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1-10 of 13 messages
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AL-811H Help
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by N2WFK on October 30, 2009
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Hello To All,
I just recently purchased from a fellow ham a Ameritron Al-811H amplifier. First off they packed the tubes terribly and and to clean the amp out and purchase two new tubes. When i go and try to tune this amplifier with my Kenwood TS-950SD and from the manual as it states when i turn it on i should see 1700ma and them flipping the switch from HV to ip i should see the needle go to Zero.
Well mine doesnt. It will dance around sometimes getting close to zero. Everyonce in awhile it will stop at zero others it will around alittle higher than that. I did notice that once of the tubes didnt seem to fit all that solid into the seat in the amp. After playing with it alittle seemed to behave alittle better so im not sure if its the tubes since it was packed so poorly or the tube socket?
Also the Kenwood puts out 150W and im showing 500W output through my Palstar tuner with almost no drive? This cant be possible or could it? Must be doing something wrong.
Any Help would be great or if local in the South Jersey / Philly Area....Would be AWESOME....
THANKS
Chris
N2WFK
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RE: AL-811H Help
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by KA5N on October 30, 2009
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First it is 1700 volts and zero current. If the current is not zero with the amp unkeyed then there is something wrong with the cutoff bias.
Second 150 watts is way too much drive. You are going to wreck your tubes if you put this much drive into this amp.
Third sure there could be a problem with the socket. Who knows what abuse the rig suffered in shipping. It is fairly easy to thighten up the clips on the socket.
I would turn off and disconnect the AC cord and throughly look over the entire rig for signs of damage. Often shipped items will be badly vibrated and parts will break. Next get some local help from someone familar with amps to get this amp back in running gear.
Allen
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RE: AL-811H Help
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by WB2WIK on October 30, 2009
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500W output would be about right with maybe 40W of drive or so.
Is that what you're driving it with?
Did you connect the ALC line (this helps a lot)?
The plate current meter "jumping around" during STANDBY (when you're not transmitting) is not right. It should be at "zero," and stay there. If the meter is jumping around, there may be a problem with one or more of the tubes.
When you indicate 500W output power, what does the Ip (plate current) actually indicate?
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RE: AL-811H Help
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by N2WFK on October 30, 2009
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Hello steve,
No i didnt connect an ALC line as i didnt think id need to as im using a Heil FS2 to key this. Will i still need the ALC line between the radio and amp? In the begining of the tunning process the manual states..."With the exciter still at NO drive to place the HV-IP switch to the IP position and on the 750ma scale i should see it read ZERO. But mine doesnt do that right away. Not all the time i should say. Sometimes it dances around ....Sometimes it will get close to zero but not to zero. Then sometimes after alittle more time ......Zero?
Then in the manual it states To key the exciter with NO drive with the Standby OPR switch in the OPR position and i should see the XMT red led light. I do. And i should see the plate current on the 750ma scale read 125ma....well i read 150ma. But they say it can vary by 25%.
Now im not running 150W into this amp as the other gentleman thought i was but it seems weird that im almost putting in NO drive to get 500W out. Im in just not tunning this right. My palstar tuner is correct so i know its not that. I have noticed that one of the tubes doesnt seem to sit as suggly as the others. I dont know if all this BS could be this that some of the tubes are no good or the tube socket is good or what. The tube socket part is so cheap and to send it to Ameritron for 3 weeks to replace that with shipping costs seem unrealistic.
What do you think? If you like you can email me directly im good in QRZ.com. THANKS
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RE: AL-811H Help
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by AD5X on October 31, 2009
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Is your mic plugged into the radio? If you are keying everything and the mic is plugged in, I wouldn't be surprised if ambient noise is causing the "dancing around" in your plate current readings.
Phil - AD5X
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RE: AL-811H Help
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by W8JI on October 31, 2009
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Maybe the meter movement got beat up when the tubes bounced around inside the amp and now sticks ?
The other suggestions are all good also.
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RE: AL-811H Help
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by K1BXI on October 31, 2009
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Would a dirty relay in standby cause the cut off bias to fluctuate enough to allow a little plate current to show on the Ip meter?
John
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RE: AL-811H Help
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by 5R8GQ on October 31, 2009
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All of the above....but first get that tuner out of the lineup and substitute it for now with a dummy load. Solve the amp problems first.
Rig->Amplifier->PWR Meter/SWR Bridge->Dummy Load.
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