GR300 Repeater Chassis Overview

[@Subgunman]

There was also the Maxtrac based repeater called a Desktrac which utilized two Maxtrac mobiles and a proprietary repeater controller. These repeaters were useable as a desktop or wall mount configuration. No morse ID provisions however there were optional boards for remote use via DC or Tone control. Power supply utilized a unique boost - buck supply to get the necessary voltage and amperage needed for the mobiles. Power supply was capable of battery backup with charge capability. Duplexer was an external device. Radios were equipped with non standard firmware so easy swap out was a bit awkward if not impossible.

[@kelvinmahoney9323]

How did you program the I20r ? I have this exact setup and I cannot get the RSS to start on my machine running DOS. Any tips or tricks ??

[@eduardojacome9783]

Hola saludos señor. Buen video. Por favor puedes hacer un video de : "Como programar el I20R " Nadie tiene ese video y ayudarías a muchas personas. Gracias y muchos saludos señor....!

[@2012neely]

Nice, Video! I have a Gr300 with 2 GM300 radios.... Both GM300 are not working correctly so i need replacements! I do not want to use GM300, can i use anything other than GM300 and M120 can i use a different maxtrac?

[@Subgunman]

You can as long as your radios have the 16 pin connectors on the back. Make note as to how the original radios were programmed and which pins are used as well as how they are programmed. Some individuals have used the SM series of mobiles but the radio used for transmit cannot dissipate the heat properly if used full power and greater than a 20% transmit time. Fans will not help. These portable repeaters will not work well in a high RF environment so don't expect to place it in service in a site that is inner city and in close proximity with other transmitters. If there is no choice the repeater will need to be placed in a well shielded cabinet, properly grounded, utilize only a FULL size six cavity duplexer, my preference is Cellwave, excellent quality. You will also need a circulator in line between the transmitter and duplexer to prevent RF mitigating back in through the duplexer and causing harmonics within your transmit radio that can interfere with other repeaters. If you have receiver problems an additional filter can be place between the duplexer and receiver that can notch out everything except for your receive frequency. DCI makes an excellent filter for this purpose.

[@morris5368able]

I want to make a mobile repeater out of two kenwood tk-760hg-1 radios but I can't find any instructions anywhere to do that . Do you know how to make the cable to link these together?

[@Subgunman]

A good starting point is to obtain the service manual and read it front to back. It will outline accessory ports within the radio that you can utilize for RX audio, TX audio, COR and PTT lines. There are points within the radio that will provide you with discriminator audio, audio that is unprocessed and will pass low frequency audio tones utilized for restricting usage to 'authorized' users. Most amateur repeaters utilize only CTCSS but there are many repeaters out there that also use DCS and a few with P25 which is an open protocol and being an open protocol IS legal for ham use.

[@ud6asv]

Hi good video! Do you have manual for i20r?

[@taboracek007]

I hate to say that, but please get some decent lights, otherwise I find your content very educative

[@taboracek007]

+Kenneth Finnegan It's probably exposure and white balance then. The intro image seems alright

[@rpsmith]

Why would anyone who is allowed to run wideband radios opt for inferior narrow band radios?

[@KennethFinnegan]

You got me. I was only running narrowband on them because I had to.