Debugging a bug - crystal controlled

[nina.p20]

I have several UHF "bugs" and I wish to understand several things:
All the bugs I have work on the 433MHz band. SMD components.
Several use a simple metallic case crystal, U49, and several use SMD
components only , and I suppose they work on the third overtone and
then doubled, meaning I think the crystals are around 87MHz. The SMD
components have 4 "legs" - no idea which kind of crystal is this one,
or it may be even an oscillator I cannot debug it to know which kind
of device is it. I need your help, maybe someone may know this device:
4 legs - one from each side, black, about 6mmx4mm. All I could do is
to measure the frequency with a counter - at 3 legs it showed me
433.9MHz - but I'm not 100% sure the signal I read it's not from the
PCB. I'll be very thankful for any help - maybe a link to similar
device.
It confuses me very much, as it is written 480 on it - no doubt, but
it works on 433.9MHz - so it has no sense. As it uses only 3
transistors and 1 diode - which I guess it's a varicap (maybe a PIN
diode), it's a "miracle"... 2 AF transistors and one (the one which
you can see at the end of the PCB - and it's "deleted" or in any way I
cannot read what is written on it) - I suppose it's an RF amp....
It doesn't make me any sense... But I'm not a "pro" in CCOs...
Please take a look here:
http://www.petrutech.com/images/P1020054k.jpg

 

[Phil Allison]

** Groper alert !

I have several UHF "bugs" and I wish to understand several things:
All the bugs I have work on the 433MHz band. SMD components.
Several use a simple metallic case crystal, U49, and several use SMD
components only , and I suppose they work on the third overtone and
then doubled, meaning I think the crystals are around 87MHz. The SMD
components have 4 "legs" - no idea which kind of crystal is this one,
or it may be even an oscillator I cannot debug it to know which kind
of device is it. I need your help, maybe someone may know this device:
4 legs - one from each side, black, about 6mmx4mm. All I could do is
to measure the frequency with a counter - at 3 legs it showed me
433.9MHz - but I'm not 100% sure the signal I read it's not from the
PCB. I'll be very thankful for any help - maybe a link to similar
device.
It confuses me very much, as it is written 480 on it - no doubt, but
it works on 433.9MHz - so it has no sense. As it uses only 3
transistors and 1 diode - which I guess it's a varicap (maybe a PIN
diode), it's a "miracle"... 2 AF transistors and one (the one which
you can see at the end of the PCB - and it's "deleted" or in any way I
cannot read what is written on it) - I suppose it's an RF amp....
It doesn't make me any sense... But I'm not a "pro" in CCOs...
Please take a look here:
http://www.petrutech.com/images/P1020054k.jpg

** Google with " saw resonator 433.9 Mhz " or "saw oscillator 433.9 MHz "

SAW = Surface Acoustic Wave.



........ Phil