My apologies, I'm attempting to listen to 700mhz P25 freqs, not VHF utilizing the 436HP.
That's better!
In theory, it should work better with the Laird antenna but factors such as the site being simulcast can make it hard.
I've seen several users get better reception from simulcast sites by using the factory antenna if the signal strength is good enough to get inside your car. The stock antenna can help by reducing unwanted towers signals from hitting your radio. Being mobile though, this trick may not work as signal levels will be constantly changing.
There is also the chance that an external antenna can bring in too much signal and cause overload in the radio. This can be true with some but Uniden's seem to handle powerful nearby signals pretty well and don't overload easily.
Unfortunately, about all you can do is try the antennas you have and form your own opinion which one is best. Being mobile though may show one antenna works better than the other but a mile down the road and the other may work better. It can get tricky finding one solution that works throughout your drive.
One thing you can try is changing the Decode settings to Manual for each site you monitor. You cannot do this in the HP-1 but can in the 436HP.
That may be enough to clear up your reception as Auto mode does not always work very well, especially when monitoring simulcast sites or when mobile and signal levels are fluctuating as you drive for both, simulcast and regular sites. If manual decode settings are what you are after, the 436HP is the radio you want.
Good luck getting it cleared up!
