My local Community Emergency Response Team (CERT) has recently obtained a UHF repeater (ICOM CY-F221S).
It has two ICOM F221S radios linked together in a nice rack mount box. It has also been set up with a remote mic and speaker off of the outputs on the chassis back panel. The CERT group is licensed for the UHF repeater frequencies and they are in the public service band. They also have a simplex VHF frequency in the PS band (old police frequency) licensed. They have a number of Motorola HT radios (CP200) that operate on the simplex VHF frequency. They are looking at obtaining additional UHF HT radios in the future but would like to be able to use the equipment they have if they can get it to work together. I am familiar enough with electronics to be able to follow directions, but not enough to design anything beyond a basic switch box. I am a network engineer professionally so I am pretty well versed in those areas, and understand logic control pretty well. I am a technician class ham, but don't know a lot about RF as I have not had that much experience in it. I would like to accomplish the following and would love to receive some guidance from someone who has the knowledge to instruct me: I would like to set up a cross band link for them from the UHF repeater, to a VHF radio: This would allow someone on the UHF side to transmit to the repeater, and also cross-band repeat to the VHF side. The VHF side would be able to transmit on the VHF simplex frequency to the cross band side, and it would repeat onto the UHF side. I realize that this would NOT provide VHF to VHF repeating, and that is okay. I want to provide a way that the cross band link can be enabled and disabled by remote DTMF tones so that the bands can be separated when desired. I already have an old Motorola Spectra police radio operating on the VHF side at the site, and it has a dedicated antenna. It puts out 110W which is way too much for what we need. I was thinking about getting an ICOM F121S radio, Astron power supply, and ICS basic controller board. Using the existing VHF antenna, I would hook up the new ICOM (50 watts or less). Now I just need to tie the ICOM repeater, controller, and new radio together into a cross band system of sorts. Am I on the right track? I need some general guidance that can tell me, try this, this, and this. Here is what equipment you could use, and here is how you could tie it together. I have the schematics for the repeater available to me. If I don't want to spend the money for a new ICOM F121S radio, then what else could I connect easily that I can program and would be able to get at a reasonable price. This is all being done as volunteer service so inexpensive is best, but I want to avoid "cheap" equipment. Thanks for any help you could provide me, 73 Bryan Carter KE7GVJ Kaysville CERT Administration
