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DaveMade 2X4

Discussion in 'Amplifiers' started by RunAway15, Apr 20, 2017.

  1. RunAway15

    RunAway15
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    So I'm gonna ask again, what exactly is the RF PWR knob on my box for? I know it lowers the carrier on the box, but is that really padding the input? I am driving the box with a General Lee and the opinion is spilt that it's too much vs not too much. When I set my low side to DK into the box I am dumping about 400 watts into it (changes with different lengths of coax) but I don't have a variable on my radio to adjust it and when I adjust it on the inside it will either not DK or DJ too much. I Read somewhere else that it's to drive other boxes, and to always run it wide open. But i also read another place that it actually pads the input of the driver in this box. And that it's not good. I am confused.


     

  2. LeapFrog

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    NOT having ever looked inside a Davemade box..

    I say that I think it is an input padding, and the recommendation to leave it "wide open" is out of fear that someone might burn out the resistors or variable (on that input pad circuit) by generally over-driving the input with a hot radio.

    If you lower (attenuate) the input signal, the carrier (or output of amp) will drop also.
    But this is simply conjecture, and someone more experienced will need to chime in.
    73
     
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  3. BBB

    BBB
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    I would run a radio that has a variable single final only into that 2x4. Dead key should be 100 watts max on the output of the amp if it has (4) 2sc2879 transistors in it. Let it swing up to 400+ watts. Less DK if it has (4) 2290s. Make sure the fan works ;)

    Yes you can adjust the dial on the 2x4 which pads the input a bit. It is common for those 2 watt potentiometers to fail altogether or get dead spots in them. Rarely would you run that wide open unless you can vary the output power of the radio which unfortunately your radio can not do. You can find the replacement pots on Mouser Electronics site. Get all the info from the old potentiometer and get an exact duplicate. They cost more than the cheezy radio shack pots and never use a wire wound pot in an RF application.

    Hope it works out for and you don't let the magic smoke out.


    [​IMG]
     
    #3 BBB, Apr 20, 2017
    Last edited: Apr 21, 2017
  4. Crusher

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    BBB, those are 2w potentiometers. Just a heads up. 100ohm.
     
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  5. BBB

    BBB
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  6. 9C1Driver

    9C1Driver
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    I think you meant to say with your General Lee on Low the amplifier has a 400 watt dead key out when running wide open. I don't think your radio is dead keying 400 watts in as you put it.

    That said those variable pots are always the week links in most amplifiers. They are 2 watt pots and most people will dead key more then that in and then in time it burns a spot on the pot.

    Davemade kinda does their own thing. I have always felt any amplifier with a driver stage (1x2, 1x4, 2x4,2x6) were very much low drive amplifiers. Davemade however claims they add some swamping resistors (padding) to gobble up the excess wattage so sometimes they refer to their 2x4 as a high drive. I was told this over the phone from them once.

    If your General Lee is properly set up so the low carrier is 2 watts you should be ok. Best bet would be to have everything hooked up, watt meter after the amplifier and the amp on high (variable wide open).
    With the radio cover off and a plastic tool in the AM VR pot and dead key the radio, then turn the AM power pot back and fourth. You should see the carrier wattage on the meter rise and fall. Turn it down so the amp has a dead key out of 100-125 watts. Done. It might be 1 watt, 1.75, could be 2 watts.
     
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  7. RunAway15

    RunAway15
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    Yes, that's what I was talking about, the box is DKing 300-400 watts. I already have the VR doing less than a watt in the General Lee, i go lower it won't DK at all.
     
  8. BBB

    BBB
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    Magic smoke countdown...

    [​IMG]

    You should be able to adjust that pot (knob) on the amp to get it lower than that, if not that potentiometer is toast and/ or that radio amp combo is giving off some crazy harmonics.

    Is there any squealing on the outbound audio someone nearby could verify?
     
    #8 BBB, Apr 21, 2017
    Last edited: Apr 21, 2017
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  9. BBB

    BBB
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    [​IMG]
     
  10. BBB

    BBB
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    [​IMG]
     
  11. RunAway15

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    I can get it down to about 250 with the knob on the amp, but shouldn't I be able to get it down with the amp wide open just using the radio VR? No squeal no where. All I get is good reports on it.
     
  12. RunAway15

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    Nothing in the amp gets hot.i know because I've often put my hands on components inside the amp. That may sound weird or funny but I've had this amp for ten years this summer so something I do is working. Have only run it with a General Lee. I keep my transmissions short and sweet. I know how to keep from smoking it, I hope. That's why I'm posting on here. Not using it that much at all until I get this figured out. My SWR is spot on. If I use some cables that let my SWR suffer I can adjust it ever how I want, but I know those are just ghost watts and not a true reading.
     
    #12 RunAway15, Apr 22, 2017
    Last edited: Apr 22, 2017
  13. 9C1Driver

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    Maybe that amp was set up to be run as a "maul". Some times they like a giant dead key that actually swings backwards when you talk. Lol, that's not my thing but they do it.
     
  14. BBB

    BBB
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    Watt meter out of calibration showing too many Happy-Watts perhaps? All too easy to turn the pots inside a watt meters to show inflated output power. I would get a second and third watt meter opinion if possible. I'd think a 400 watt DK out would get a 4 pill box hot pretty fast. Like running FM mode.
     
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