Need help with parts for new control station

[rangerfourever]

Hi guys, as mentioned under other headings, my small PD is trying to put together a control base for our secondary use simplex VHF freq. I have an XTL 5000 with desk mike and power supply setup now. Outside the building is a 40' tower with tappered pipe on top. We need to cover about 47 square miles simplex. The XTL is 50 watts out on VHF. What type of hardline and base antenna would work without breaking what limited funding we have. I am thinking a 3db stick, say by Sinclar, would be fine. Hardline does not have to be the best, as this is a very short run, maybe 100 ft. Thanks!! Chief looking for some ideas, so we can get this done this FY which ends in December.

Thanks

David P White

[RFguy]

This is a public safety system and you don't want to use the services of a professional radio shop because.....

[k2hz]

If this is a "control station", which is defined as a fixed station on the mobile channel controlling a mobile relay station, a directional antenna aimed at the mobile relay site is generally required.

In any event, the antenna gain needs to be consistent with what you specified in your ERP calculation for your frequency coordination and FCC license.

Why isn't your radio service vendor answering these questions?

[rangerfourever]

Radio shop is doing install, I just like to have some informed questions for our shop guy. The license was done and never changed since 1977, city coverage area is a whole lot bigger now. Most of you guys must not work for governments. LOL Logical thinking does not work with most public agency governing boards!!!!!

thanks for the info....radio shop will be out on Thursday

David

[k2hz]

I am attempting to understand what you are doing.

Adding a base or control station requires a license modification unless it is an additional control station and you are authorized for control stations under the "20 foot rule" and the additional station complies with this limitation.

If it is a "control station" your coverage is that of the associated mobile relay station. Increasing control station antenna height or power beyond what is needed for a quieting signal at the repeater receiver does nothing for your coverage but will increase interference you cause to co-channel users on your mobile frequency.

Any change in power or antenna height for a base station from what is specified on your license requires frequency coordination and license modification prior to any changes.

[RKG]

The original post indicates simplex use, which eliminates the possibility of classifying the station as a "control station."

Any transmitter that is not a control station attached to a fixed power source and fixed antenna is a "base" or "fixed" station, and requires its own authorization in the station license.

[RKG]

The original post indicates simplex use, which eliminates the possibility of classifying the station as a "control station."

Any transmitter that is not a control station attached to a fixed power source and fixed antenna is a "base" or "fixed" station, and requires its own authorization in the station license.

[k2hz]

This post raised red flags with me because it reminded me of this situation:

A small village PD had a control station on the county MRD repeater. It was 2 frequency with talk around which was sufficient even with the low power and directional antenna for simplex use in the village.

The chief decided he wanted a "private" channel and the ability to use it over a wide area so they got a license for a simplex channel. Then, they put the new channel in the control station in place of talk around, added a 100W amp and put up a 100' tower with a 6db omni antenna.

When they operated this on the county repeater input, it caused havoc with 2 co-channel public safety sytems 75-100 miles away.