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Author Topic: 811 maybe popped and has wierd reading??  (Read 1498 times)
VE7REN
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« on: November 21, 2009, 12:53:50 PM »

ok,. i hooked up the drake mn2000 tuner in line. i was checking my swr/tuner settings on 75/80,when i was turning the load and plate control on the amp. i thought,........at least i think so,that i heard a slight pop come from the amps right side!!

 now the amp seems to get not as vast or variable readings on the meters when i turn the load control?

 it seems to get the same power output on the tuner meter,but the amp just seems to be showing less on the plate current meter,regardless of where i turn the load dial. did i blow something?

 i took the lid off and looked things over good..nothin. no burnt smell or obvious signs,although one 811 tube nearest the outside cabinet looked pretty mirrored or chrome looking,so i changed it out for another used 811 tube in good shape.im thinking a diode or ?? otherwise the amp seems to be working the same.

 im kinda new to this amp stuff.....any ideas.
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W8JI
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« Reply #1 on: November 21, 2009, 03:32:48 PM »

ok,. i hooked up the drake mn2000 tuner in line. i was checking my swr/tuner settings on 75/80,when i was turning the load and plate control on the amp. i thought,........at least i think so,that i heard a slight pop come from the amps right side!!

 now the amp seems to get not as vast or variable readings on the meters when i turn the load control?

 it seems to get the same power output on the tuner meter,but the amp just seems to be showing less on the plate current meter,regardless of where i turn the load dial. did i blow something?

Look on the circuit board near the electrolytic capacitors. There is a fat little single black diode by a small disc capacitor. You blew that diode out when the tube overheated and started to melt.

Any silicon rectifier diode will work, but the original was a 3 amp rated.
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VE7REN
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« Reply #2 on: November 22, 2009, 06:00:10 AM »

i found that my wafer switch in the back for bandswiching has broken also.1/2 of the copper ring has broken and fallen off.

i dont feel comfortable doing the repair. is there anyone in the pacific northwest who is capable or willing to work on this??
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K7ZRZ
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« Reply #3 on: November 22, 2009, 10:47:51 AM »

VE7REN (Name?),

I just sent this thread off to my very good friend Jeff K7ZSA, who is located just south of Bellingham, works in Mount Vernon as the service manager of Dimensional Communications, and is a VERY GOOD TECH. Perhaps he will be interested in making the repair for you.

Brian K7ZRZ
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Brian K7ZRZ
VE7REN
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« Reply #4 on: November 22, 2009, 12:08:30 PM »

thanks brian.

i found that the wafer switch on the back of the amp on the circuit board has broke in half. i dont feel comfy with the repair.
this is all fairly new to me{ amp stuff}.

brent ve7ren
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K7ZRZ
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« Reply #5 on: November 23, 2009, 12:26:42 PM »

Hi, Brent,

I'm sorry to say that the fellow, Jeff K7ZSA, that I mentioned above, is unwilling to perform such a repair for you. He says he has enough projects going on his own, and is also wary of the liability issue of him doing that kind of work. I understand how he feels in this, and am sorry I mentioned him before asking him first about it.

Good luck with the project. I can tell you that with a little fortitude (not that in a bottle Smiley, and the use of a digital camera and good note taking, I'm sure you could replace a switch wafer just fine. Think about it.

Regards,  Brian K7ZRZ
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Brian K7ZRZ
W8JI
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« Reply #6 on: November 23, 2009, 01:22:11 PM »

thanks brian.

i found that the wafer switch on the back of the amp on the circuit board has broke in half. i dont feel comfy with the repair.
this is all fairly new to me{ amp stuff}.

brent ve7ren

Brent,

You mean the blue color wafer in the tuned input board?

Tom
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VE7REN
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« Reply #7 on: November 23, 2009, 08:05:08 PM »

the blue wafer switch.
correct.
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W8JI
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« Reply #8 on: November 24, 2009, 04:53:18 AM »

the blue wafer switch.
correct.

The best way to change that is to get a sharp pair of small cutters with the longest nose you can and cut the switch tabs off. Then you can unsolder the tabs one at a time and remove them and clean the holes out. It isn't hard to change if you can find someone who has done it before.
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VE7REN
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« Reply #9 on: November 24, 2009, 04:12:07 PM »

i would assume, it would be a good idea to take the back panel of the amp off,then work on it.im unsure how i would line up the new wafer switch to corespond with the band switch  # or is there a trick??.
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AE5JU
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Posts: 244




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« Reply #10 on: November 24, 2009, 05:14:27 PM »

Was reading in another thread I can't find now, that other than tubes, the high maintenance parts are a diode and certain caps.

Are they talking about D16 - 1N4007, and, on the AL-811H, the caps C32-36  - .01 uf 1kv?
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