Dual 3-500's or a 3CX1500??

Discussion in 'Amateur Radio Amplifiers' started by HK2LS, Apr 2, 2012.

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  1. HK2LS

    HK2LS Subscriber QRZ Page

    Right now I have an AL80B - it works fine - I just want something with more power.

    The AL80B works well and doesn't need a long warm up. The options I'm considering are the AL-82 and the AL-1500. Right now with the AL80B I get 1000 watts on 40 and 900 watts on the other bands except 10 I get 690 watts. I would assume with the AL82B (dual tubes) I could double these amounts (is this a correct since the power supply claims to be able to handle both tubes at a full load - I don't know if this is indeed reality).

    Now the AL-1500 with a single 3CX1500. This requires a 3 minute warm up - so could I assume that his would put out 3 times the amount of power as the AL80B??


  2. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    With proper cooling it possibly could, but the AL-1500 uses just enough cooling to sustain 1500W output power as a compromise between power and blower noise. Many say it's already a bit noisy as it is, and they run the fan on the lower speed which restricts how much power the amp can run. On full speed, it's good for 1500W with a high duty cycle. Above that -- I wouldn't go there.
  3. W1QJ

    W1QJ Ham Member QRZ Page

    Larry, to answer your question. We have to make certain assumptions to answer your question. First, lets assume your maximum output power for driving an amplifier is 100 watts. That said, lets see what these amps in question will give you. The AL-82 runs a pair of 3-500's, they are instant on and you can transmit pretty much as soon as you flip the switch. If you put 100 watts into an AL-82 you will get 1600 watts output (key down). I've had several of them that I owned and several that I have repaired and although this figure may vary slightly, 1600 watts ouput is about it. Of course if you drove it with more power it will make more but we are assuming 100 watts drive so the number you should use is 1600 watts output. Now, for the AL-1500. it uses the 8877 tube, it takes 3 minutes to warm up before you can transmit. I have had about 2 times as many of these amps as AL-82's and I have seen 1500 watts output (key down) with as little as 50 watts up to about 65 watts. If you go ahead and give it a full 100 watts of drive you will see between 2250 to 2500 watts output (key down). I suppose the difference here is in the tubes. But the least amount of power I have seen from an Al-1500 with a decent tube with 100 watts is 2250 watts output. The fan in these amps have different speeds you can select. The fan speed is selected through several taps on the filament transformer primary. The go from 90v to 120v in 3 or 4 steps. Although Ameritron did not do this, the hot set up would be to have a DPDT relay in parallel with the antenna relay and switch the highest tap on the fan in on transmit and a lower (more quiet) tap in on RX. Another amplifier in this catagory is the AL-1200, this runs a 3CX1200. This is a very rugged tube and can take a beating. it is instant on like the 3-500's. The stats on this amp are in between the AL-82 and Al-1500. If you were to put 100 watts into this amp you will see 1800 watts output. i have owned and repaired several of these also and they are pretty much right on the money at 1800 watts output. I once saw a 3CX1200 in an AL-1200 that I repaired that turned blue. You know that blue color tha metal turns when you get it red hot? That kind of blue. Well to my surprise, that tube was STILL full output. It's a great tube. Problem is, if it goes, even a good used one is BIG BUCKS! Hope this helped. Lou
  4. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    Hum. Spending about $1,000 USD (at least) for about 2 to 3 dB more, seems like a waste of time.
  5. HK2LS

    HK2LS Subscriber QRZ Page

    I am using a TS-590 which is rated for 100 watts PEP. The AL80B is connected to 120 VAC - given this I think I could increase the power by 5% if I connected the amp to 220VAC since our 120 runs from 120 to 127 and drops by 5 volts when I transmit. The 3XC1200 I know is very expensive as compared against the 8877 and the 8877 is available as medical pulls for substantially less money than a brand new tube.

    I would like a solid state amp however since I live in Colombia and shipping from here is so expensive - I don't want to be in a situation where I need to send the amp back for repairs - thus I stick with something that I have a high chance of being able to repair myself which I think would be the Ameritrons.

    So the AL-1500 you mentioned you have seen more of vs the AL-82s for repairs so can I assume there are more problems with the AL-1500 amps vs the AL-82s?

    Thanks in advance --

    73s from Colombia..
  6. J85K

    J85K XML Subscriber QRZ Page

    I am very pleased with my choice......

    I just got a used Alpha 99 and I'm pretty happy with it. Quiet, dependable and the LED's aren't bad looking either. I did consider (used) Ten Tec Titan 2&3, QRO 2000/2500, Acom 1000/2000A etc.

    Here are a couple of links to assist you:



    In the solid state department, I would personally try the SPE (2K-FA) line of amplifiers. It has a nice torodial core transformer that is very efficient at keeping RFI at bay. Also is 230volt 50 hertz, which is perfect for me.

    Good Luck!!
    Last edited: Apr 3, 2012
  7. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I repair amps quite a bit and I wouldn't say the AL-82s or the AL-1500s fail much, other than from "cockpit error," such as turning the bandswitch while transmitting or some other mistake.

    They're both very robust amplifiers. If you use them carefully they should last many, many years.

    The Eimac 8877s are very good. I haven't used the Chinese ones yet and don't have any real experiences with them.

    I have 8877 "pulls" in two of my amplifiers, they were both 5-10 years old when I got them (never bought a new one!) and 20-30 years later they still both run 1500W output power. I can't say the Chinese ones are this good, but possibly they are.

    I don't really like the 2-3 minute warmup "wait," it's kind of a pain. But for VHF and UHF, the 8877 is the only reasonable choice and that's where I use them. 3-500Zs work great at HF and also on 6 meters. Eimac hasn't made one in many years, and now they're all Chinese. But I've been using them from RF Parts (their "brand") and although they are certainly Chinese, they offer a good warranty and if they fail, they'll replace them. And they're still pretty cheap.
  8. W1QJ

    W1QJ Ham Member QRZ Page

    No, the AL 82 does not break down any more or less than the AL-1500. All three amps,
    AL 82/1200/1500 are basically the same. Only difference is tube, filament transformer and relatrd items. Power supply, tank circuit etc all the same. Only reason I have seen more 1500's is because I bought more of them for myself. They are simple amps, easy to work on and repair. You should never have to ship it back for repair. If you can solder you can repair it. Something goes wrong let me know and I will tell you what the problem is. They have their basic weak spots that usually are the problems.
  9. AG6K

    AG6K Ham Member QRZ Page

     You might get double that power with an 8877, however a factory stock AL-1500 needs at least two modifications: 1. An additional 450V filter capacitor to provide a safety margin between the HV filter's WV and the actual V. 2. A low-Q VHF suppressor to reduce the extraordinary VHF gain of the 8877 - thereby making it more stable at VHF and UHF and avoiding a possibly fatal episode of gold sputtering off of the 8877's grid.
    I would also check to see if the AL-1500 has a jumper between the cathode and the heater, a bifilar heater choke, neither side of the heater is grounded, and it has at least 30-ohms of glitch-R in the HV+. It's also a good idea to put a 3A diode (anode to gnd) between HV negative and the chassis to keep the HV negative from spiking to more than –1V during a HV+ to chassis arc.
  10. KM1H

    KM1H Subscriber QRZ Page

    Perhaps I see more Ameritron amps due to the ham concentration in this area and contesters but of the 3 big ones the AL-82 is the most troublesome as its running the tubes close to the edge and even Eimacs used to arc internally and take out a LOT of components. With Chinese tubes its a lot worse.

    The Al-1200 has been thru 3 tube versions and a replacement is about the cost of a pair of Chinese 8877's with have excellent reputations. Plus the 3CPX1500A7 version is readily available as medical pulls at full output or darn close for around $300.

    I almost never get a AL-1500 in for service and then its usually an admitted cockpit error.

    Ameritron admits that the 1500 is their biggest seller by far with the 82 way down around 250 a year and the 1200 at maybe 100.

    Their one common fault is the ridiculous step start used. The relay contacts become welded and take out the fuse. Those that use a bigger fuse take out the transformer. Buy a spare relay and a box of fuses.

    I know what my choice would be.

    The AL-80B has the same problem as the 82, when a tube goes bang reach for your credit card.

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