On Mon, 30 Mar 2009 16:59:11 +0100, "TonyL"
wrote:

Since my last post I tried reducing the HF phase shift by simply inserting a
single 33 ohm resistor directly in series with the LM388 output. This
amounts to the same solution that Don offered...that of swamping the
reactance with resistance. This *seems* to have fixed the problem but I
need to be sure before this load of kit gets shipped half way round the
world. Last thing I want is a midnight phone call saying "This *&^% thing
you sent doesn't work".

Just to clarify, mine doesn't swamp the reactance with resistance, it
actually removes the reactance totally - the load is purely resistive.

If you are driving many loads, what about configuring it as a proper
distribution amp. Use a separate 50 ohm resistor to feed each cable,
and load the far end of each with 50 ohms. Everything is properly
loaded for flat response, nicely buffered from everything else, and
guaranteed stable. You get a net 6dB loss, which you can make up
simply in the feedback network.

d