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Author Topic: 10M mod for AL-811H  (Read 4266 times)
W3MKT
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Posts: 13




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« on: March 25, 2011, 02:50:03 PM »

I purchase a new Al-811H amp in December when I was back in the U.S. and brought it back to El Salvador. Now that I have used it a while I would like to get it working on 12M & 10M. I e-mailed Ameritron requesting the mod. and attached the copies of my licenses but did not get a response. I'd appreciate if some one could e-mail me the mod. I found references to the mod by doing a Google search and on QRZ.com it was mentioned to cut the green wire going over the metal divider. The only green wires in my amp are 2 green wires attached to the bandswitch circuitboard. I'd appreciate any help I could get.
73 de Gary YS1GR (W3MKT)
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W1QJ
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Posts: 1486




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« Reply #1 on: March 25, 2011, 03:07:38 PM »

Gary, open the amp up and look in the back where the tuned input coils are.  There should be a green wire on the 10m coil that is grounded.  Snip it and 10 m will come alive.  Lou
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KM5PS
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Posts: 86


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« Reply #2 on: March 26, 2011, 06:06:37 PM »

Gary- Did you get your AL811h working on 10 mtrs?  I am trying to get mine also to work for 10 mtrs. I cut the wire that was mentioned and still not working here.  I may need to tune the coil first before it will work.  I have to borrow the right size of hex wrench from a friend first.  For anyone who can help I have a link below showing the wire that I cut.  Is this the right wire?   I am getting 460mA on plate current and abt 60 mA on Grid current with 30 watts of drive.  When I tune the amp there is no change in readings.  Any help would be great..

John
km5ps
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KM5PS
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« Reply #3 on: March 26, 2011, 06:18:07 PM »

Sorry forgot to add the link:  http://km5ps.com/AL811H  and look at the 10 mtr mod picture..
John
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K7KBN
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Posts: 2825




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« Reply #4 on: March 26, 2011, 09:00:07 PM »

That should be a 0.1 inch hex in the slug, but don't use a metallic tool!
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73
Pat K7KBN
CWO4 USNR Ret.
N3OX
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« Reply #5 on: March 27, 2011, 07:16:08 AM »

For anyone who can help I have a link below showing the wire that I cut.  Is this the right wire? 

Looks like it.

Quote
I may need to tune the coil first before it will work. 

What's the SWR seen by the exciter when you're trying to tune up?

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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
KM5PS
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Posts: 86


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« Reply #6 on: March 27, 2011, 07:33:55 AM »

The swr on K3 readout is 1.6-1.  Does the coil need to be adjusted before the amp will show power out?  I thought that it should be showing something even if the swr adjustment in the coil might be off some.  Thanks again

John
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N3OX
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« Reply #7 on: March 27, 2011, 07:56:26 AM »

The swr on K3 readout is 1.6-1.  Does the coil need to be adjusted before the amp will show power out?

There was no need for that on my AL-811, and if you're getting 1.6:1 I think it's probably properly adjusted.  You have to compromise between 12m and 10m so the network is preset to be as low as possible on both bands, but on my AL-811 that's not very low... 1.6:1 sounds fine (others can chime in too).  In my case, I didn't have any output on 12 or 10 and a really high input SWR.  Then I clipped the wire and 12 and 10 worked fine on the AUX position, no other issues.  I bought a tuning tool but I only needed that to adjust the 15/17 network (which I think was maybe adjusted by the ham I got the amp from who was actually using it to drive the dees in a cyclotron, not actually using it on the ham bands)

I wonder if it's possible that Ameritron changed the modification to make it a bit more complicated?   You might want to actually contact them and get all the details, pointing out that you have a yellow wire, etc.
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
KM5PS
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Posts: 86


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« Reply #8 on: March 27, 2011, 08:32:48 AM »

Alright thanks,  That is what I thought about doing-contacting Ameritron.  Thanks for the help..

John
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KM5PS
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« Reply #9 on: March 27, 2011, 09:42:48 AM »

Dan- I think I misinterpreted your response on the swr reading.  The reading I gave you was bypassing the amp, but when I engage the amp the swr 5.0.1.  So I think that I need to adjust the coil before i will see any power increase in the meters.  A friend on mine has a plastic .1 inch hex tool for me to use.  So when I get it from him, I will try tuning the coil then.  Not much on 10 mtrs right now anyway.  HI HI..  Thanks again for the information..

John
km5ps
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N4ATS
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Posts: 845




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« Reply #10 on: March 27, 2011, 01:57:58 PM »

Google it , it is all over the place!
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N3OX
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« Reply #11 on: March 27, 2011, 03:26:22 PM »

Dan- I think I misinterpreted your response on the swr reading.  The reading I gave you was bypassing the amp, but when I engage the amp the swr 5.0.1.  So I think that I need to adjust the coil before i will see any power increase in the meters. 

Oh ok, yes maybe the slug is your problem.
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
KM5PS
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Posts: 86


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« Reply #12 on: March 27, 2011, 04:35:10 PM »

Got 10 mtrs working on AL 811H.  Just had to tune the 10 mtr coil.  Thanks everyone!!

John
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