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Author Topic: TUNING THE AL-811  (Read 1786 times)
KB3RMX
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Posts: 14




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« on: October 05, 2007, 01:43:14 PM »

Hi Fellows
I just acquired a AL-811, seems like just about everyone has one of these. I'm new to the amplifier scene and am a little gun shy about how to tune this.  The directions that come with this are very vague.  I am using this on my Icom 756 Pro 3.  I understand that I do not need the interface with this rig like some other rigs need. I don't plan on running at max power.  I just want to use this for ssb about 400 watts output.  I would appreciate very much if any of you out there can give me some pointers before I load this thing up. I also will be using a palstar tuner inline with the amp. The antenna I'm using is a Hustler 6btv.
Thanks - Mike
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N3JBH
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Posts: 2358




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« Reply #1 on: October 05, 2007, 04:17:21 PM »

Hello Mike i have used both the 811 3 tuber and now using the 811-H 4 tube model and and also use a Palstar tuner. now i will let you know the first thing is using the wattmeter on the Palstar tune for max output period.

Now lets discuss grid current first if you running the 3 tube model dont ever exceed 150ma. on the grid.

if your using the 4 tube model dont go over 200 ma.

also set up the ALC if you need help there let us know. Now tune your tuner first for best match. then bring on your amp. first use CW mode for easiest tunning. Adjust your Plate control for max out. then adjust the load for same.

Keep an eye on the grid current. never exceed the grid current we talked about. Now many guys like to turn the load control clockwise a bit more then where the peak is. you will see the grid reduce some aswell.

This is called loading to the heavy side. much better then light loading.   repeat  the plate and load to besure this is good. and your done.

 now a few comments never reduce out put  with amp control's
reduce your  transmitter output to reduce the amps out put.

never over drive the amp it wont make any more power just a bunch of qrm.

and keep all tuning times short as you can.  5 seconds is plenty of time  to set the amp up. if you need more time just unkey and wait a minute or so then retry.

and last dont get excited when you go to SSb mode any your meters dont show  what you assume is high power readings. the amp is working. your meter's just cant read that fast.

and last make a sheet up to show your settings for the bands. this save you much time and save your tubes from needless abuse.

Well i hope i was some tiny bit of help   Jeff N3JBH
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WD8PTB
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Posts: 670




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« Reply #2 on: October 05, 2007, 04:20:27 PM »

I used a 746pro and 756pro III without an interface and had no problems with the 811h, Al80a, and als500m.
  Practice tuning up with low drive. Start with just enough drive to move the plate current a little. Always watch the grid and plate current. Keep them low untill you get the hang of it then use the values in the manual.
  Making sure the plate has been resonated before you apply much drive will help keep the tubes in good shape. If I give you an exact proceedure it is a sur thing that someone will violently disagree. 73 WD8PTB
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W1NK
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« Reply #3 on: October 07, 2007, 06:45:39 PM »

Allow me to add 2 simple words... Dummy Load.  This way you'll keep interference to a minimum.

Everything Jeff said is on the money.  I always tune my AL-811 into a dummy load (Palstar), then briefly tweak it when I switch to my antenna(s).  With "heavy" loading, I find I can get about 450-500W out with the grid current right around 100mA.

Frank, W1NK
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KB3RMX
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« Reply #4 on: October 08, 2007, 07:10:35 AM »

Thanks Guys. I forgot to mention that the amp I have is used.  I may have to check this thng out before I hook it up. Original owner says its working great.  I'm a little bit confused about the ALC setting.  The ALC input for the 756 pro 3 requires 0 to -4 volts - I'm not sure if the ALC pot has to be adjusted on the 811 or not to suit my radio.  I want to make sure that this thing is working and set right.  My 756p3 is brand new and I don't want to blow it up! Like I said before I'm very new to this amplifier thing and the instructions Ameritron gives you are very very vague.  Mike
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N3JBH
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« Reply #5 on: October 08, 2007, 10:49:09 AM »

The Pot on the back of the Amp will need adjusted. you will no blow your radio up dont worry about that. if your amp is sending to much ALC signal to your radio it simply wont put out a signal.

What i have done was load and tune the amp using the maxium rated input for your amp. 55 watts (3 tube) 70 watts(4 tube) then adjust the pot on the rear of the amp till you just see your radio's out put starting to cut back. now turn you pot back up  till you just stop seeing any drop in your out put on the transmitter. at that point you safely adjusted your alc setting.

Please use a dummy load while doing this. and i recomend you make this adjustment on the 40 meter band.  it seem's at least on mine the 40 meter band has to most gain so there for i choose it to make adjustments.

Agian hope that helps some.

Oh and use fairly good sheilded cables for your hook up's. i dont mean get sucked into the monster mega supper dupper  1 million percent oxygen free wonder cable stuff. thats simply hog wash. just good  A/V type cables.
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KB3RMX
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« Reply #6 on: October 08, 2007, 11:01:15 AM »

Thanks Jeff, You have been very helpful.  I use LMR 400 for all of my radios HF to UHF even my 900 radio, Its great coax.  Hope to catch You on 40 meters.
Thanks again - Mike
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N3JBH
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Posts: 2358




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« Reply #7 on: October 08, 2007, 11:05:27 AM »

your most welcome Smiley
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