Ceramic Detector ?

Talk about anything that doesn't fit in a topic below - Also used for board announcements.
Post Reply
redbird
Posts: 136
Joined: Mon Mar 11, 2002 9:34 am

Ceramic Detector ?

Post by redbird » Tue May 02, 2006 2:11 pm

Can anyone explain what a ceramic detector is, how it works, and what can go wrong with it? As in a fm receiver.

k2hz
Posts: 150
Joined: Sun Jan 30, 2005 1:02 pm
Location: Rochester, NY

Post by k2hz » Tue May 02, 2006 8:59 pm

A FM detector circuit may use a ceramic resonator instead of a tuned LC circuit. This is particularly common in Integrated Circuit quadrature detectors. The advantage of the ceramic resonator is that it is fixed tuned as manufactured as compared to an LC circuit where the coil has to be adjusted to the proper frequency.

Not too common but not impossible for the ceramic resonator itself to fail. More common for the Integrated Circuit chip or other component to fail. In some cases the Integrated Circuit is the FM IF stage as well as the detector.

Two way repair man
Posts: 83
Joined: Mon Apr 05, 2004 12:36 pm
Location: Melbourne, FL

Ceramic resonator failures

Post by Two way repair man » Tue May 02, 2006 10:16 pm

I have seen ceramic resonator fail because of vibration (in a vehicle) or shock (the radio got dropped) or corrosion.

There is a ceramic detector but I have not found a web site stating that they are in use in two way communications. (Flat Ceramic Detectors (FCD) Technology. #1086. Flat Ceramic Detectors is a thin-film layer of polycrystalline material with high-absorption efficiency for the detection of x ray and gamma ray at ambient temperatures. Its highest resolution is in the range of 2 KeV to 1 MeV due to the direct conversion of the x-ray photons into electric charges. It has the best "stopping power" of gamma and x-ray radiation because of the high atomic numbers (Z) of its components. A filmless x-ray system is the first implementation. Under development.)

Just my two cents worth.

Bill

redbird
Posts: 136
Joined: Mon Mar 11, 2002 9:34 am

Post by redbird » Wed May 03, 2006 10:00 am

I have a portable that has a ceramic detector and the audio is distorted and sounds like the detector coil needs adjusting. Could dropping the portable cause the ceramic detector to distort the audio?

k2hz
Posts: 150
Joined: Sun Jan 30, 2005 1:02 pm
Location: Rochester, NY

Post by k2hz » Wed May 03, 2006 5:15 pm

redbird wrote:I have a portable that has a ceramic detector and the audio is distorted and sounds like the detector coil needs adjusting. Could dropping the portable cause the ceramic detector to distort the audio?
It is a possibility that the drop caused the frequency of the detector ceramic resonator to shift. Another cause could be a ceramic IF filter was damaged. If the receiver is double conversion, the 2nd LO crystal may have shifted frequency. If the audio out of the detector looks OK on a scope then it is probably an audio circuit problem.

I have only seen a ceramic resonator fail completely when dropped but I would not rule out the possibilty of mechanical shock damage causing the frequency to shift.

User avatar
wowbagger
Posts: 8
Joined: Tue Jun 21, 2005 5:44 pm
Location: Wichita, KS

Re: Ceramic resonator failures

Post by wowbagger » Thu May 04, 2006 10:25 am

Two way repair man wrote: There is a ceramic detector but I have not found a web site stating that they are in use in two way communications. (Flat Ceramic Detectors (FCD) Technology. #1086. Flat Ceramic Detectors is a thin-film layer of polycrystalline material with high-absorption efficiency for the detection of x ray and gamma ray at ambient temperatures. Its highest resolution is in the range of 2 KeV to 1 MeV due to the direct conversion of the x-ray photons into electric charges. It has the best "stopping power" of gamma and x-ray radiation because of the high atomic numbers (Z) of its components. A filmless x-ray system is the first implementation. Under development.)
Bill
Which as as much to do with the ceramic resonator used in communications as a metal detector does - which is to say, none at all.

The ceramic resonator which is used in the detector circuit acts like a tuned delay, shifting the phase of the signal presented to it by a fixed amount. This is used to create a signal 90 degrees out of phase with the incoming signal, which allows you to detect the rotation of the carrier in the I/Q plane - which is to say it allows you to detect the frequency shift.

Yes, a hard enough shock could break the device, but I would tend to think that such a shock would have done great violence to the rest of the radio.
If you have questions on the IFR COM-120[ABC] or 2975, I designed them. If you want manuals, calibration information, or pricing information, please contact Aeroflex directly.

Post Reply

Who is online

Users browsing this forum: No registered users and 2 guests