DC Harris - I have to offer you some different advice than everyone else, so far, has suggested. My advice is based on past history, as well as your actual monitoring location.
First, I have your location is being near Hwy 21, in the northeast corner of Fairfield County. Is that correct ?
Basically, if you are anywhere in Fairfield County, unless you are using a directional antenna pointed to the north, you should have some problems with monitoring the Charlotte-Mecklenberg system. Richland County and the state Palnet system have three sites in your area - Blythewood being the closest. Between the three sites, about 20 of the 28 frequencies in use on the C-M system are also in use at the 3 sites.
Depending on the amount of traffic on those 3 sites, you would have a fair probability of voice comms on the C-M system being covered up by the 3 sites. Your 396 will still trunktrack the C-M system - if the control frequency isn't being interfered with - but once the scanner switches to the assigned voice frequency, the stronger signals from a local site using the same frequency will cover the C-M comms.
Also, while it cannot hurt to try, the response of the common hobby discones (I use 4) drops off beyond 500 Mhz, despite the claims to be useful through 1,000 MHz. And, if a quality feedline is not used, add even more signal loss to the equation.
Now, there's another reason why I'm discouraging an emphasis on the C-M system, based on your particular question regarding Lancaster County.
I live in Indian Land, just off Hwy 521, and midway between Hwy 160 and Hwy 75. My home is right under the flightpath used by the Med Center Air crews going between CMC Main and Springs Memorial Hospitals. To my best recollection, I have never had an occasion - been here 10 years - when one of the helos was transiting my area that I did not hear comms on 155.325 Mhz.
Depending on how far into the request for flight service they are when you start monitoring, you will hear on 155.325:
- the alerts to advise the crew they are either on stand-by, or have a request to fly (the pilot makes the final determination of whether to fly or not, unless the request is cancelled)
- basic information about the nature of the flight request (MVA, gun shot, burn victim, etc) and / or patient (weight, condition, meds, intubated ?, etc)
- the location of the landing zone or medical facility, as well as any on-location frequencies and P-L tones (Med Center Air uses of the Wulfsberg numberign system for its P-L tones
- while enroute, flightwatch generally only requests position reports from the helos if the requesting agency asks for an update
- if the helo is going to Springs Memorial for a patient pick-up from inside the facility, a county EMS unit is always on-hand to roll the patient to the helo. Lancaster city fire is also on-hand when the hospital helipad is used
- when the helo is returning to CMC with a patient on-board, you'll hear the crew request a doctor to come to the radio for a report. The report will give you a idea of the nature of the incident, as well as the age and condition of the patient on-board. The crew will also indicate how far away from CMC they are - in "minutes."
Again, I have to emphasize that I am referring to CMC comms and Lancaster County. In Mecklenberg County, and neighboring counties where the C-M system is branching out, the C-M trunked system may be the appropriate way to monitoring Med Center Air.
You may also, on occasion, hear low-power Lancaster Co EMS communications on CMC's 155.325 / 91.5 channel. The LCEMS has had the frequency programmed in their radios for as long as I've lived here ... it's their channel 6.
Med Center Air is not the only medical air transport serving Lancaster County. LifeNet, which was previously the separate LifeReach and CareForce helo services out of Columbia, handle a fair number of calls in the county ... particularly the area south of Hwy 9. They are also the go-to service when Med Center Air is unavailable, or weather minimums prevent flying in the Charlotte area. Palnet is the primary comm system for the LifeNet helo-flightwatch communications.
When both Med Center Air and LifeNet are reponding to a location in Lancaster County, also monitor 123.025 MHz ... the pilots will often coordinate their landings and take-offs with each other.
If a Med Center Air helo transports to the Columbia hospitals, also monitor 155.340 and 123.050. The first frequency is for emergency room contacts, and the second is to pass along flightwatch information and requests for flight support.