Debugging a bug - crystal controlled

[Nina]

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, and I suppose they work on the third overtone and then doubled, meaning I think the crystals are around 87MHz. The SMD ones 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 it's not from the PCB. I'll be very thankful for any help - maybe a link to similar device.
As well, I'd like to know if when I order a crystal, I have to mention it's for the 3rd overtone.
Regards,
Nina [/u]

 

[VSMVDD]

Re: Debbuging a bug - crystal controlled

does the device have a writing on it to give us a clue

or can you take photo with a camera or phone
and post it to view
:arrow:

 

[Nina]

Re: Debbuging a bug - crystal controlled

Thank you for responding, VSMVDD.
I include 2 pictures, one of the board, the second of the device I've asked about.
By the way, it uses only 3 transistors.
**broken link removed**
**broken link removed**

I'll be very thankful for any help.

 

[biff44]

Re: Debbuging a bug - crystal controlled

Four legs on a crystal--two are probably case ground. Take an ohm meter and see if two are connected internally, they would be the ground leads.

It is fairly possible that it is a saw resonator at 433 MHz (or possibly 480 MHz as stamped on the cover). Same deal, 2 of the 4 resonators would be ground, but may not be internally connected.

 

[Nina]

Re: Debbuging a bug - crystal controlled

Thank you biff44,
It confuses me very much, as it is written 480 - 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 (maibe 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...