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Thread: Feed back coming from tuner ?

  1. #1
    Master Navigator N8GAV's Avatar
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    Feed back coming from tuner ?

    I'm trying to figure this one out, on 10, 15, 17, meters and not on the whole band I talk and then all at once my voice comes over my tuner to where I can hear clear ? It doesn't do it all the time just every so often. New one on me, anyone know ?
    [SIGPIC] 73

  2. #2
    'Grumpy old bastid' kb2vxa's Avatar
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    How does voice come over a tuner when it has no transducer? Sorry, without an accurate description of the problem we can't come up with an accurate solution. I would think something with a speaker in it, but what?
    "New Jersey, the most American of all states. It has everything from wilderness to the Mafia. All the great things and all the worst, like Route 22."
    Jean Shepherd K2ORS (SK) & WOR radio personality

    Engaging a troll is like playing chess with a pigeon. The bird will just knock over the pieces, shit on the board, and fly away to declare victory to his friends.

    73 de Warren KB2VXA
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    Volcano Tamer PA5COR's Avatar
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    It happens.
    Once i was near our strongest Am station with a few 100 KW, a few miles away a few grass leaves were contacting a electric fence wire and the sound of the AM station could be heard.
    So something inside the tuner can rectify the modulation and swing some part in it to make it audible.
    Must say i never had any of my tuners do that to me in the 41 years i'm active.....running 10 to 1000 watts AM/SSB...
    Homebrew, Kenwood nor MFJ....

    https://www.youtube.com/watch?v=-lVGUHH9SlY
    See here some Russian idiots...
    Last edited by PA5COR; 10-03-2018 at 04:16 PM.
    "If the Republicans will stop telling lies about the Democrats, we will stop
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    Master Navigator N8GAV's Avatar
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    I wonder if it's a CB'er that lives on the next block ? He's got a tower, beam, and may running some power I'll have to keep an eye on that
    [SIGPIC] 73

  5. #5
    Volcano Tamer PA5COR's Avatar
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    If you hear your own modulation it must be from your end, though if the Cb'er uses high power, some mixing might ensue.
    Certainly if you use the bands near the 11 meter band...as you stated.
    still wondering about what would rectify the modulation and what part could cause the audio to be heard, it needs a mechanical swinging an part.
    But if a grass reed can do that, all bets are off...
    "If the Republicans will stop telling lies about the Democrats, we will stop
    telling the truth about them." - Adlai Stevenson (1900-1965)
    Im not liberal/conservative, Im anti-idiotarian.
    At some point in the last 20 years, the left moved to the center, and the right moved into a mental institution

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    Master Navigator HUGH's Avatar
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    Working in a BBC HF and MW station with a total input power of over 1.8MW threw up some interesting effects with anything large and metal on the station. You could listen to individual programs quite selectively but the best was a chain-link fence around the site (of several acres with sheep grazing) which put up quite a cacophony of audio. Incidentally a pair of headphones with a diode across the plug worked well too.

    Elimination of RF could be done by filtering without modifying anything and it's possible multiple (or non-existent) grounding may be responsible. Good luck with that one.

  7. #7
    The Fluid of Spock KD8TUT's Avatar
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    Quote Originally Posted by N8GAV View Post
    I'm trying to figure this one out, on 10, 15, 17, meters and not on the whole band I talk and then all at once my voice comes over my tuner to where I can hear clear ? It doesn't do it all the time just every so often. New one on me, anyone know ?
    I've seen this when coils vibrate at a resonant harmonic of a frequency. Usually dropping some wax onto the coil will stop the coil from vibrating and creating the sound.
    --
    So there I was, totally naked. With only a rubber hose and a stuffed animal...

  8. #8
    'Grumpy old bastid' kb2vxa's Avatar
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    Back in the day I worked in a TV shop, we used a "green stick", actually a fiberglass rod as a n insulated stethoscope to pinpoint noises in the HV cage. Garage mechanics used metal rods to pinpoint noisy lifters and such in engines. Since active tuners have high RF voltages present and are detuned by metal where it's not supposed to be I would use a fiberglass rod with one end pressed against the bone just in front of the ear canal, fiberglass and bone conduct sound much better than air. For that reason I would have someone else speak into the mic, or better yet use a test tone, or best yet give your transmitter a two tone test, a two birds with one stone approach. Do I have to tell you a dummy load is better than crapping up the band with on air tests? They are the court of last resort, if your antenna presented a 50 ohm load you wouldn't need a tuner... read on.

    One last thing, I have a bad feeling about this, the last time I heard a tuner "singing" it was internal arcing, the internal balun screaming in pain. This was surprising at first, an MFJ "3KW" tuner arcing with only 100W of AM, modulation struck the arc followed by the hiss of carrier arcing inside the balun. It was more the antenna system than the tuner, a 160M sloping open delta fed with open wire ladder line. It turned out the line was a half wave on the 75M AM Gangsta band sending the high RF voltage at the antenna feed point down to the tuner, baluns like current feed, voltage feed kills them. This is where the old Johnson Matchbox shines over today's tuners, it has a balanced output and one leg can be shorted to ground for unbalanced output, it laughs at high voltage.
    "New Jersey, the most American of all states. It has everything from wilderness to the Mafia. All the great things and all the worst, like Route 22."
    Jean Shepherd K2ORS (SK) & WOR radio personality

    Engaging a troll is like playing chess with a pigeon. The bird will just knock over the pieces, shit on the board, and fly away to declare victory to his friends.

    73 de Warren KB2VXA
    Station powered by atomic energy, operator powered by natural gas.

  9. #9
    Master Navigator N8GAV's Avatar
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    Well It's not my voice, it's a CBer ! My HF rig is off and I was sitting back in shack working on a HW 32 and I heard the guy through the tuner. Interesting
    [SIGPIC] 73

  10. #10
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    Quote Originally Posted by N8GAV View Post
    Well It's not my voice, it's a CBer ! My HF rig is off and I was sitting back in shack working on a HW 32 and I heard the guy through the tuner. Interesting
    Deja-Vu!

    Early 80's I was QRO to the point of having higher AM output than some local AM broadcast stations.

    I lived on a Cul-De-Sac and, respected my neighbors; when they had problems with my transmissions, they would stick their head out the door, call my name and let me know they were on the phone or watching T.V.

    One day, my neighbor came across the street and ask me to stop transmitting because I was tearing up everything in his house; I invited him in, told him that my equipment wasn't even turned on and, was cold to the touch.

    My neighbor then stated, "Yea, that didn't sound like your voice either and you don't call yourself 'CB-Handle'."

    Come to find out, it was my radio neighbor 2 blocks on the other side of my cross-the-street neighbor. My radio neighbor was "QRO-er" than me and had turned his 6 element Yagi in a North-West direction in line with my neighbor's house.

    I had to call him up and tell him to knock it off before James Bridgewater came knocking on both our doors wanting to know what, was going on.

    .

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