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Author Topic: Ameritron AL-80B Hi input SWR on 40 meters  (Read 1177 times)
KD0GES
Member

Posts: 28




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« on: April 03, 2013, 12:53:43 PM »

I have an AL-80B amplifier that has a high input SWR on 40 meters of three to one and I can only get 500 watts into a dummy load.
I have adjusted the tuned input slug and the SWR only goes down to 3 to 1.
I have cleaned the band switches and the dummy load has tested good with a another amplifier.
I get 800 to 1000 watts on all other bands.
Any ideas to fix it?
Thanks
Dale (KD0GES)
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W1QJ
Member

Posts: 1439




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« Reply #1 on: April 03, 2013, 01:04:45 PM »

perhaps one of the mica caps on the input coils to ground crapped out
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AD4U
Member

Posts: 2152




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« Reply #2 on: April 03, 2013, 03:37:12 PM »

Also look for poor soldering in and around the 40M input circuit.  Amertron (MFJ) is famous for poor soldering.

Dick  AD4U
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K5RT
Member

Posts: 123




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« Reply #3 on: April 04, 2013, 05:08:22 AM »

Lets start from the top.
Is the amp new and this is an "put of the box" finding?
If so, many things could be the cause. Confirm the tap on the plate coil is in the correct location, or as previously noted, check solder connections. Confirm the values of the tuned input circuit components are correct. Contact Ameritron as well
If the amp worked on 40 meters previously, check to make sure your radio isn't the culprit. Turn off the internal antenna tuner. If you've ruled out cockpit troubles, check from a broken connection or burned component.
Let us know what you find out
Vy 73
Paul
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K4RVN
Member

Posts: 758




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« Reply #4 on: April 07, 2013, 10:29:43 AM »

I would suggest trying the transceiver into the dummy load barefoot, no amp. Will it load 100 watts or full output and what does the SWR indicate on the transceiver alone?
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