IC-7300 plus linear amp warning

Discussion in 'Software Defined Radio (SDR)' started by G0GSR, May 21, 2019.

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  1. N3EG

    N3EG Ham Member QRZ Page

    Just wondering...is there a hot switching key-up delay now that needs to be compensated for with this mod?
  2. G0GSR

    G0GSR Ham Member QRZ Page

    The capacitor mod only affect the amp OFF timing.
    "TX delay" setting is still good for ON timing.

    Yes, good point.
    We noticed a similar thing with the Kenwood TS-590 firmware recently, where a fan start problem was resolved but no mention in the release notes.

    But I feel that the CEO/President of Icom should now do the honourable thing after knowing about this fault since 2016 and NOT fixing it.

    Last edited: Nov 1, 2020
  3. SM0AOM

    SM0AOM Ham Member QRZ Page

    I believe that not taking notice of user or customer input can be quite representative for Japanese radio industry.

    About 20 years ago, I had the opportunity of discussing a related topic with the service manager at the Nordic Icom representative.

    He claimed that it was virtually impossible to make the designers change anything based on feedback from the user base.

    Had they decided, after careful deliberations, for a certain solution, it was "final", no matter how convincing the arguments could be. This was said to be valid for both "large" and "small" issues, and had a cultural background.

  4. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    Seppuku? :eek:

    for want of a minus sign in C++...
  5. N3EG

    N3EG Ham Member QRZ Page

    Similar situation with a popular camera manufacturer - they keep charging customers for warranty repairs on a weak tripod mount design.
  6. VK4CAN

    VK4CAN Ham Member QRZ Page

    Yes I have taken this up with Icom Australia and initially I got fobbed off with "it's adjustable in the menu". I eventually got a response after pointing out the issue was actually not the RF On timing but the RF Off timing. The local Icom engineer finally agreed but said it would be a difficult and slow process as this was something that would need to be altered in firmware. I understand that both from a cost POV as well as altering software in something as complex as is running on the ARM CPU in the 7300.

    That said I am not confident anything will become of the matter anytime soon or indeed if at all.

    Interim I guess it's either the capacitor mod or maybe something with a oneshot or even a 555 timer or other hardware work around depending on how important you feel it is. I use an Elecraft KPA 500 amplifier and for normal SSB operation it hasn't caused an error condition. That's not saying everyone's situation would be the same, clearly full carrier modes may be more problematic in theory however in practice IDK.
  7. G0GSR

    G0GSR Ham Member QRZ Page

    Thanks for trying.
    But this was first reported to Icom in 2016.

    It looks like the Elecraft KPA1500 actually has a user selectable delay setting to "correct" for transceivers trying to hot-switch.
    Good on them!

    I believe that the KPA500 uses a PIN switch so no arcing but still undesirable to switch on power.

  8. VE3IQL

    VE3IQL Ham Member QRZ Page

    Can anybody provide a circuit I can put together for the tx off timing other than the 100uf capacitor? That works but as mentioned, it affects my use of the antenna tuner port to give me 10 watts..
  9. G0GSR

    G0GSR Ham Member QRZ Page

    Terry, have a look on my QRZ page for my circuit.

  10. VE3IQL

    VE3IQL Ham Member QRZ Page

    Thank you Frank. You have a fascinating QRZ page.
    I found your circuit but a bit much for me to interpret.

    There is a board mentioned on the ic-7300.groups.io that I may try.
    https://www.ebay.ca/itm/274343718849?ssPageName=STRK:MEBIDX:IT&fromMakeTrack=true ..
    Unfortunately it uses relays instead of an optoisolator that I use to key my amp with now.
    I would simply use the 100uf capacitor but I use the "10Watt tune feature" a lot, and the capacitor reacts.

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