Ameritron Amplifier Advice

Discussion in 'Amateur Radio Amplifiers' started by VE2GCE, Mar 28, 2019.

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  1. VE2GCE

    VE2GCE Ham Member QRZ Page

    I was comparing the Heathkit SB-220 (2 x 3-500Z) vs the Ameritron AL-80B (1 x 3-500Z)

    The specs are as follows:
    SB220
    SSB output is 2000 watts PEP
    CW output is 1000 watts
    RTTY output is 1000 watts

    AL80B
    SSB output is 1000 watts PEP
    CW output is 800 watts
    RTTY output is 500 watts

    So is the SB200 underrated for CW or is the AL80B overrated for CW ?
     
  2. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    ^^^ Oops, different ways of measuring power in the SB-220 days. ^^^

    2kw input is about 1200 w PEP output for the Heathkit.

    Think, "55-60% efficient" and multiply power input by that to get power output... 60% is with the wind at your back! :p
     
    VE2GCE likes this.
  3. VE2GCE

    VE2GCE Ham Member QRZ Page

    Thanks Chris, You are correct the SB220 numbers were DC input.
    So if we correct my table, we get the following normalized values at 60% efficiency.
    This means the AL80B with one 3-500Z is putting out almost as much power as the SB220 with two 3-500Z. (More in the case of CW)

    SB220
    SSB output is 1200 watts PEP
    CW output is 600 watts
    RTTY output is 600 watts

    AL80B
    SSB output is 1000 watts PEP
    CW output is 800 watts
    RTTY output is 500 watts
     
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The SB-220 can't run 2000W PEP output; that was an input power rating.

    The AL-80B actually has a beefier power supply than the SB-220 had; the SB-220 couldn't come close to operating the tubes at full potential power due to power supply and cooling limitations.

    The AL-80B can almost achieve the full potential power from a 3-500Z, although doing so it does exceed the 3-500Z anode dissipation ratings; however the ratings are for continuous duty (such as broadcast) while in the amateur service we operate mostly fairly low-duty cycle modes. The AL-80B must be run at reduced power on FM, RTTY, digital modes and reduced a whole lot for AM.

    Anyone who ran an SB-220 on RTTY at 1000W output power burned up the power transformer and now is using a different one.:p
     
    VE2GCE likes this.
  5. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    The interesting thing is that (2) 3-500's can really put out a bunch more power (like legal limit in SSB for example) if the rest of the chassis could support it. In the SB-220's case, you run out of grunt (or there is too much heat involved) in the power supply... and the AL-80B specs are Ameritron watts, which are a bit smaller than Real World watts, so that number is a bit bigger than it should be. :D

    One could stick with those numbers, but I don't. Keep an eye on the tube while doing trials to not run it too hard in the heating department, and you'll find the safe zone. My Ameritron Multiplier is about 80%.

     
    Last edited: Apr 10, 2019
    W1BR and VE2GCE like this.
  6. N8FVJ

    N8FVJ Ham Member QRZ Page

    If you have a SB-220 a replacement Peter Dahl Hypersil transformer will provide full legal power output. Transformer makes about 300-400 more volts under load. It was reported on eHam to just make 1500 watts out on 75 meters with 100 watts drive. The Peter Dahl transformer output is 1.3 amps vs original .7 amps output. Transformer is $395. You can sell the original transformer for $100 to help the Peter Dahl purchase cost. I seen a few SB-220s for sale with this heavy duty transformer for under $1K or about same cost as the AL-80B. I am tempted to sell my AL-811 for a SB-220 with the Peter Dahl transformer as I do not use 160 meters.

    HEATH SB-220-3-7 EXTRA HD REPLACEMENT FOR SB-220 / SB-221 / HL-2200
    WITH CUSTOM 7 MIL C-CORE [​IMG]
    NOTE: Requires mechanical modifications (cut out) to the
    internal perforated top panel of the amplifier (not the cabinet).
    For photos see Dennis's (N9AD) installation photos.

    CORE) B-0393/ (SIDE MOUNT) STYLE #) 10 HIPERSIL C-CORE
    PR) 117/234 VAC 60 HZ HI-LO TAPS S1) 860/1171 VAC @ 1.3A CCS

    DM) HT = 6.25 WT = 5.25 DT = 5.0 MD = 3.375 MW = 4.50 PRICE) $394.86 Plus S&H FOB Buffalo, NY WEIGHT) 23 LBS
     
    Last edited: Apr 12, 2019
  7. KA9JLM

    KA9JLM Ham Member QRZ Page

    OUCH

    How much did the SB-220 sell for new ?

    A better power supply can smoke the tubes much faster.
     
  8. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    I think the tubes can do it. It's the rest of the frame I'd be careful with.

    (Buy or make a nice PCB with a couple extra caps in line for example, and optimize the cooling situation)
     
    KA9JLM likes this.
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The SB-220 also needs cooling improvements to run 1500W output power; the weak link is the cooling below the tube sockets (filament pins).

    There are ways to accomplish this.
     
    W1BR likes this.
  10. W1BR

    W1BR Ham Member QRZ Page

    I'd worry about the tube cooling in the SB-220 if one were to push the power rating by modifications to the power supply. SB-220 isn't going to work on all WARC bands, and it does not cover 160 meters. Those are two marks against it. I spent a winter adding WARC and 160 meter coverag along with vacuum relay QSK to my SB-220, along with automatic bias switching and many other changes. when the dust settled out of pocket costs were in the area of 400 or 500 dollars. Not sure that was economical, but the amplifier works great and the project was more something to do and a learning exercise.

    Besides the AL-80B, the AL-1500 would be on my short list. My main amp these days is a used ALS-1300.

    Pete W1BR
     

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