[Hallicrafters] Piesoelectric effect case in point.

[Carl]

"Probably, replacing with another ceramic disc might have solved the 
problem."

That says it all and nothing more to up the word count is needed.

Ive also had modulation transformers talking back to me but I didnt replace 
them with a toroid version. Instead I tightened the laminations or even 
removed, cleaned and rebuilt..

Ceramic is a brittle crystalline substance, constant heating and cooling can 
create tiny fractures. In RF Ive heard transmitting ceramics sing (buzz) 
when on the way out.

Anyone who has spent enough time around tube radio repair has had a 
Centralab or other couplate talking to them. Simply a manufacturing problem 
and they didnt stick around long.

None of this equates to some of the outlandish "theories" Ive read here and 
on audiophool forums.

Ive no problem with any ideas, they can be proven or disproven and we move 
on. What gets my ire up is when someone tosses out a real humdinger and 
treats it as gospel based on lack of knowledge, education, experience, 
common sense or all the above as in the audiophool world of oxygen free AC 
line cords!

Carl
KM1H


----- Original Message ----- 
From: "Glen Zook" <gzook at yahoo.com>
To: <hallicrafters at mailman.qth.net>; "rbethman" <rbethman at comcast.net>
Cc: "Peter Bertini" <radioconnection at gmail.com>
Sent: Sunday, January 02, 2011 4:31 PM
Subject: Re: [Hallicrafters] Piesoelectric effect case in point.


There may not be any way that a ceramic disc capacitor can become a 
transducer, but I have, on very rare occasions, heard audio coming from a 
disc ceramic capacitor that has been used for coupling in an audio circuit. 
Replacing the capacitor, usually with a "poly" type, has cured this 
"problem".

I have also run into an occasional problem where, when "tapped", a disc 
ceramic capacitor did act microphonic and introduced the "sound" into the 
audio chain.  Have run into this on both transmitters and receivers.

Probably, replacing with another ceramic disc might have solved the problem. 
One that did not have whatever "defect" which caused it to act like a 
speaker.  However, when I do experience this I just replace the disc ceramic 
capacitor with a different type and go on to the next problem.

Glen, K9STH

Website:  http://k9sth.com


--- On Sun, 1/2/11, rbethman <rbethman at comcast.net> wrote:

Having just researched ceramic capacitor construction, I don't see ANY way 
that these would have the ability to become a piezo transducer, OR having 
anything to do with these old boatanchors.

You "may" want to do a bit of research also. They also manufacture "dipped 
ceramic" capacitors.



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