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Shrunken Ebay 6-digit LED counter progress.

Discussion in 'CB Radio Modifications' started by nomadradio, Apr 16, 2018.

  1. nomadradio

    nomadradio Analog Retentive

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    It's beginning to look a lot like..... progress.

    Got the first couple dozen of these built and tested for eventual sale.

    [​IMG]

    Eventual. Still haven't tallied up my labor cost to decide on a price.

    Had to make a "test" counter board. Removed the large digits and installed machine-tool socket strips. Don't need the headache of selling a display that won't work. The finished digit boards plug right in.

    [​IMG]

    And once it's soldered to the chinese counter pc board it wouldn't be practical to remove. Better only to sell tested displays.



    I did discover that this display will *JUST* fit behind the clock window in a Realistic TRC-457 base CB.

    [​IMG]

    No, I don't plan to offer it as a display for that radio. The customer who asked for it knows that this radio does a squirrelly frequency dance when switching from AM receive to AM transmit. You can set it up to read LSB correctly **OR** USB correctly, or AM **receive only** correctly.

    The radio's PLL jumps 2.5 kHz when you go from receive to transmit in AM mode.

    The Chinabay counter only has one offset frequency. On the other hand, if you set it up to read USB correctly, it will also be right on AM transmit. But wrong by 5 kHz on AM receive.

    Just the same, it was an amusing install. It barely fits in place of the original clock. The plastic mount bracket is necessary to isolate the counter board's ground from the radio's chassis. If you let them touch, you'll get all manner of ground-loop noises in the radio's receiver audio.

    Gonna make the rest of this batch and decide how much to charge for just the digit board alone, or the assembled unit ready to install.

    Gotta figure anyone who wants to buy the PLJ6-LED counter board and remove the big digits himself will want to buy a few. They're cheap, and I screwed up a couple of the first ones I modified. The quality of the San Jian circuit board is pretty good, but it's not terriby robust when you start removing stuff.

    More soon.

    We always say that.
    73
     

  2. loosecannon

    loosecannon Sr. Member

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    Are you planning on making up some cables so that the freq counter itself can be mounted elsewhere?
    LC
     
  3. nomadradio

    nomadradio Analog Retentive

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    No, this is strictly a "piggyback" replacement for the too-large digits that come with the original 6-digit display.

    Long cables would become a noise issue. The LED digits are multiplexed, switched on and off in sequence, fast enough that they appear to be continuously illuminated.

    The square wave on/off current feeding the digits will radiate RF noise all along the wires. It tends to leak into the receiver audio.

    Making it 'remote' just doesn't look practical, IMHO.

    73
     

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