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HOMEMADE BASE STATION MONITOR and SWITCHING CENTER

Discussion in 'Home Brew' started by unit_399, Feb 15, 2011.

  1. unit_399

    unit_399 EL CAPO

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    I’ve been experimenting with my base radio for a long time, and it’s good to go on the transmit side. Now, I’m working on the receiver to improve sensitivity and reduce noise. The transmit mods (3:1 speech compression, switchable NPC, etc.), were installed inside the chassis. But the receive equipment (equalizer, audio compander, speech filter, and DSP) were larger and needed to be connected externally. I use separate setups for AM and SSB (including a different speaker for each mode), and reaching behind the rig to change connections when switching modes was a pain in the ass. The solution was to build a switchbox and change setups by pushing buttons. It worked, but like anything I build in two nights....it looked butt-ugly.
    The second-generation box took longer to build, but it looks nicer and has more features. The new box has three meters: S , RF, and Vu (modulation). The stock S/RF meter on the TRC-457 is hard to read, and the new Vu meter makes setting up the NPC easier. There is also a switch to control the fan in the 457. The NPC mod increased the transmit duty cycle and fried two AM regulator transistors, so I put in a fan to cool things down. BUT.... the fan fed noise back into the supply and the 457 "whined" in receive. Now the fan gets its power from the switchbox and the whine is gone.
    This was a fun project and came out better than I expected.
     
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    There are other pictures posted on my member page.
    - 399
     
    #1 unit_399, Feb 15, 2011
    Last edited: Feb 16, 2011

  2. GnG8d

    GnG8d Well-Known Member

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    Very nice!
     
  3. loosecannon

    loosecannon Sr. Member

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    very cool!

    be sure to let me know when they become available for purchase. LOL

    how exactly does the Vu meter help set up the NPC?

    knowing you, im guessing that you arent using the stock 1419 for the reg., so what part are you using that kept blowing?
    LC
     
  4. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

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    That's the kind of workmanship I like to see and not something that looks as if it was beat with an ugly stick. Nice job!
     
  5. MrSuburban

    MrSuburban Guest

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    I am not gonna lie that is a nice job, but what impressed me more in your pics is where you live. Do you need any help down there. (y)
     
  6. unit_399

    unit_399 EL CAPO

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    Thanks everyone for the nice comments.

    Mr 'Burb-
    Like they say on The Price is Right....COME ON DOWN !

    Loosecannon -
    I replaced the 2SC1419 (2A 10W dissipation) with an ECG152 (6A 50W). I'll pm you with the other info.

    -399
     

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