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Author Topic: Help me Choose an AMP...(My First)  (Read 2455 times)
W1DY
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Posts: 29




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« on: August 07, 2003, 09:43:08 PM »

I will be getting an AMP soon...
And within my price range I'm looking at either a Used Ameritron AL-811H
Or
A Used Ameritron AL-80B

My rig is a FT-990...

I really love Contesting....and contest MUCH more than Rag Chew (RTTY IS MY FAVORITE MODE!!!!)

This will be my first amp...and I have had a lot of success with the 100 watts the FT-990 puts out on it's own.

I'm leaning toward the AL-80B ..But really need some help with this decision...

Help me spend my money!

Wendy
(W1DY)

please feel free to contact me direct on my yahoo e-mail..that way I can read it wherever I may be....(actually it's my husband's account)But let's not tell him were using it Wink

larryq99@yahoo.com!
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KG6AMW
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Posts: 616




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« Reply #1 on: August 09, 2003, 10:57:32 AM »

Hello Wendy. I use an AL-811 which is a fine and consistent performer.  But, the AL-80B will give you the option of using a little higher power when you want to (1000 watts peak versus 800 watts peak) and will most likely stand up a little better when operating digital modes. Next your dealing with just one tube in the AL-80B versus 4 tubes in the AL-811H and therefore don't have to worry about matching tubes to ensure highest performance. Finally the 811 tube has been in production since the 1940's and is found only in amateur radio. At some point it will cease production, but the 3-500 is in use not only used in amateur radio but also commercial broadcasting and other commercial uses. Either amp is fine, the AL-80B would be my choice for a new amp. Run it sparingly and don't disturb the neighbors. Good luck.

Merrill. KG6AMW
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W4CNG
Member

Posts: 177




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« Reply #2 on: August 09, 2003, 10:12:50 PM »

Both are good.  However, do not overdrive either.  There is NO difference in signal strength between 800 and 1000 watts on the far end.  You nor anyone else can see or hear the difference.  I can buy a couple of sets of 811A's vs the 3-500Z.  These tubes do not wear out as fast as most folks think when properly used.  Both amps are well designed.  Just do not let anyone tell you that 572B's will put out more power than the 811's.  The limit is in the power supply in the amp.  I own the AL-811H, which has the best power output for the money across the board.  One ham said it best years ago, "The first 500 watts of power is the most important step".
Steve W4CNG
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WB2WIK
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Posts: 20611




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« Reply #3 on: August 11, 2003, 01:09:43 PM »

I'd prefer the AL-80B of the choices posted initially.  More modern tube with almost assured future availability -- not so sure about the 811A (or even the 572B).  And the amp has more features, too.

But, I think more important: Don't buy a used amplifier via mail-order, from anyone you don't personally know; and don't buy a used amp you have not personally seen demonstrated, up close.  

Amplifiers are particularly subject to damage from shipment, especially when "used" and packed by an amateur.  Not worth the risk...get a local deal, see it work, and enjoy it!

WB2WIK/6

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W1DY
Member

Posts: 29




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« Reply #4 on: August 12, 2003, 09:05:00 PM »

How do you all feel about the solid state Ameritron ALS-600.

Would that be a better way for me to go?

I do drop down to 600 watts...but after all it is the first 500 that count.

The extra 400 of the AL-80B is nice to have...but if I start routinely pumping out 1KW I know I'm going to have "Neighbor Issues"

There are no tubes to worry over in a solid state amp...and if I do something stupid..the chance of doing damage seem minimized.

being a Computer Mode Junkie...is this just the smarter move for me?

And..Thanks to everyone that has responded here..and to my e-mail address..

I have learned that this hobby seems to bring out some of the nicest people!

Thanks again
W1DY
Wendy

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WB2WIK
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Posts: 20611




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« Reply #5 on: August 13, 2003, 01:36:17 PM »

The ALS-600 is a solid product.  I hear and work a lot of people using them, and haven't heard any negative comments.

Where did "the first 500W is the most important" mentality come from?  Not sure about that one.

Assuming most begin with 100W output power, increasing to 500W increases the transmitted signal by 6.9897 dB.  Increasing from 500W to 1500W yields another 4.7712 dB.  Going from 100W to 1500W = +11.7609 dB change.  So, the "first 500W" yields about half of what's available.

But, that's not the whole picture.  Far better to have a 1500W capable amplifier and actually use it at 750W than to have a 600W capable amplifier and use it at 600W.  Far better, especially for other people on the band!  When you own a 1000W (peak power) stereo system and actually run it to good speakers at about 60W output, it sounds really nice, doesn't it?  If you use those same speakers and a 60W system run at 60W, it usually sounds dreadful.  Same thing applies to RF power, unfortunately.

As for "neighbor problems," one doesn't know what's going to happen until it actually does; however, I've never noted any measurable difference in RFI complaints whether I'm running 100W or 1500W output.  If appliances are susceptible to RF interference, they are usually susceptible at pretty low levels.  I recall (not so fondly) operating from a town house (condominium) for a short period of time using attic dipoles.  If I ran anything more than about 40W output power, I'd key up the neighbor's smoke detectors!  It didn't take anything close to a kilowatt to make some real trouble.  And the trouble, of course, was with the smoke detectors.  

In that case, I offered the neighbor to replace his detectors at my expense, pulling out the "hard wired" ones that were AC-powered (the power lines make great antennas) and installing battery-powered ones.  Made all the difference in the world, and all the RFI disappeared, regardless of power level.

Most interference is the fault of the receptor, not the initiator, and needs to be solved there.

Advantages of a "tube type" amplifier, as opposed to solid-state:

-If the amplifying device fails, with a tube amp nearly anyone with a screwdriver can change the tube in five minutes and be back on the air; with an SS amp, this is usually a major repair job that can take several hours or possibly require factory service.

-Tube amps almost always employ adjustable wide-range matching networks internally, and most can easily load full power into a 3:1 VSWR without damage, derating or alarms; the SS amps employ fixed-tuned filter networks that must load into a close match, and if faced with a mismatch (even VSWR = 2), start "shutting down" to protect themselves -- to the extent of shutting off, entirely, in many cases.  This can be annoying unless all your antennas a perfect.

-That said, there are SS amps that have built-in automatic tuners so this last problem could disappear; however, those are the very high-end amplifiers that typically cost more than $2500, and do not include the ALS-600 and other low-priced SS amps.

73 & good luck!

Steve, WB2WIK/6
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W1DY
Member

Posts: 29




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« Reply #6 on: August 13, 2003, 08:32:53 PM »

Actually you answered the question yourself about the first 500 watts.


Going from 100 to 500 is only adding 400 additional watts.
This yealds almost 7 dB to the signal.

Adding another 1000 watts only gives an additional 4.7 dB.

Diminishing returns when you think of the actual Dollar premium you pay for that extra 1000W.

Extra money...go fo it....

Trying to maintain a budget for what is really a "Hobby" is another thing.

Would I like to have the 1.5 KW amp....Yup...but it's not gonna happen...

Wendy

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WB2WIK
Member

Posts: 20611




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« Reply #7 on: August 14, 2003, 01:55:50 PM »

Hi Wendy,

Now I know you must've been born after "Peter Pan" came out, because I think that was the first use of the name "Wendy" in history....

I'd prefer an old, used 1500W PEP amp which I can operate at 750W to generate a remarkably clean signal, as opposed to a brand new 750W PEP amp that I might try to operate at 750W, to generate animosity on the bands.  It really does come down to that.

Of course, we each have our own financial situation and I, too, look for a bargain!  Lacking a bargain, I build my own amplifiers from scratch, and have a shack full of them -- although I must admit when all is said and done, that's not a very inexpensive alternative.

Whichever way you decide to go, good luck with the new gear and hope to hear you on the air!

73 de Steve, WB2WIK/6
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W1DY
Member

Posts: 29




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« Reply #8 on: August 14, 2003, 04:37:51 PM »

I also was looking at the Skywalker KW solid state kit and building it myself.

But when I added it all up.. 250 for the plans and case..500 for parts..then needing (2) 70 AMP power suplies... it didn't make any sense.

So I think I have decided to start the search for a Good used Ameritron AL-80B.

Now here in Oklahoma City, I'm going to have probs finding one local. So it's off to the classifieds.

I just hope I can find one in good shape for a decent deal!

If I need to replace a tube ...no sweat...but I won't know if the amp has been abused until after I have bought it.


Thanks again for the help...

Any leads on a good al-80B that you'd like to share??

W1DY
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WB2WIK
Member

Posts: 20611




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« Reply #9 on: August 14, 2003, 05:21:28 PM »

Wendy, thousands of AL-80Bs have been sold, so hundreds ought to be available used.

I'd post a "WANT TO BUY" free ad here on eHam.net, and also on QRZ.com, QTH.com and ARRL.org stipulating you're looking for an AL-80B within "X" miles (driving distance) of Oklahoma City, and I'll bet you'll get a reply.

I would *not* recommend buying this amplifier used via mail-order or under any condition without seeing it, and trying it out, first.  Shipping damage is extremely common with amplifiers due to their weight and relative fragility and I wouldn't risk it, period.

WB2WIK/6
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K5UJ
Member

Posts: 54




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« Reply #10 on: August 26, 2003, 01:48:44 PM »

You say RTTY is your favorite mode so I assume you will be using the amp for that mostly.  I recommend keeping that in mind when you are looking, specifically two things:  the RTTY duty cycle and that usually RTTY signals can be copied well with less power than SSB.  A lot of amp power specs give a max pep output power for SSB operation which for RTTY you should probably divide by 2, or even 2.5 if you are going to transmit for several minutes.  Look for specs that give you a RTTY or 100% duty cycle power output value, or a key down power output and check to see if the mfr qualifies this with any time limits.  Some of the factors that vary the power specs from amp to amp (even ones using the same tubes) are the cooling employed (i.e. the "agressiveness" of the blower) and the power supply capacity.  A amp rated at 600 watts max p.e.p. for SSB will probably have to be run at around 300 for RTTY which to me, makes it almost not worth bothering with.
I'm not sure how much money you have to spend, but I would find a used amp from a dealer or manufacturer that runs at least 1.2 kw p.e.p. for sideband and run that at around 600 w. for RTTY, which I think would be enough for that mode (I have to qualify this by saying I have never operated that mode so I am by no means an expert).  Probably just about all amps using the pair of 3-500zg lineup will work.
I happen to know that Ten Tec sells their Centurion brand 3-500 amp used and reconditioned from the factory with a warranty for around $1400 or $1500.  Perhaps you can find a better deal face to face in your area.
GL
Rob
K5UJ
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N6AJR
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Posts: 9910




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« Reply #11 on: September 12, 2003, 10:06:37 PM »

I had them all from 811's to clipperton L and Bbe 33's and 34, and sweep tube amps.  I would reccommend you get the ameritron als 500 ( made for mobule use ) for about $650 or so new and a big used power supply like and ameritron 70 amper, or set up a battery and charger set up to run it off of at home ( outside, hydrogen gas..) I love mine, no tuning and a solid 500 watts on most bands, a bit less on 120 meters with the kit installed. ( or buy the 600 and it comes with a power supply but cost $1200...) I got mine on ebay for $300
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