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Ameritron AL-811 ALC Question



 
 
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  #1  
Old October 5th 05, 03:46 AM
[email protected]
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Default Ameritron AL-811 ALC Question

I have a question for anyone who owns an Ameritron AL-811 amplifier.

I have connected the Relay and ALC connections to my rig and the
amplifer works great except for the ALC protection. I have confirmed
for 100% certain the radio is connected correctly.

When attempting to adjust the ALC limit on the rear of the amplifier as
suggested in the manual I am not noticing any effect on the rig. I
have driven the amplifier up to to 85W, and still do not notice and
reduction of power on the radio as indicated in the manual.

Perhaps I am missing something, but my understanding was when the power
into the Amp was over 70W and the rear ALC control was adjusted the
voltage from the Amp should kick in and power down the radio to avoid
distortion.

Any assistance would be greatly appreciated. Even if someone knows
which is MAX and MIN on the back panel ALC adj., that would be helpful
(i.e. clockwise or counter clockwise).

Thank-you...

Lloyd


  #2  
Old October 5th 05, 04:27 AM
Rick Frazier
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I think you may be a bit confused about ALC, or I don't understand your
terminology.
In my world, "power down the radio" means it would be turned off.

ALC, when properly adjusted, is a control voltage that should limit the
power output of the transceiver to prevent overdriving and damaging the
amplifier. For Amplifiers that have relatively low drive needs for full
output, it can be helpful in extending the life of the tubes, as compared
to the reduced life effect of driving them beyond their dissipation rating.

I used to have an ameritron 811H (four tube version) and no longer have the
manual, but if I remember correctly, the setting method was to transmit a
known signal level into the amplifier and adjust the ALC control on the amp
until the power output of the amplifier dropped (just barely), thus setting
the level for protection. After it was properly set, cranking up the power
output on the transceiver had little effect when the amplifier was not in
standby mode.

A caveat though: Even though implementing ALC is a relatively good idea,
it is generally better to have really good operating habits and watch the
levels, rather than relying on the Amp to protect itself. I know there is
always the possibility of making a bonehead move (I'm sure we've all made
one now and then) but good operating habits first are the best defense
against overdriving an amplifier.

Thanks
--Rick AH7H

wrote:

I have a question for anyone who owns an Ameritron AL-811 amplifier.

I have connected the Relay and ALC connections to my rig and the
amplifer works great except for the ALC protection. I have confirmed
for 100% certain the radio is connected correctly.

When attempting to adjust the ALC limit on the rear of the amplifier as
suggested in the manual I am not noticing any effect on the rig. I
have driven the amplifier up to to 85W, and still do not notice and
reduction of power on the radio as indicated in the manual.

Perhaps I am missing something, but my understanding was when the power
into the Amp was over 70W and the rear ALC control was adjusted the
voltage from the Amp should kick in and power down the radio to avoid
distortion.

Any assistance would be greatly appreciated. Even if someone knows
which is MAX and MIN on the back panel ALC adj., that would be helpful
(i.e. clockwise or counter clockwise).

Thank-you...

Lloyd


  #3  
Old October 5th 05, 04:53 AM
[email protected]
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Posts: n/a
Default

Hello Rick,

Your assessment matches the manual, however if you have any specifics
on the adjustment that would be helpful. (When I said power down the
radio I did mean decrease the output power on the radio).

Do you need to drive the amplifer with 70W+ or will the ALC control
work with 30W drive from the radio?

I followed that same process, however did not notice the "drop" in
power on the amp or tranceiver when adjusting the ALC adjustment on the
back of the AL-811.

Thank-you
Lloyd

  #4  
Old October 5th 05, 11:19 AM
Amos Keag
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What transceiver are you using? Is the polarity of the ALC voltage
compatible with your transceiver?

I use an AL-80B. It has an ALC range of 0 to -10 vdc. My ICOM has a max
ALC of -4 vdc. I set the AL-80B for -4 vdc at max setting. Then I
adjusted the ALC SET on the front panel to activate at approximately 70
watts of drive.

The point I'm making is that two adjustments were required. First set
MAX ALC voltage, followed by setting ALC SET threshold.

wrote:

Hello Rick,

Your assessment matches the manual, however if you have any specifics
on the adjustment that would be helpful. (When I said power down the
radio I did mean decrease the output power on the radio).

Do you need to drive the amplifer with 70W+ or will the ALC control
work with 30W drive from the radio?

I followed that same process, however did not notice the "drop" in
power on the amp or tranceiver when adjusting the ALC adjustment on the
back of the AL-811.

Thank-you
Lloyd


  #5  
Old October 5th 05, 06:25 PM
[email protected]
Guest
 
Posts: n/a
Default

Thank-you Amos,

I was able to confirm the polarity and connection are correct and the
voltage ranges are compatable between the rig and amp (AL-811).

The manual for the AL-811 is very unclear as to exactly what the
process is to set the ALC control on the back of the Amp:

- What mode should be used on the rig?

- What power level is required on the rig to slightly overdrive the Amp
enough and obtain a neg voltage on the ALC output on the Amp.

- When looking at the back of the AL-811 and the ALC control knob,
which is MIN and which is MAX sensitivity?

My appologies for all the questions. My hopes are to find someone with
an 811 who can describe the process they used.

Lloyd




Amos Keag wrote:
What transceiver are you using? Is the polarity of the ALC voltage
compatible with your transceiver?

I use an AL-80B. It has an ALC range of 0 to -10 vdc. My ICOM has a max
ALC of -4 vdc. I set the AL-80B for -4 vdc at max setting. Then I
adjusted the ALC SET on the front panel to activate at approximately 70
watts of drive.

The point I'm making is that two adjustments were required. First set
MAX ALC voltage, followed by setting ALC SET threshold.

wrote:

Hello Rick,

Your assessment matches the manual, however if you have any specifics
on the adjustment that would be helpful. (When I said power down the
radio I did mean decrease the output power on the radio).

Do you need to drive the amplifer with 70W+ or will the ALC control
work with 30W drive from the radio?

I followed that same process, however did not notice the "drop" in
power on the amp or tranceiver when adjusting the ALC adjustment on the
back of the AL-811.

Thank-you
Lloyd


  #7  
Old October 8th 05, 03:24 PM
Dick, AA5VU
Guest
 
Posts: n/a
Default


When attempting to adjust the ALC limit on the rear of the amplifier as
suggested in the manual I am not noticing any effect on the rig. I
have driven the amplifier up to to 85W, and still do not notice and
reduction of power on the radio as indicated in the manual.


I have an external power meter between my rig and the Ameritron Amplifer
and have noticed the power output of the rig is less with the amp on.
If I follow the normal tune up procedure using about five watts of drive
then increase in increments, I can get the max output at about 45 to 50
watts. I cannot get the rig output more than 55 to 60 watts with the
amp ON. Is this normal?

Dick AA5VU
  #8  
Old October 8th 05, 05:53 PM
Amos Keag
Guest
 
Posts: n/a
Default

Dick, AA5VU wrote:
When attempting to adjust the ALC limit on the rear of the amplifier as
suggested in the manual I am not noticing any effect on the rig. I
have driven the amplifier up to to 85W, and still do not notice and
reduction of power on the radio as indicated in the manual.



I have an external power meter between my rig and the Ameritron Amplifer
and have noticed the power output of the rig is less with the amp on.
If I follow the normal tune up procedure using about five watts of drive
then increase in increments, I can get the max output at about 45 to 50
watts. I cannot get the rig output more than 55 to 60 watts with the
amp ON. Is this normal?

Dick AA5VU


Either your ALC is working or the VSWR is too high! If VSWR is too high
someone may have 'fiddled' with the input tuning to the amplifier.

  #9  
Old October 8th 05, 07:42 PM
Charlie
Guest
 
Posts: n/a
Default

Try it on several bands. It may be the ALC is set a tad too high and it is
limiting the transceivers output just as it should. In which case readjust
the ALC. It may also be bad tuned input tanks and/or a bad tube(s).

My AL-80B had high vswr on 15/17M tuned input b ut the problem was a soft
3-500Z. Fortunately it was covered under warranty. I made a night light out
of the old tube. See here...

1. http://deepsouthnet.net/images/3-500Z-NiteLite.jpg

--

Charlie-AD5TH
www.ad5th.com






"Dick, AA5VU" wrote in message
...

When attempting to adjust the ALC limit on the rear of the amplifier as
suggested in the manual I am not noticing any effect on the rig. I
have driven the amplifier up to to 85W, and still do not notice and
reduction of power on the radio as indicated in the manual.


I have an external power meter between my rig and the Ameritron Amplifer
and have noticed the power output of the rig is less with the amp on.
If I follow the normal tune up procedure using about five watts of drive
then increase in increments, I can get the max output at about 45 to 50
watts. I cannot get the rig output more than 55 to 60 watts with the
amp ON. Is this normal?

Dick AA5VU



 




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