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Thread: Dc volts on aerial socket

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  1. #1

    Default Dc volts on aerial socket

    Hi,
    Ft897d which i thought i would connect to my Clansman atu tuning unit...all works fine ..but on switching off the radio the meter on the atu

    (which will only respond with a clansman radio 320 or 321 radio) flicks hard over full scale for a second same on switching set on.....
    with the clansman radios connected they send a dc voltage to the meter circuit so that it reads power out/tuning.....
    but why is there a dc voltage on the 897d aerial socket when it being switched off/on ???????and it must be a fair voltage to give a hard over with the needle.....sorry bit long winded but it puzzles me somewhat
    thanks Jim g4rek




















    9

  2. #2
    Join Date
    Jan 2002
    Location
    harms way
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    13,615

    Default

    I wonder if some cap in the yazoo is discharging via the socket on shutrdown?

  3. #3

    Default

    Hi
    Do not know but it does it on switch on as well......think i will put my ft 847 in its place and see what happens on switch on /switch off.....
    do not like the way the meter slams over full scale for a second........
    Jim...........

  4. #4

    Default

    A lot of rigs will put a DC "wetting current" on the tr relays to keep the contacts clean, two of my rigs do it, however, there is usually a blocking cap in there some where. Check the schematic.

    73 m/4

  5. #5

    Default

    Quote Originally Posted by AB9LZ View Post
    A lot of rigs will put a DC "wetting current" on the tr relays to keep the contacts clean, two of my rigs do it, however, there is usually a blocking cap in there some where. Check the schematic.

    73 m/4
    Have put my FT847 in line and there is not any needle kick at all now........be interesting if a ft897d owner could put dc volt meter across the hf socket and see if there is a brief needle movement on switch/switch off ,,,to be safe rf control at minimum setting and radio set to 7 megs band........ Jim g4rek

  6. #6
    Join Date
    May 2007
    Location
    Bethany, OK
    Posts
    783

    Default

    My assumption would be it's something to do with the ATAS-120 tuning circuit. When tuning it will put certain DC voltages on the antenna jack to control the ATAS. Of course I don't know why it would do so at power on/off...

    I have an 857D, same guts as the 897D, and mine does very briefly blip a multimeter when I turn it on/off. It's hard to get an accurate reading as the voltage is very brief and my digital meter doesn't register quickly enough. Most times it's only a few millivolts but on occasion I see 2-3V.

  7. #7

    Default

    Right thanks that sounds as though your is behaving same as mine, as you say its so brief difficult to get a reading.......would not have normally noticed it but connected to the Clansman atu it kicks the meter hard across very briefly
    thanks for you help
    regards Jim

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