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Alinco DX-70 160m 10m issues

Discussion in 'Radio Circuits, Repair & Performance' started by N1EBC, Sep 2, 2019.

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  1. N1EBC

    N1EBC Ham Member QRZ Page

    I've got a Alinco DX-70 all bands but 160m and 10m seem to work fine.
    on 160m an 10m output is low and nowhere near correct frequency. Does anyone have any suggestions?
    Handy with an iron, an have a scope.

    Thanks for any advice.

  2. G3YRO

    G3YRO Ham Member QRZ Page

    More details would help . . .

    How low is the power output?

    And how far off frequency?

    Roger G3YRO
  3. N1EBC

    N1EBC Ham Member QRZ Page

    about 5watts transmit on 28.375 shows 5.something on the frequency counter. I'm kinda of leaning towards the pin diodes on the bandpass filters.
    Tuning the VFO sometimes in 40m you hear what sound like relay clicks.

  4. G4COE

    G4COE Ham Member QRZ Page

    Have you tried a factory reset?

  5. N1EBC

    N1EBC Ham Member QRZ Page

    No I have not. I'll look that up.
  6. G3YRO

    G3YRO Ham Member QRZ Page

    What do you mean?

    Are you saying that when the rig's display says 28.375, a frequency counter says it's 28.5xx ?

    If the WRONG frequency band info is coming out of the PLL, then the WRONG switching signals will be sent to the transmitter output bandpass filters (ie the wrong bandpass filters may be switched in circuit)

    Bear in mind that if this is happening you MAY damage your PA transistors (because they would be generating lots of power that isn't getting to the antenna socket) . . . so only transmit in very short bursts!

    Roger G3YRO
  7. N1EBC

    N1EBC Ham Member QRZ Page

    No I mean radio show 28.375 and the counter will show like 5.250 or something similar.

  8. K5DH

    K5DH Ham Member QRZ Page

    The problem with failed diodes on the filter board is well known and well documented. That would certainly affect power output. It should not affect frequency.

    Have you tried transmitting on the DX-70T into a dummy load and listening on another HF receiver to see if your rig is really on frequency?

    How do you have the counter connected to measure the signal? Are you over-driving or under-driving the external frequency counter? Is RF getting into the external counter and confusing it?
    Last edited: Sep 5, 2019
  9. N1EBC

    N1EBC Ham Member QRZ Page

    I will reset the dx70 then put it into the cantenna.
    Right now setup is dx70>mfj993 autotuner> digital swr meter>antenna
    The autotuner reads the frequency.
    We will see how it goes after reset. For now I'll stick to the dummyload.
  10. WA4SIX

    WA4SIX Ham Member QRZ Page

    Take the autotuner out of the system. See what the meter reads then. A dummy load is preferable.
    THe radio might be fine & the autotuner may be acting wrong.


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