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Ameritron AL811 / AL811H

SharpShooter

SharpShooter

Member
Apr 11, 2010
58
1
16
How would this amp work out for me ?


I'm thinking of using the 811 or 811H with my dual final export radio. ( Superstar 158EDX )

Radio Dead-Keys 15 watts and swings 50 watts.

What wattage should I expect using SSB ?

What wattage should I expect using A.M. ?

Would this amp work using A.M. ? ( the information provided by AES doesn't list A.M. )
http://www.aesham.com/display_pages/al811.shtml


I've read a few posts that talk of needing a " PTT switch "

or needing a " Keying Switch ?"

Would I be needing either of the " switches "



Or need anything else ?



The reason I am interested in using a HAM amp instead of a CB amp.... is it will be useful as I move up in the HAM hobby.



Thanks.
 
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I would think that your radio will drive either of those amplifiers. Maybe not to full output, depending on the mode, but still drive them. As for keying the things, neither do 'RF switching' so a means of keying them is a good idea.
- 'Doc
 
yes you would need a way to set up an exciter to excite (key) the amplifier it can be done you would be better off using a Texas Star 400 or 500 and a 52 amp or larger supply. Those to amps would be great for what you want to do and work great on 10-12 meters Ive tested them I own a few dont drive them hard and they are pretty clean.
 
The reason I am interested in using a HAM amp instead of a CB amp.... is it will be useful as I move up in the HAM hobby.
Click to expand...

Well, you've got the right idea there. The tests aren't that difficult...if buying this amp gives you the incentive you need to start "moving up" (as you put it), then by all means do it.

Here is an older post that covers this amp pretty well:

http://www.worldwidedx.com/amplifiers/26295-ameritron-al-811-h.html
 
The easiest way to key the amp would be a Radio Shack foot pedal or any type of momentary contact switch. The amp will have an RCA jack on the back for keying it. Grounding the center pin will engage the transmit relay. Neither of those amplifiers will work on 10 or 11 meters out of the box. They require cutting one green wire inside of the amplifier to enable operation on these frequencies.

Since your radio will not make enough power to fully drive the amp, it makes little sense to buy the fourth tube with that radio in mind. With the drive you have available you can expect about 100 watts carrier and the PEP "swing" should be around 400 watts (slightly more on SSB). You may be able to turn the drive up on your radio to produce a little more dead key but you should not set it beyond 25% of the maximum PEP swing. Your current radio will under drive the amp by less then 3db and that's hardly even noticeable.

The Ameritron is a much better choice of amplifier in terms of signal purity and future use on other HF bands then the Texas Star would be. While there are many 11 meter solid state amps that are worse then the Texas Star, you simply can't compare a transistor amp with no harmonic filtering to the Ameritron in the area of spectral purity (running clean).
 
Shockwave said:
The easiest way to key the amp would be a Radio Shack foot pedal or any type of momentary contact switch. The amp will have an RCA jack on the back for keying it. Grounding the center pin will engage the transmit relay.
Click to expand...



In other words....all I would be doing is creating a dead short across the RCA jack ?


So a 2-wire RCA cable and a simple on-off type of switch is all that I would need ?

Flip of the switch would activate the 811.



.
 
Yes, that is correct but the idea is to use a switch that is convenient to operate like a momentary switch that automatically returns to off. Otherwise you could just short the RCA jack and use the standby / operate switch on the front of the unit. Keep in mind you will have to activate the switch every time you change between receive and transmit using the amplifier.
 
Sonwatcher said:
I believe you will have to key the amp before you engage transmit on the radio. That is what I was told.
Click to expand...

Being that the amplifier does not have a vacuum relay, that is good advice to prevent hot switching. This will extend the relay life inside the amplifier. At the same time you should "unkey" the amp after the radio for the same reason.
 
You can use a guitar foot peddle and solder an RCA jack on the end in place of the phono jack. I also made one with a toggle switch on one end.
 
SharpShooter said:
Does anyone make a pre-made cable/switch ?

I searched AES HAM and didn't find anything.
Click to expand...

Not that I'm aware of because the radios they were designed to work with would normally be providing the transmit key line. Amateur transceivers have a jack on them that mates with the RCA on the Ameritron to provide this function. In the absence of this type of radio, most prefer to use a foot activated switch. Radio Shack sells one but it has a mini 1/8 inch plug on it as I recall. You would have to replace the plug with an RCA to match the amp or buy an adaptor from the Shack too.
 

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