Kenwood 820S Squeal

Discussion in '"Boat Anchor" & Classic Equipment' started by KE8HIG, Sep 12, 2017.

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  1. KE8HIG

    KE8HIG Ham Member QRZ Page

    I have a Kenwood 820S that emits a squeal when the RF Gain is turned fully clockwise. Turning it back about 1/4 of the way makes the squeal go away but I am surely loosing sensitivity. Any ideas?
  2. N8YX

    N8YX Ham Member QRZ Page

    Does the squeal follow the VFO tuning, or is it constant?
  3. KE8HIG

    KE8HIG Ham Member QRZ Page

    I am at work right now but as I remember it is constant with the VFO and only varies/diminishes by turning the RF Gain control.
  4. N8YX

    N8YX Ham Member QRZ Page

    Does it change in volume with the AF Gain control or is it constant amplitude? And is it present on all modes, or just one?
  5. KE8HIG

    KE8HIG Ham Member QRZ Page

    It is present on all bands and modes. The AF Gain Control does change the volume of the squeal.
  6. N8YX

    N8YX Ham Member QRZ Page

    First thing I'd do is look at the T/R changeover relay. It routes muting and AGC voltages to various circuits in the transceiver. I had a similar condition occur with one of my R-820s and this was the problem.

    Do you have the TS-820S service manual?
    KD2ACO likes this.
  7. K9MOV

    K9MOV Ham Member QRZ Page

    I have an original TS-520 that developed many " goofy" problems, one of which you describe. I put it on the restore bench thinking at the very least I would have to do a RECAP. I recalled a tip from many years ago about the Kenwood hybrids that I tried first. Loosen and retighten all the ground screws on ALL the boards. This cured 100% of all the problems I had with the radio. It still is all original and works like new.
    I hope this will save you many hours of troubleshooting.
    KD2ACO likes this.
  8. N8YX

    N8YX Ham Member QRZ Page

    820 series were sometimes noted for poor connections with the push-on connectors used for inter-module cabling, but in all the years I've played with and worked on that line (30+) I've never encountered a bad board ground as was common with the later (X30-series) hybrids.
  9. KD2ACO

    KD2ACO Platinum Subscriber Life Member Platinum Subscriber QRZ Page

    My 820 had "all of the above" :p
    Molexia, fixed by wiping the pins with a deoxit moistened tek-wipe. Broken wires at the connector pins, leaking caps, mis alignments, etc.

    Took some time to get it all going, but the effort was worth it!
    K0OKS likes this.
  10. KA9JLM

    KA9JLM Ham Member QRZ Page

    Is that the radio with the broken MONI switch ?

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