  I re-tuned the 20m input coil to drive it much harder on 30m and sure enough, it loads up much better that way, with the LOAD control close to mid-range and >500W output.

But then the input VSWR on 20m is poor, so I re-set it per the factory settings and gave up thinking about using the amp on 30m.  It's only 3 dB over my barefoot transceivers anyway!

WB2WIK/6
 
 
 
In a message dated 1/19/2009 3:50:45 P.M. Central Standard Time,  
w2wg at comcast.net writes:

I have a  very early AL80B.  It will produce 500-700W key down on  all
bands--except 30m.  Of course you don't need much of an amp on 30m  with the
limit being 200W, but I am  curious as to what the problem  is.  The
suggested Ameritron tuning chart shows the load control at 0,  which is
presumably plates fully meshed.  That indeed is where it  wants to be loaded
on 30m, but it struggles to  put out 150w,  regardless of how hard you drive
it.  Neither plate current or grid  current is excessive.  The amp has a
30m/20m selection on the  bandswitch and I get 700W out on 20m.  What would
the problem likely  be.  Has anyone else run into this on 30m?  I bought this
amp  used around 1995 and it has always had this behavior.

Bob W2WG