Vertex radios not working after narrow banding.
There is a Vertex Standard "Technical Bulletin" # 201206-04 that discusses this.
Taken from a copy of this bulletin:
"Model Number
VX-160, VX-231, VX-351/354, VX-2100/2200
Symptom
Poor receive sensitivity
Description
The problem occurred when the below listed batch of filters was exposed to humid environments for an extended period of time. Phosphorus and Silver buildups would occur and cause insufficient isolation. The problem seemed to be far more exacerbated in Latin America than in North America.
The ceramic filter failure issue has been exhibited in serial number date codes from June 2006 and lasted through June, 2009. This is represented in serial numbers that begin with 6H through those that begin with 9H. It was the belief of Tokyo engineering QA teams that they can confirm the elimination of the issue by July 2009, or serial numbers beginning with 9I. VX-231 did not start until 8H, so they are limited in the number of failures that occurred."
I have also seen problems with the Vertex VX-4200 series of radios that is caused by this as well.
The fix is to replace (in the VX-4200's) CF1001 and CF1002 with new filters LTM450EW and LTM450GW respectively.
I have had lots of problems with customer service from the Big ^^ as well since they took over Vertex. My solution, buy from Harris.