Need the Ameritron ALS-500 Export Amp Diagram

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Unit 67
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Need the Ameritron ALS-500 Export Amp Diagram

Post by Unit 67 » Monday 22nd Sep 2008, 7:09

Hi at everyboby;I need the Ameritron ALS-500 Export type amplifier schematic.It is because i got one but this amp not have the 10 meters frequency modification.I got a lot of different types of Amateur Amplifier schematics and a lot of info about Amateur Amps modifications,but not for the ALS-500 amplifier and Many Thanks Anticipated!!!!


Psssssss;I did the search in the mods.dk with no results.

timrim
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Post by timrim » Monday 22nd Sep 2008, 8:03

Normally all you would need to do is re-tap the tank circuit coil for 11 meters, the higher in frequency you go, the shorter the coil will need to be, this does take some experimentation. If you know the values of the plate and load caps, you could calculate the inductance needed and just tune the coil on a LCR meter.

If the amp already has a 10 meter position, you should only need to move the tap over a turn or two.

Unit 67
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Post by Unit 67 » Monday 22nd Sep 2008, 11:36

The amp has 4 2SC2879 final transistors and the input network of this amp is electronically controlled.Tomorrow i am going to make a direct jump between the Aux position and the first stage of the Pi-network for test if the SWR is OK.The input circuit of this amp looks exactly of the 15,20,40 Meters input network of the Palomar TX-100 amplifier.I am talking about the multiband kit of the Palomar TX-100,because the Palomar TX-100 specifications covers the 15,20,40 and the 75 Mhz. Freq,but there is a Palomar kit for this purpose and is for mounted in the back of the Palomar TX-100 amp.The input network band circuit of the Ameritron ALS-500 is very similar!!!!!!!!!

Unit 67
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Post by Unit 67 » Thursday 25th Sep 2008, 10:29

Go it!!!!

Here is the mod for the ALS-500 Ameritron amplifier without the MOD-10M kit."The kit cost $29.95 plus S&H"

1.With the front of the amplifier facing to you in the left front side you have to locate 4 little towers.
Note:The first and the third tower are grounded together via the chassis

2.Make a jump between the second and the fourth tower and thats it.I use a piece of #14 gauge cable for this purpose.

Now you can work in the 10 Meters in the "Aux" position.

I noticed a problem with the amplifier in the AM mode because the "Thermal Protection circuit" lights on at very low temperture,but you can adjust the R248 pot for your desired preference settings and here is the results with a Cobra 139XLR.

With 7 watts RMS and 35 watts PEP i got 120 watts RMS with 300 watts PEP in my Bird meter.We have to remember that this amp came from the factory to work with a high output driver radio."About 35 to 60 watts RMS" and the input SWR of the amplifier is perfect.About 1.1 to 1.4 SWR across the entire frequency.

Note:
This is with my Ameritron 2KW dummy load because is prohibited by Law to use this amp outside of the Amateur bands and in the 11 meter frequency!!!!!!!

Pssssss;For the cost this amp has a very poor electronics and mechanical construction.

timrim
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Post by timrim » Thursday 25th Sep 2008, 11:07

Glad you got it working, apparently I read your original post too quickly and somehow got the idea that it was a tube amp....sorry!

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