Repeaters

We maintain an amateur radio repeater operating on the 2-meter band on the NIH Clinical Center (building 10).  It is openly accessible, but may be sequestered during drills, safety, and emergency operations.  Our 70-centimeter band repeater was decommissioned in 2014, but we have been granted access to a local 70-centimeter repeater that is also openly accessible and maintained by a member of our NIH community. See details below. EchoLink connectivity is provided on the 2-meter repeater to facilitate participation from members who live outside of the immediate area.  Notice that anyone can participate on our Monday night radio net using any of these three resources.
2 meter FM Repeater
    144.69 MHz input / 145.29 MHz output
    PL5A (156.7 Hz) encoding is required for access. This feature is activated and deactivated at the discretion of the control operator to reduce seasonal radio interference problems.
 
70 cm FM Repeater
    444.025 MHz input / 449.025 MHz output.
    PL5A (156.7 Hz) encoding is required for access. Our tests have shown good HT coverage on the Bethesda campus and to fixed/mobile stations in the Gaithersburg area.

EchoLink
    We are worldwide-accessible via K3YGG-R in your EchoLink client (for information about EchoLink, the amateur-radio Internet audio streaming service, see http://www.echolink.org/)


Some Remarkable Historical Facts

Our club member and historian, Bill Hook, W3QBC, provided some interesting historical facts about our repeater. Reproduced verbatim from en email communication of April 6, 2016:

Walter and Al,

Thank you for responding to the queries about the K3YGG repeater. I expect that your replies will provide sufficient information to satisfy the needs of those who contacted you. Here is some additional information that may be of use  in the future. You have my permission to forward this message to whomever you think may be interested
 

The K3YGG repeater went on-the-air in the summer of 1980.  At an earlier club meeting  an understanding was achieved among those attending that in accordance with the request of K3YGG Trustee Bob Balcom, W3PZK, NO CLUB FUNDS ARE TO BE USED TO SUPPORT A REPEATER,  The repeater units were to be configured, operated and maintained by a few members having an interest in and knowledge of the technology involved. Our repeater system initially used surplus Motorola vacuum tube equipment already in place at the Building 10 site. I put this on the ham frequency of 145.290 MHz as a FM simplex base station. The results on simplex were sufficiently encouraging to suggest that we reconfigure the station to operate as a repeater.  A coordinated frequency pair of 144.690/145.290 MHz was obtained from T-MARC, a   crude controller was constructed with a mechanical code wheel for ID and a mechanical carrier-operated relay (COR) for PTT. Since then, all this has been replaced with solid-state equipment.  Updated interim replacements over the years have  included, in addition to the presently used equipment, a GE receiver (not very good for repeater use) two GE paging transmitters (both eventually failed) and a RC-85 repeater controller (also failed). All of which were obtained at no cost to the Club. K3YGG/R has been  independently funded and operated since its activation. I hope we can keep it so.

To clarify, the  NIH Radio Amateur Club is not a repeater group. It is a club with a repeater. The present repeater system (Motorola SpectraTac receiver, Motorola MSR-2000 transmitter, 8 cavity filters, 4 antennas with low-loss coax feed lines, and a CAT-200B controller have been obtained as individual units  from sources  other than NLM, NIHRAC or the Club's sponsor..  Our sources have included federal surplus, purchases with cash donations from private individuals, and other (unnamed) sources.

The original uses for the repeater were to provide a Bldg. 10  roof-top transmit and receive site for Amateur Radio operators participating in: 1) NIH Emergency Preparedness activities,  2) QSOs among members and with others, 3) a  club 2m net (still meets weekly)  4)  providing assistance to help with the communication needs of the Bethesda Campus Disaster Medical Assistance Team (DMAT) when on deployment. (The DMAT has apparently been replaced by PHS call-up teams) and 5) occasionally as Unit 48 of the Maryland Emergency Management Agency. (MEMA is not presently known to be active on the 2 m ham band.)   We have also used K3YGG/R to support local events, e.g., the Bethesda YMCA Turkey Chase Thanksgiving Day Foot Race and Walk when it  passed through the NIH campus.

Amateur Radio VHF and UHF FM repeater activity in the DC area seems to have  declined markedly in recent years. This may be a result of advances in technology available to almost all persons. There is the ubiquity of computers and the Internet, cellular telephones and trunked  business and government radio systems useable by individuals and employees of federal, state, and business organizations. This has likely resulted in a decrease in the number of requests to NIHRAC for communications support. For example, NIH has provided  a large number of Motorola digital trunked handheld transceivers to employees involved with emergency medical care during training exercises and emergencies. Our analog repeater technology of the 1950's and '60s  is not very impressive today.

Please note that our repeater is a single-site installation unlike some local repeaters with wider coverage. These may have one or more remote receive sites. Be aware that our affiliated 70 cm backup repeater is a dual-site machine.

If the present K3YGG 2m repeater appears to be inadequate for some particular task let's find out why and document what needs to done to improve its performance. We have to think about antennas, feed lines, cavity filters and other things that that may affect its receiver's sensitivity. For example, we have to make certain the repeater transmitter is not desensitizing the repeater receiver. These are problems that replacing the repeater with a new box may not solve.  There is a lot of stuff that can affect repeater performance besides the transmitter and receiver.

Keep in mind that all our repeater equipment will  be moved to a new location during  the renovation of the Bldg. 10, 14th floor mezzanine (attic). This will likely begin within the next two years. I hope to be available to see what happens.

73...Bill, w3qbc
K3YGG/R co-founder, control operator, repeater mechanic and T-MARC. representative

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