On 30/01/2014, at 2:18 AM, Chris Trask wrote:
But my feedline I use is a run of Cat 5 ethernet cable, with one pair carrying the signal and the
other 3 pairs sharing the +V and 0V load. So I need to reconfigure the amplifier's T6 output
transformer for separate power feed, and balanced 100 ohm coming out.
It's actually fairly simple, and can be accomplished with a few modifications. First, break the connection between T6 and C20, then connect your power line to C6, Q6, etc. to complete the supply connection. Done.
Looking at the output side of T6, break all of the shown connections. The upper terminal of the upper winding is your + output, and the lower end of the lower winding is your - output. Connect the lower end of the upper winging and the upper end of the lower winding to ground. Done.
The collectors of Q3 and Q4 will now see load impedances of 200 ohms instead of the original 400 ohms, so the power gain will be reduced by 6dB.
Thanks Chris!
Hopefully the 6dB reduction won't be too much of a penalty. I would have to go to a different design for T6 to get the gain back?
Cheers,
Andy
ZL3AG
