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Author Topic: AL80B Low output on 160 meters  (Read 445 times)
N4PYI
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Posts: 2




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« on: October 22, 2008, 03:05:56 PM »

I am having a problem with my ameritron AL-80B amplifier not making full power on 160 Meters. Once the amp has been tuned properly (according to the manual) on 160, it reaches maximum saturation at around 50 watts drive. At that point the plate and grid current begin to go up but the output power does not increase above about 650 - 700 watts. All other bands with the exception of ten meters obtain full power with low grid current. Ten meters behaves much like 160. Anybody seen this movie? A call to Ameritron Tech support did not avail much help.
Thanks!
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WW5AA
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Posts: 2088




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« Reply #1 on: October 23, 2008, 07:03:29 AM »

It sounds like an antenna or maybe a tuner problem. Is the radio cutting back any when not tuning? Just a guess, I had this happen with the auto tuner and a highly reactive loaded inverted "L" I was playing with at one time. The tuner would find a 1:1 at low power but with high power the SWR would slightly change and cause the radio to cut back just enough to lower the amps output.

73 de Lindy

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N4PYI
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Posts: 2




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« Reply #2 on: October 23, 2008, 11:27:39 AM »

Thanks...not using an auto tuner between the radio and the amp. Also it behaves the same way loaded into a 1KW dummy load.
73 de N4PYI
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K8KAS
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Posts: 569




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« Reply #3 on: October 29, 2008, 09:39:56 AM »

Sounds like you are not LOADING the amplifier properly, sometimes the fixed load padding caps change value on 160 meters. Can you get a peak in output as you vary the loading control or is the knob full ccw or cw?

160 meters can be touchy feely, this can be effected by the antenna load values and how it effects the loading cap values. You might have to add an additional 500 pf to the output side of the pi network. Is it worth it for 200 or 300 watts additional power out??? Denny K8KAS
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