High pitch whine???

Sounds like the idiot that peaked your radio did not know what here was doing, It sound like he removed a choke from the radio when he tweaked it, You really have to be careful these cb radio tech's, alot of them are wheel polishers that find out its easier to get your money claiming to be a radio guy. I would suggest that you take your radio to a real tech and get the choke put back in it.

The whineing after a tune would suggest that it may be getting into your radio thru the antenna if thats the case the filter being suggested on other posts here will not work because the filter in the power wire is removing ac from the dc line not filtering the rf. so if it is still there after you buy the dc filter have the choke put back in it des not hinder the performance.

 

Per the OP description its alternator whine and I wouldn't look any where outside of "grounding"
"In-line" filters aren't worth the money you pay.
Everything that has a fan or runs a "Duty Cycle" will cause some amount of RF interference(noise,static etc) on "tuned" radios,they are no longer operating under spec limitations With the majority of todays trucks having an average of 9 ECM's its virtually futile to find "perfection"

 

Glad it worked out. It may have been a dirty connection. Everything has to be clean and tight... Good Luck