IC-735 Receive problem

Discussion in 'General Technical Questions and Answers' started by AC1DV, Jul 11, 2018 at 2:51 PM.

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  1. AC1DV

    AC1DV Ham Member QRZ Page

    I have the IC-735 working flawless since new. (yea I don't buy a lot of rigs..) Now all of a sudden at about 14.304 the receive cuts way Down. Not even sure it is receiving. Except as I go up in frequency after that it starts popping in and out rapidly. The higher the frequency the faster the speed of the in and out cuts. After going around the other bands and finding no other trouble went back and now the cut out is about 14.320. It seems to drift higher. Never heard anything like this before. And it seems to only happen on 20 meters range. no other bands. The antennas I use all check out and it actually will transmit in that range. But can't receive.
    Any ideas??
     
  2. N4OGW

    N4OGW Ham Member QRZ Page

  3. N5DMC

    N5DMC Ham Member QRZ Page

    To test the variable caps that are located under the 2inch x 1inch raised steel metal cover do this.

    1) mark with sharp instrument the clock location of the adjuster inside each of the 4 holes. Notice the arrow point only in a single direction.
    2) at the home store buy some 99% painters alcohol. Not rubbing alcohol, not 90%, get the 99%.
    3) drop just 2-3 drops in the one hole, spin the adjuster back and forth quickly (Apx 20 times) returning the pointer to your scribe mark on the top of the metal box.
    4) repeat each step and perhaps twice to make sure.

    Also be sure to notate where EXACTLY all the plugs go. And the direction they interface. Don't be in a hurry. Use some tape and fine point sharpie and mark your way around. Actually there should not be easy to mess things up n there, but you'd be surprised what some will do.

    While you're in there, consider the MARS mod. Tighten all the PCB mounting screws, including inspection in the PA area. You will find lots of loose screws.

    This trouble shoots the variable capacitor issue which is well known. Pretty difficult to repair yourself. Let a specialized tech do this. This fix if done correctly should last 6 months of daily use.

    Be very careful and put the same length screws in the same place they came from. Now, enjoy a great radio once again.

    Also, there is a clear masking film in the linear adjustment area, behind the clear plastic door. If you are growing fuzzies around the cut out slots, you have a film that will come off.

    Good luck & let us all know how you do.

    Doug
    N5DMC
     

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