W2ARP Amateur Radio,

Robert Pantazes

Installation Saga of the new K2BR repeater, Aug. 2010
By Robert Pantazes, W2ARP
Southern Counties Amateur Radio Club (SCARA) had an old Motorola Micor Mobile
built and modified as a 2-meter repeater by Jack K3IHA (SK). We were having problems
with the 35-year-old Micor. The Club's Board of Directors and the Membership voted to
purchase a new repeater in June 2010.
The repeater committee decided on a Vertex/Standard repeater model VXR-7000. This
unit is a 50 watts continuous duty model with an advanced microprocessor controlled
transmitter and receiver. We would interface the new repeater with the already updated
SCOM 7K controller. The VXR-7000 has the ability to be connected to an external
controller, plus it has a built in controller as a backup. We used the ACC connector port
of the VXR-7000 to interface our SCOM 7K.
I built a cabling interface between the VXR-7000 repeater and the SCOM 7K controller.
Ed, W2KP, built a shelf to put the VXR-7000 on in the equipment rack. The VXR-7000
was ordered by Club President Bill, KC2AAY in July 2010. When it arrived from the
vendor, I set it up on my bench for testing and check out of the repeater. We found that
the vendor did not program the new repeater correctly; it would not let the TX PTT if a
signal is present at the RX. A repeater must TX and RX at the same time.
Lou, KA2NTT, contacted the vendor and had them send us the programming software
and interface cable so we could correct the error. After we received the software and cable,
we corrected the vendor's software error.
Bill, KC2AAY, Lou, KA2NTT, Ed, W2KP, Arnie, W2OB, Howard KC2TYZ and
myself then mounted the repeater and connected it to the SCOM 7K controller, duplexer
and antenna for on the air testing. The audio levels were then setup by Lou, KA2NTT
and I using a Ramsey over the air-metering monitor.
During testing we found that the unit would sometimes shut down the TX power out.
After checking the Duplexer (the unit that passes the RX and TX signal to the same
antenna), cables and antenna we concluded that we had a bad VXR-7000 repeater. We
could temporarily run the repeater into two antennas, one for RX and the other for TX.
We then contacted the vendor and found out that there is an issue with the VXR-7000
going into a Duplexer. The Vendor and Vertex knew of a modification that had to be done
to the final TX RF stage. To save us the trouble of doing the modification the vendor sent
a replacement repeater.
We did not have the time to finish the install on the first day and all agreed to let the
repeater run as a non CTCSS (tone) or Carrier Squelch repeater. We still had to wire the
CTCSS encoder into the controller (the VXR-7000 does not have CTCSS Decode
output). We received the second new repeater a week later and Lou, KA2NTT, Bill,
KC2AAY and Arnie, W2OB switched machines. The shut down problem went away
and the repeater worked to spec. We were still on Carrier Squelch operation and Lou,
KA2NTT tried to use the repeater's internal CTCSS Decode to turn on the TX with a
correct tone, but the controller would lock out the repeater. Therefore, we decided to keep
the unit on line as a Carrier Squelch Repeater.
I was recovering from shoulder surgery and when I felt better would install the CTCSS
decoder board into the SCOM 7k.
Three weeks after the start of the install of the VXR-7000, myself, John, K2JGB, and
Bill KC2AAY, did install the CTCSS board and got the repeater running as a full tone
excess (CTCSS) machine on Monday, August 9, 2010.
To all who helped out, SCARA
Thanks you for your hard work and expertise on this club project!
This article appeared in the SCARA NewsLetter and was edited by: Larry Schall,
KB2MNTitle

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Jack K3IHA SK

K2BR/R 146.745 (-) 146.2 CTCSS