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Tram D201 meter spike in ssb transmit

Discussion in 'General CB Services Discussion' started by klj2497, Dec 30, 2019.

  1. klj2497

    klj2497 Active Member

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    When i key on ssb the meter will spike and then flutter before the meter settles on zero. it appears to transmit fine after the spike and flutter. With the watt meter hooked up the output also spikes beyond 12 watts and then returns to zero when i key up. I have swapped out the v401 and v602. and v600, v601, and v502 i also turned down the mic gain and keyed the mic, but still the same. Im stumped.


     
    #1 klj2497, Dec 30, 2019
    Last edited: Dec 30, 2019

  2. Dmans

    Dmans Sr. Member

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    klj2497,
    Is the relay/mike contacts disconnecting RX before it connects TX?

    73
    David
     
  3. klj2497

    klj2497 Active Member

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    It noticed that on am it will also spike when i key. then it shows the right readings. I monitored the signal spike i could not hear any squeal or noise when it spikes I tried another microphone but no change. how can i check to see if the receive is disconnecting before the transmit connects?
     
    #3 klj2497, Dec 30, 2019
    Last edited: Dec 30, 2019
  4. klj2497

    klj2497 Active Member

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    I found the R429 s meter adjustment is not adjusting.
     
  5. Dmans

    Dmans Sr. Member

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    klj2497,
    I would do a very close visual inspection of the contacts. If I am not mistaken, the RX should disconnect a few milliseconds before the TX engages.
    This phenomena exactly like the Browning Golden Eagles that used an electrolytic capacitor (many were changed to a higher value to prolong disconnection of the RX contacts) to delay disconnecting the RX for the "Squeal/Scream etc".
    Could be your Tram has a "bent out of shape" set of contacts in the relay that is not allowing the delay in switching??

    See the link below concerning Turner microphones. At the bottom of page 8 it describes a squeal in the first portion of TX and RX. It is stating that the audio circuit must be "made" at the same time the TX is "made". Slight bending of the contacts in the microphone is the recommended cure. I would think this scenario would apply to any other microphone as well.

    http://www.cbtricks.com/mic_manuals/turner/turner_mic_wiring_book.pdf

    If there is a delay in "making" the contacts for the audio line, I could see this causing your "spike" of the meter in SSB. You wouldn't necessarily hear it and doubtful anyone else would hear it on the receiving end in SSB-but maybe in AM??

    Good Luck

    73
    David
     
  6. klj2497

    klj2497 Active Member

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    I swapped out the microphone but there was no change.
     
  7. nomadradio

    nomadradio Analog Retentive

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    Most likely needs a relay. It's a rare one, and expensive where you actually can find it. This creates an incentive to attempt "fixing" the relay.

    Never makes it better, in my experience. Once the relay's spring fingers get bent from being "adjusted" the timing will never be right.

    Barkett has it listed, near the end of this page: http://stores.goldeneagleradios.com/tram-base-radio-parts/?sort=featured&page=3

    One other possibility. If the neutralizing capacitor C706 has been tweaked to max the wattmeter reading, the final will become unstable.

    C706 is properly adjusted to prevent the final tube from oscillating, especially in sideband with no modulation. Can create quirky symptoms in AM mode.

    When it's adjusted properly, there will always be some friction on the adjustment screw. If it's been cranked so far counterclockwise that there is no friction on it, this is what happened. And if you find there is decent friction on the screw head, just return it to the position where you found it.

    If you plan to use the radio for long at all, you need a spare relay anyway even if the relay in it is still okay. They eventually wear out. And if yours has a 4-digit date code stamped on it that begins with the digits "75", "76" or "77", it's probably factory original. It's rare to see that relay last more than 40 years.

    Really rare.

    73
     
    #7 nomadradio, Dec 30, 2019
    Last edited: Dec 30, 2019
    Dmans likes this.
  8. klj2497

    klj2497 Active Member

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    Thanks Nomadradio, I checked the c706. it was almost all the way tight clockwise from the back of the chassis. so i turned it out ccw ftbc about one turn. It didnt change or stop the spike. but It did bring up the output. i have not found the date on the relay it looks like it may have been replaced. im going to swap out the relay and see what happens.
     
  9. nomadradio

    nomadradio Analog Retentive

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    Changing the relay is the one thing you can try without a soldering iron, anyway.

    73
     
  10. klj2497

    klj2497 Active Member

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    I swapped out the relay. but, no change. I noticed when i key the relay engages, then the needle spikes hesitates and then it appears to throw the needle back toward zero.
     
  11. klj2497

    klj2497 Active Member

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    i found the spike is on am also. It looks like its causing a full power spike on the watt meter.
     
    #11 klj2497, Jan 3, 2020
    Last edited: Jan 3, 2020
  12. Dmans

    Dmans Sr. Member

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    klj2497,
    For what its worth, I am still leaning towards a relay.

    73
    David
     
  13. klj2497

    klj2497 Active Member

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    Thanks Dman, I swapped out the relay, but its still spiking. Its transmitting the spike to my watt meter on ssb, and am but i do not hear anything on the monitor radio during the spike. The watt meter spikes to about 15 watts on ssb, then settles on zero. then it has good modulation. on am it swings to about 12watts and then settles on about 5watts. I can see the final tube glow blue for about a half second on ssb when it spikes
     
  14. Dmans

    Dmans Sr. Member

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    klj2497,
    Do you have another tube to swap into the final position?

    73
    David
     
  15. klj2497

    klj2497 Active Member

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    Thanks Dmans , I swapped out the final tube it still spikes on keyup so i put the newer one back in. i also checked the rf driver.
     

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