Marlborough East

The Marlborough East repeater site houses the 29.68 and 53.81 transmitters. It is also the former site of the 146.61 repeater, which is now located in Mendon, MA.

 


29.68 Transmitter
The 29.68 repeater operates split site, with its receiver at the MMRA Weston Site, and the transmitter here at Marlborough East. For more information about the receiver, see our page on Weston.

The 29.68 transmitter is a GE MASTR II base station. The base station includes a UHF receiver, and 100W power amplifier. The receiver picks up the incoming UHF link frequency (from the Weston site) and hands it to the 10m transmitter. The repeater shares a SCOM 7K repeater controller with the 6m transmitter

The repeater was originally installed in July, 2009 and rebuilt into a shared rack with the 6m transmitter in 2016. In the photo, the UHF link Motorola M120 link receiver is located on the right, just above the upper Mastr II. The 10m transmitter is the upper Mastr II.


53.81 Transmitter

This repeater was installed in October 1996. It has been operating nearly continuously since then.

The 53.81 repeater operates split site, with its receiver at the MMRA Marlborough West Site, and the transmitter here at Marlborough East. For more information about the receiver, see our page on Marlborough West.

In the photo, the UHF receiver and 20W exciter are housed in the lower Mastr II cabinet. The 20W output is attenuated down to 3W and sent into the final amplifier located at the top of the rack. The amp is built from a salvaged module from a broadcast television transmitter (see below).

Other things you can see in the photo is the SCOM 7K controller in the center and Astron 50A switching power supply that powers the receivers, controller, 10M transmitter and 6M exciter. The final amp is powered by a separate power supply not shown in the photo. Below the power supply on the left is the Uniden Force link radio. This provides and RF link for either repeater to either MMRA's Hub 1 at Marlborough West, or MMRA"s Hub 2 at Weston.

At the very top of the rack is a Rasperry-Pi module with FreedomPop 3G data device. This provides MMRA with internet control of the repeater. The Pi is connected to the serial port on the Vyex DAB board installed in the 7K.

The Larcan transmitter was originally part of the WTAE (TV ch. 4) transmitter in Pittsburgh. MMRA acquired several transmitter modules like this one from WTAE and other stations, and sold them as a fundraiser for the club. MMRA also kept three for club purposes, this being one of them. Although the module is capable of operating 600W continuous duty on FM, this one is running at about 350W.

 


A Little History About The Equipment At The Site



The original construction of the 6, repeater began in the summer of 1996. Bryan modified the tube power amplifier by removing a turn on the plate coil and changing the topology of the grid circuit. Additionally, the PA low pass filter section's doorknob-type capacitors needed to be changed.

<   The photo on the left shows the 6m repeater prior to November 2016. In this photo, the tube amplifier is still installed. At the time the photo was taken, it was no longer in use.

The photo on the right shows the Larcan in a separate cabinet, as it looked prior to the work down in 2016. The original Larcan construction began in October 2009 and was installed on January 30, 2010.   >



The 10M repeater was also a separate project done by WA1NVC and was housed in a third rack:



As you can see from the last photo, all these racks took up a lot of room - the site was pretty crowded.
In 2016, the tube equipment was scrapped and 10m and 6m were consolidated into one rack.



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