Is it time for amplifier mfgrs to step back and "rethink"

Discussion in 'Amateur Radio Amplifiers' started by KM5FL, Sep 6, 2011.

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  1. AF6LJ

    AF6LJ Ham Member QRZ Page

    Just one question;
    How would one of these devices preform if it was subjected to one millisecond spikes twice it's maximum drive rating day in and day out?

    You can do this with many, not all tube amps but I wouldn't even think of trying this with any transistor based amplifier.

    I'm not by any means against solid state amplifiers they have advantages.

    Amateur amplifiers have to be engineered to work with any radio good bad or indifferent.


    That is cheap but I wouldn't put that behind my IC-756, not with that radio generating 125+ watt spikes on transmit.
     
  2. K7JEM

    K7JEM Ham Member QRZ Page

    Somwhere I read that they can take double the design input without failure. But almost any radio is going to require a pad between the radio and amp. These transistors have like 55 dB of gain, maybe more. So, no more than 5 watts to drive it to 1200 watts out.

    Joe
     
  3. KM1H

    KM1H Ham Member QRZ Page

    There are several classes of amplifier owners.

    1. Clueless. Many come from the CB ranks and never had to tune anything in their lives. IMD is an unknown term.

    2. Elderly long time hams. Cant remember if they tuned up or not so do it for 10 minutes to be sure. After destroying several cheap Ameritron amps they want SS and no tuning.
    2a Similar but younger. Ability to do anything is in inverse proportion to alchohol intake.

    3. Money is no object. Want everything ready as soon as they sit down, allergic to anything involving manual interface. If their $13K Alpha gives a fault code they call their lawyer first.

    4. More technical type, happy with a manual tune tube amp and understands how fragile some of those ceramic tubes are to mistuning and oops, another $1000-2000 out the window. Can do simple repairs.
    4a Similar to 2a; sometimes fries himself.

    5. Real techy homebrewer. Uses real tubes such as YC-156, 3CX3000A7, some Ruskies, even a pair of 4-1000A's, etc. The grids can be used as dummy loads for the exciter. If he has a store bought amp he can fix anything needed and if it uses expensive tubes due to age something cheaper has been retrofitted.

    6. Real techy nerd type, not satisfied with anything not at the leading edge. Blows expensive SS devices but just begs for more "samples" until the damn thing finally works. Then tells everybody how easy it was and he is just so superior to the masses.
    6a Alcohol not a problem, other chemicals take precedence. HV usually not an issue.

    While much of HF is atmospherically noisy or just plain crowded a -30 IMD single tone is more than sufficient but once the quiet bands are involved which is genarally 17M and up poor IMD is easily heard.

    Once into VHF where there is little or no band noise a poor radio/amp stands out like a sore thumb. Unfortunately most if not all of those DC to daylight allbanders are pure garbage. I use very linear transverters driven from the Class A low level stages of the HF transceivers and into mostly HB amps (6M is converted from HF) made as linear as I can get them. Since the SSB/CW portions of the bands are so narrow the equipment is tuned once and left alone so Im all set for my senile citizen years.

    Carl
     
  4. WB0LSR

    WB0LSR Ham Member QRZ Page

    NVM, not worth the effort.
     
    Last edited: Sep 10, 2011
  5. W4AFB

    W4AFB Guest

    With a nice beam and 200 watts i hardly ever even fire up my amps, which by the way are both toobs.
     
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I like tube tops on young ladies. Thankfully I get to see them 52 weeks a year here, and they're often S9+.

    I use my amps quite a lot, mostly because a lot of stations seem to not hear very well. I just now called a guy on 20m who was 56-57, and I used 100W to my beam. All I got was "QRZ?" Twice. I turned on the amp and he heard me fine. He was only running 100W, so now I was running 10x his power.

    This happens a lot. I don't know if it's operator inexperience or just that people have high noise levels. Whatever it is, an amp helps.

    Interestingly, I get into DX pileups pretty often running just 100W and the DX stations hear me just fine. But those are usually highly experienced operators, and probably mostly in low-noise locations.
     
  7. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    I haven't read this whole thread, but I've read enough to form a few opinions.

    First, far too many amateur do not know how to tune an amplifier. And, far too many take to long to do so, even when they know how. If nothing else, it assures the rest of us will have a supply of tubes.

    I also believe, that the vast majority of amateur don't know how to adjust their microphone gain and/or use compression as if God commanded it. As Steve, WB2WIK, might say—AKFR, all knobs fully right!

    Further, too many use too much power, all of the time (they must not care how big their electric bill is). If the station you're talking to is S9, why the heck do you need an amplifier?

    And lastly.... The legal limit is 1,500 watts. Why buy an amplifier capable of 3 to 4 times this amount? Oh! I forget! They want it to run cool! Well, I just think their thing is too short, and they're trying to make up for its shortcoming.
     
  8. AF6LJ

    AF6LJ Ham Member QRZ Page

    That wouldn't be a problem. :)
    If they truly can take that much then they make a really good choice.
    I've seen the datasheet on those devices and they look good.
    The IMD is really good at half power.
     
  9. AF6LJ

    AF6LJ Ham Member QRZ Page

    I like that may I print it :)
    The types of amplifier users that is :)
     
  10. W4AFB

    W4AFB Guest

    I have an S-3 to S-8 noise level here right now thanks to crappy power lines. Im pointed towards Cali right now.
     
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