One of my friends recently asked me about a 6 meter Maxtrac on Ebay. After reading the description from the seller, I recommended he not buy one. The dead give away is his disclaimer about the receiver sensitivity. If you don’t have adequate test equipment to actually measure it, then it is not properly modified. If it is modified and some modifications are not easily undone, it cannot be easily returned back to 42-50 mhz. To get the full receiver sensitivity on 52/53 mhz, the coils in the RX must be retuned with non-ferrous screws (brass or aluminum). Also the RX and TX VCO coils have to be retuned to lock up to 54 mhz.
To get good power output on 6 with the least current draw, the PA board requires removal of 1 turn on several coils and shortening of a “hairpin” coil. Some hacks spread the coils and flow solder on the hairpin. It isn’t enough in my opinion to do it properly. A little known fact is the Maxtrac power control circuit has a timer. When the transmitter is keyed, the microprocessor slowly lowers power over time to 0 watts out. When you unkey, the timer reverses and counts back up at the same rate. Get in a qso of several minutes and sooner or later the transmitter power will go to 0 and you will have wait for the timer to count back upwards to get power out. When you transmit the CPU knows to start counting back down so you cannot get around this unless you modify the radio. The logic board can be modified for manual power control by cutting a trace or two and adding a pot to manually set the power output. At 30 watts a qso soon has the PA hot enough to cook on so running 50-60 watts is out of the question. This is all documented on Repeater-builder site.
I am the author of a paper floating around on the internet for modifying the Titan’s. They are somewhat similar in mods done to the Maxtrac radios with the receiver front end coils requiring non ferrous screws inserted, the VCO to be retuned to lock on the new range, and spreading of coils in the transmitter PA. It can be downloaded at hamfiles.co.uk. The Syntech II Midlands are some of the easiest to convert to 6 meters and require no hardware modifications to work if the CWB firmware is loaded.