[K3CAL] Important Information about the Sunderland Repeater

[jimmy mumper]

1 I knew it sounded like p25
2. The Calvert system is 800, and there aren't any other VHF P25 systems
around the local area

On Sat, Mar 28, 2026 at 8:56 PM KB3WFV via K3CAL <k3cal at mailman.qth.net>
wrote:

>
> 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 A) Replace the outdated, discontinued amateurish radio equipment with a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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