Michael wrote:

Hi,

I built the AN762 amp along with 6 low pass filters with parts bought from
Communication Concepts.

The amp itself (180W version) works fine and can easily produce 180W with 5W
input.

Now to the problem and question:

I wanted to put it in a good solid case with the filters, a RX/TX relay (8A
240V Omron relay also bought at CCI) a manual switch for the filters and the
filters.
I also found a good heat sink for the PA.

I connected all parts with short runs of RG-58, but a lot of the power seems
to get lost in this system. If I'm lucky I can get 100W out. Even if I
bypass the filters. Is RG58 a bad choice for the internal wirering? Is the
manual switch a bad choice?
What special things should I address for optimum perfomance?

In my case the PA is placed on the back panel direcly mounted on the heat
sink. I made a rectangular hole in the back for the PA board.
The input and output connectors are also on the back panel. The filters are
mounted at the bottom of the box and connected to a band switch mounted on
the front panel. Behind the filters and in front of the PA is the RX/TX
relay cirucuit.

73
de
Michael
OZ8AGB


Is this HF? RG-58 should be fine. RG-174 should be fine for that
matter, if this is HF or even VHF. I would suspect that you either have
one defective component, a poorly attached connector, or a damaged cable.

Assuming that it's linear you could just put 5W in, let it run into a
solid dummy load for a while, then feel around the input path for the
hot thing. If you're losing 2 watts to one component you'll be able to
feel it.

If you can you may want to feed the amp it's 5W directly and see if it
still gives 180W. If it were me and I was desperate I'd yank the amp
out of the case, make sure it was doing 180W on the bench, then put it
back in the case checking at every step. So I'd verify 180W with it
just bolted in, then verify power through the filters (accepting a bit
of loss), then verify power with the case's connectors, etc., until I
either found the problem or had my completed amp.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com