Lost Lower frequencies when hard wired???

[Anand]

Hey all... I've had my Uniden BCT-8 mounted to the side of the center console in my car for a few months now, always just plugged into the cigarette lighter. A couple weeks ago I swapped out the crappy Uniden window suction cup antenna for a RS Glass mount (yes yes, I know, everyone hates the glass mounts). This gave me "decent" coverage for Maryland State Police (39Mhz) and great coverage for MTAP (455Mhz) and for the county police (850Mhz Trunked)... Although MSP was never "super clear" I could pick it up from a decent distance.

Last night I finally remounted the scanner "properly" in a DIN cutout in the dash (swapped out factory double DIN radio for a single DIN, and put the scanner below it). And I hardwired the BCT-8 using its supplied harness to the + and - coming into the cigarette lighter (figured it worked great plugged in, why not hardwire directly to the same source).

Unfortunately, while the 450 and 850 signals come in clearer and stronger now, I seem to have lost all my ~39Mhz!!! I get NOTHING on any of the MSP frequencies any more. The scanner has moved about 10" higher into the dash, but the antenna cabling still follows the same path as before. The only thing I can think of is to use a true chassis ground instead of tapping into the cig. lighter's ground wire (I assumed it would be fine as thats what it used when it was plugged in!).

Any other ideas? (Besides get a new antenna) One of the reasons I mounted the scanner was to take a drive down to TN this weekend, where, coincidentally, THP uses 42Mhz, which at this point, seems like I won't be hearing anything!

Thanks!

 

[fineshot1]

If what you stated is true it should not have made any difference. You might want to check the antenna cable connector going into the back of the scanner. Its possible it may have an intermittant problem associated with the low band frequency range. You may just want to put a new one on. I am assuming you used a crimp on BNC???

 

[Anand]

I am assuming you used a crimp on BNC???

It came with a BNC already on it... I am gonna change the grounding point tonight and see if it changes anything

 

[Anand]

Okay, so another anomaly that I noticed tonite on my way home... Unfortunately I didn't have time to disassemble the dash and change the ground wire... However... I have the Ext. Speaker output out of the scanner wired into the Aux-In on the headunit... If the headunit ISN'T on "aux-in" (i.e. if I am listening to AM/FM radio or a CD) the scanner picks up all the ~39Mhz frequencies just fine... As soon as I switch it to Aux-In, it looses them (I can see this as it will be scanning and stop on 39.XXXX often, until I switch the headunit to the Aux. mode)...

Any ideas as to what would cause something weird like this?! I am going to try to grab an external speaker from Radio Shack tomorrow on my way back over to my shop and see if that solves the issue.