From: "David C. Donley" Newsgroups: rec.radio.amateur.equipment > C5608 mods It is *easy* to destroy your radio while performing the procedures described within this document. It is also possible to destroy your radio using the newfound capibilities given to you by these procedures. It is also possible that the FCC and/or other amateur and professional radio operators will destroy your radio if they catch you transmitting out of band. You are incurring a legal risk by performing the modifications described herin. I am not responsible for anything that may happen to you or your property if you do any of this. Standard C5608 mods: 800Mhz receive: If you can get the Standard to read 800Mhz by holding the func button and pressing up arrow (on the radio itself) you do not need to add any resisters or anything. But you do need to add an 800 Mhz plug. I got my plug on a cord by buying a 3ft TNC externderizer for $5 and cutting it in half. If you live in an area where surplus stuff is available, you can do much better pricewise. Please only listen to the public service communications in the 800Mhz band. Intercepting radio cellular telephone communications is illegal even though they intrude on your property and give you brain cancer. Remove the black disc off the back of the radio, insert a piece of RG58 coax, and solder the center of the coax to the same PCB land as the center of the really tiny piece of coax already in the 440Mhz RF section, and the braid of the coax to the big empty untinned land on the other side of the first land. The location to solder this stuff is right next to the round RF amp with four radially protrouding pins, if that helps you locate it any better. Secure the cable to the case somehow (wireties?) so it won't shread your radio when you yank on it. Back of Radio (Heatsink) Bottom ! ! ! ! ! ! ! ! ! -O- ! ! ! ! ! --- ! [XXX] [YYY] [ZZ] /\/\/\/\/\/\/\/\/\/\ ! !------------------------------------------------------------- ! ! Lots of neat stuff. ~20 P.P.I. (Pots Per Inch) ! ! The square thing is a big electrolytic capacitor, the /\/\/\/\/ is the coax that is already there, and you should solder your shield to XXX and your center cond. to YYY. Your RG58 should come in directly on top of the big electrolytic capacitor. You would be insane to attempt this without unscrewing the red and black +12V DC power wires. You would be insane to attempt this anyway as I have and I now know how poorly it works. If you can't get the radio to read 800Mhz, remove the 1/8watt zero ohm resistor that is the third one counting from the + symbol on the side of the CPU board pointing into the radio. On the other side of the CPU board, this "resistor" is labled 'G'. If you don't know which board is the CPU board, definatly don't do this mod. To get to the CPU board, remove the top and bottom panels of the radio, and snap off the plastic side panels. This will allow you to access the screws that hold the front panel on. To avoid damaging the front panel, begin your snap-off attempts at the rear of the radio, by the heatsink. The side panels fit under the edge of the front panel and it will be necessicary to slide them towards the back of the radio to r remove them once they are partially snapped loose. The 800Mhz receive on the Standard is incredibly insensitive compared to a scanner. If you have any other way of receiving 800Mhz, it will be a waste of time for you to do this mod. BTW: Press Func+Down to get out of 800Mhz mode. Standard 350Mhz receive: Remove the #2 zero ohm jumper (also labeled E on the backside of the CPU board) There doesn't appear to be an antenna mod for this. Sensitivity is so bad it leads me to believe that the reason why this is disabled is because the RF circuitry is not implemented. This is turned on and off the same way as the 800Mhz except the 2M band must be active instead of the 70cm band. The 440Mhz band will tune down to 350Mhz so this mod is even less useful than I could have possibly suspected. It doesn't seem to be possible to switch to or from 800 or 350Mhz from the remote microphone. Out-of-band transmit: Remove the two surface-mount chip resisters on the hard-to-get-to side of the CPU board labled "D" and "H". The "D" resister controls VHF transmit, and the "H" one controls UHF transmit. Please make a diagram of where all the plugs plug back in when you take the front panel assembly off. There are a few 2 pin connectors that differ only by the color of their wires. Expect transmitting from 130-155Mhz on VHF, 400-469.995 on UHF. Please note that the Standard C5608 mobile is not appoved for transmitions outside of the Amateur band. Such transmitions are illegal even if you do have the proper commercial license. If you want to run it into a dummy load and use the harmonics to interfere with some wierd circuit you're building, then no problem, have a ball. To manually switch between AM/FM demod on the VHF band, press Func+Sub. Again, this cannot be performed from the Mic. It defaults to AM in the aircraft freq range, so this shouldn't be so bad. Repeater mode is enabled by pressing the 144 and 440 band buttons simultainiously. Cannot be performed from the mic. To prevent the radio from repeating in both directions, set the TSQ and CSQ to bizzare values on the band you don't want to be retransmitted and set the repeater offset to some other wierd freq that is hardly ever used. KD6ACL David Donley ============================================================================== Note: I haven't tried or verified this, proceed at your own risk. And DO NOT transmit outside of legal bands! WA2ISE /EX