Paul,
Using one "Chassis" for full duplex may cause some problems, as mentioned in an earlier post! More than likely, you should be able to find many "Mitrek" radios for next to nothing. This way, you will be able to run separate rec. and xmitter, thus you won't have to worry too much about shielding or by-passing. (The difference is apparent, when looking at a MSR2000 base and MSR2000 rpt. The rpt. has much by-passing, yet uses the same boards for rec. and exciter.) I ran seperate Mitrek radios for several years for AirForce MARS without any particular problems. That is the machine that I used the large heatsink with. I would recommend using seperate rec. and xmitters. Regards, Tim Hardy W7TRH/AFA0TP Vashon Is. Wa. ----- Original Message ----- From: "Paul Plack" <[email protected]> To: [email protected] Sent: Monday, April 26, 2010 10:49:00 AM GMT -08:00 US/Canada Pacific Subject: Re: [Repeater-Builder] Mitreks as UHF Repeaters? Tim, My plan at this point is to convert them to full duplex, so I can use the second Mitrek to prepare a complete, plug-in, standby set of RF decks. The mods look very straightforward, but I was wondering if there were any gremlins people discovered. Your heatsink approach, however, is exactly what I was talking about. I have several very large heatsinks originally designed for use with big SCR switching circuits which look to be more than generous for a 30w PA at 100% duty cycle. My first repeater was built from a 2w Repco exciter board repurposed from RFID service. It was supposedly rated for continuous duty, but had to run very hot to dump the heat it produced through the little aluminum tab mounted to its own PC board within the case. I fashioned a new tab with a 90º twist which allows sinking the little PA to the case itself, and it never got above "warm to the touch," even after hours key-down. Guys, I appreciate all the input. 73, Paul, AE4KR ----- Original Message ----- From: [email protected] To: [email protected] Sent: Monday, April 26, 2010 10:16 AM Subject: Re: [Repeater-Builder] Mitreks as UHF Repeaters? Isn't the rpt. going to be built using (2) Mitrex, thus shielding should not be a problem. I have, in the past (with the help of a Bridgeport mill), fashioned "Larger Heatsinks", that bolt onto the orig. Mitrex heat sink....seems to dissipate heat well...
