TMC amp minor issue
 

IMPORTANT FIX...

A few of us bought a ready made antenna amplifier from MarkUK over the past couple or so years. Generally they have worked well, but a minor error has just come to light in the construction of the amplifier.

Basically a wire link was installed which should not have been fitted, unless the intention was to supply 12v to the amp via the coax. The result has been 12v being fed down to the TMC's antenna input via the coax. The upshot of which was that the TMC's input would at times be swamped by the 12v DC, producing variable TMC reception. Mark suggests that all of his amps were built with the link in place. Another minor risk, was that if the tip of the antenna were to be grounded, it could possibly pop the fuse.

The fix is to simply open the unit up and carefully snip the link after first isolating the 12v supply.

As supplied by Mark, the amp is sleeved in heatshirink - no need to remove it completely just cut it along one edge, then when you have finished it can all go back in place. If you remove the tin plate top cover, you should be able to see a wire link marked J, as in the photo below. The link J should also be marked on the PCB as a dotted white line. Simply snip both ends of the wire as close as possible to the PCB and remove the wire.

Having just cut the link on my amp, the before and after difference is quite marked. Before it was showing around 75% signal (Primo2) and taking some minutes to grab the TMC data, now it shows well over full scale signal and picking up the TMC data set in seconds.

The result should be even better and more reliable TMC reception. Thanks to wnj516 (Nigel) for first noticing this problem after suffering diminished TMC reception as time progressed.

http://i455.photobucket.com/albums/q...Ksampphoto.jpg