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 Post subject: Tube Making Clinking Sound
PostPosted: Jun Sun 16, 2019 4:05 am 
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Joined: Oct Wed 04, 2017 12:27 am
Posts: 131
I have a Sylvania 12SQ7 tube which makes continual clinking noises while the radio in which it is installed operates. It seems like the incoming signal strength modulates this noise. The clinking is audible when the radio is playing at normal volume. My tube tester didn't reveal any obvious causes for this anomaly. Has anybody ever had a tube like this? I'm not currently using it but was wondering if it just needs to be trashed?


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 Post subject: Re: Tube Making Clinking Sound
PostPosted: Jun Sun 16, 2019 7:53 am 
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Joined: Oct Mon 02, 2017 8:53 am
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Location: Panama City, FL 32401
I used to have a Drake transceiver that would do that as the tubes warmed up. It sounded like a "ding". I wouldn't worry as long as it's operating properly.


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 Post subject: Re: Tube Making Clinking Sound
PostPosted: Jun Sun 16, 2019 12:28 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 5190
Location: Sunbury, Ohio 43074
[quoteThe clinking is audible when the radio is playing at normal volume.[/quote]
audible from where? In the room, or with your ear near the tube? If you can't hear it while doing normal listening, I'd just ignore it. Otherwise, replace the tube, even though this noise is probably not having any effect on the tube functioning. But if it's annoying, new tube.... otherwise keep it.

Make sure it's the tube, not some loose screw or washer nearby

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 Post subject: Re: Tube Making Clinking Sound
PostPosted: Jun Mon 17, 2019 2:50 am 
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Joined: Oct Wed 04, 2017 12:27 am
Posts: 131
I might just keep using it because otherwise it is a real good tube. My 811A transmitting tubes make that sound while they warm up, but I had never heard little tubes do that. Thanks for the input.


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 Post subject: Re: Tube Making Clinking Sound
PostPosted: Jun Mon 17, 2019 12:55 pm 
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Joined: Jun Fri 19, 2009 6:34 pm
Posts: 8840
Location: Long Island
What is clinking? Is the sound coming from the speaker in the radio, or is the tube itself making the sound? It is probably harmless, but annoying so you’d want to dump the tube either way.

If it’s in the audio and the msbehavior tends to get worse as the radio plays, it’s probably microphonism. This is a loose element in a tube which vibrates or moves, changing the tube’s electrical characteristics usually in response to vibration from the speaker. You can sometimed (but not always) find the problem by tapping on the tube while testing it. Some tube testers had headphone jacks so you could listen for such noises when tapping the tube.

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 Post subject: Re: Tube Making Clinking Sound
PostPosted: Jun Tue 18, 2019 4:11 pm 
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Joined: Jul Fri 18, 2008 10:02 am
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Location: near ST Louis Mo 62002
Tube_Enthusiast wrote:
I might just keep using it because otherwise it is a real good tube. My 811A transmitting tubes make that sound while they warm up, but I had never heard little tubes do that. Thanks for the input.



Being a transmitter tube i wouldn't worry , most likely it is the filament expanding when heating up making the noise . I heard noises like what you are describing in a lot of modulator tubes in ships radar when replacing them . Four amps of current at 6.3 volt will cause a lot of expansion .

https://frank.pocnet.net/sheets/084/8/811.pdf

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 Post subject: Re: Tube Making Clinking Sound
PostPosted: Jun Tue 18, 2019 5:24 pm 
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Joined: Oct Wed 04, 2017 12:27 am
Posts: 131
The sound definitely originates in the 12SQ7 tube because it travels with the tube when installed in a different radio. It's not being heard through the speaker. I listened to it yesterday for quite awhile and it struck me that a certain frequency from the speaker was causing the tube to sing somehow. I don't know if one of the tube's elements is resonating or if it could be the metal envelope?


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 Post subject: Re: Tube Making Clinking Sound
PostPosted: Jun Tue 18, 2019 9:17 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11737
Location: Powell River BC Canada
Hook up a 6 volt battery to pins 7 and 8 and try orienting the tube in various positions.

Is it glass or metal, and does it clink in a tube tester, on any of the three tests.

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VE7ASO VE7ZSO
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