repeater works sometimes

[alex1]

I have a simplex repeater on top of a 100 foot building, and when I transmit to the repeater to get a response, I will sometimes get a clear response, and sometimes I will get a response of static. Could it be the other radio equipment and antennas on top of the building making interference? Is the transmitter of too little quality to act as a repeater (it's a handheld radio and a repeater controller)? I know that the repeater does not have an issue with transmitting, it is an issue with receiving.

 

Here are some specs:

 

Antenna: PCTEL ASP76551

Repeater controller: Suretech Simplex Repeater Controller, SR112

Transmitter: BTECH GMRSv1

Cable used: RG58/AU

      Also, two adapters are used on the cable

[Jones]

Q-"Could it be the other radio equipment and antennas on top of the building making interference?"

 

A- Almost without question.  If there are other UHF transmitters on that building, whether ham, Police, Fire, whatever... they will wipe out your receiver if you don't have a very tight bandpass filter.

[WRAF213]

Transmitters pretty much anywhere will desensitize a Baofeng, or any radio built around RDA1846/RDA1846S regardless of how robust they claim the front-end to be. They aren't built for fixed-antenna operation to keep costs down, and the lack of receive filtering causes out-of-band signals to strongly deafen the receiver. Something like a Motorola CDM750 would be better suited to repeater operation, and some sort of filtering appropriate to the radio-frequency environment at the antenna (bandpass filters for out-of-band transmissions like FM broadcast, or cavity filters for high-RF or adjacent-channel transmissions) would greatly aid sensitivity.

 

On another note, FCC rules require repeaters to be duplex.

[kevsh]

Simplex repeaters are taboo on gmrs, and there horrible to have two way communications as you really know when it's your turn to transmit. There is very good possibility the walkie talkies is receiving rf signals from the other transmitters. These walkie talkies, and most mobile radios don't have very good selective receivers for repeater operation.

[Hans]

On another note, FCC rules require repeaters to be duplex.

 

I knew that simplex repeaters on GMRS were verboten but I couldn't find exactly where. On that link, unless I am missing something, one must click on "repeater stations" to bring up the definition. It took me a while to figure out what you were intending the reader to focus upon. Is the definition of "repeater station" the only specific prohibition, which is enough in and of itself, or is there more language in there prohibiting simplex repeaters?

 

§ 95.303 Definitions -- SEE Repeater station

[jimndfw]

This is about as close as your going to get in the rules. 

 

§95.347   Automatic control.

[WRAF213]

The rule permitting automatic control on GMRS is 95.1747, allowing automatic control ONLY for repeater stations.

 

The definition of a GMRS repeater is as follows:

A station in a fixed location used to extend the communications range of mobile stations, hand-held portable units and control stations by receiving their signals on one channel (the input channel) and simultaneously retransmitting these signals on another channel (the output channel), typically with higher transmitting power from a favorable antenna location (typically high above the surrounding terrain).

 

While "input channel" is not explicitly defined in Part 95, 95.1763 defines which channels can be used as a repeater input and which can be used as a repeater output. The only channels authorized for transmission from a repeater are the eight 462 MHz main channels, and the only channels authorized for transmissions to a repeater station are the eight 467 MHz main channels.

 

Thus, for a repeater station to operate within Part 95 requirements, it must:

• receive a signal from a 467 MHz main channel,
• retransmit the signal on a 462 MHz main channel simultaneously with the input transmission; it therefore must be a duplex repeater
• produce its own identification, unless operating under the single-license exception; some sort of control circuitry must exist for open and closed repeaters.