Despite the efforts of the last several weeks. The Sunderland VHF repeater continues to  malfunction. It's persistence will require the shut down of the VHF repeater and therefore it's RF linked EchoLink. The UHF repeater in Lusby will remain on the air without a link to Sunderland.

 it appears that Sunderland VHF repeater is receiving interference with it'self or from another transmitter on the site. This interference results in a open discriminator squelch that sounds like a P25 Digital Signal. This signal can manifest it's self in multiple ways resulting in the VHF repeater re-transmitting the noise and/or multiple triggers of the courtesy tone in repeat  succession.

A key indicator of this interference is a noise level increase on stations with weak signals. Most notably those using the VHF repeater from a distance or those using low power transmitters. When this noise level increases, it is almost guaranteed that the interference will be present when the station unkeys.

The frequency of this interference varies from occasional short burst to prolonged periods of lengthy intervals.

Possible causes:

A) Inferior radio equipment with porrly designed interface hardware and wiring.
 B) A problem with the county owned CARA VHF antenna or coax.
C)  A non CARA, agency malfunctioning transmitter.

Solutions:

A) Replace the outdated, discontinued amateurish radio equipment with a commercial repeater that is designed to be in a multi transmitter site.

AND

B) Put me in direct contact with the Motorola Tech who is responsible for maintaining the Calvert County Public Safety Radio System, for on-site testing of the CARA antenna system.

Moving Forward:

The cost to replace both the VHF and UHF repeaters with VoIP connection is estimated to be $6,000.
Member approval is needed to make this purchase. The by-laws require membership to hold a vote at....

A) The next General Meeting April 9th 2026.

OR

B) At a special meeting called specifically for the discussion of and voting on the purchase of new repeaters.

C) Raise the funds for purchasing the new repeaters. Donations can be made at: https://www.k3cal.club/donate.html

So far, three members have donated a total of $ 270.00, with one of them pledging $ 150.00 per month until the new repeaters can be purchased.

Summary:

The above information is the accumulation of four years of testing, research, programing, multiple configurations, dozens of trips to the tower sites and countless hours of listening. For anyone who wishes to find an alternative to the above, they are welcomed to do so on their own. The 3.73 Gigabyte of data on a thumb drive, with all manuals, schematics, wiring diagrams, multiple Excel spreadsheets, program files, as well as all necessary programming software and cables are available for pick up.

Brian
KB3WFV

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