Touch Sensitive Crystal?? That's a new one on me.

[Mitch]

I was having a play with my President Jackson earlier, when it was quiet, and I noticed a little bit of a buzz on the FM TX audio, a bit like a like a raspy mains hum, but less on UK band. I was transmitting into a dummy load and listening on another radio connected to a dummy load. I took the cover off to see if anything was loose and when I touched the mixer crystal (14.550 Mhz) the noise stopped and the frequency dropped about 1khz (on RX & TX). I tried to ground the crystal on the nearest can and the frequency dropped even more, 1.5khz, and no noise. No other crystal is like it at all, so I'm guessing this isn't normal. I've not had many Uniden radios though. This one is a PB-042AC board made in Taiwan, 5 band black front 1988 ish fyi.

Is this a crystal fault or some other component failure? If I need a new crystal are they still available? I've had this rig about a year and a half but not noticed this problem before, the noise is pretty quiet and not very noticable, so not that obvious, but the crystal instability worries me a little. I've not heard of this happening before I so don't know if it's a common fault or not, it's usually the caps that fail isn't it. It's always needed a bit of warm up time from first power on, but normally settles after 10-15 minutes or so, which I thought was normal for a Uniden rig.

[Piggly]

Crystal cans are often grounded for exactly this reason...it isn't a fault per se but is more an indication of a slapdash approach to construction quality.
Get that can grounded nicely and trim the frequency back to nominal and everything should be lovely.

[Mitch]

I have seen other radios with the crystals soldered to tuning cans but it doesn't seem very common at all, I thought I might damage the crystal with heat if I did that though, the radio is rather sensitive to temperature changes anyway, hotter is lower frequency, colder is higher, it can change by a couple of hundred hertz when the radio's hot from a waffle (a Uniden 'thing'?). TBH I was more concerned about the radio's future reliability, but I may have found someone with a spare so hopefully I'll have that soon, and I'll swap it out. I know these radios drift, at least that's what I'm told, and some are worse than others so it wasn't a surprise, but I'd never seen this type of fault before, good job I don't run it mobile.

I know it's an old rig but I like it and want to keep it in working order, the crystal may have failed over time or been poorly made in the first place, and it is only a mass produced CB, I suppose it's done well to last this long.