On Tue, 6 Oct 2009, Richard Knoppow wrote:

"frank" wrote in message
...
Hello Ed!

Ed Engelken wrote:

The usual fix is to use a 10-watt, 70-volt line to voice
coil
transformer. The 10-watt tap on a 70-volt line to voice
coil
transformer will provide a decent match to a 500/600 ohm
output. In a
pinch, an ordinary filament transformer will do. Get a
transformer
with a 120-volt primary and 12.6-volt secondary and
connect the 120-
volt winding to the receiver and the 12.6-volt winding to
the speaker
and you are done! --Ed

thank you for the suggestion, I do have a spare 120V
primary transformer
lying around (I live in a 240V country, so no use for it).
I could also
wire my own transformer, but that would take some time.
I don't know what a line to voice coil transformer is, can
you explain
better this part? Thanks a lot.
Best regards

Frank IZ8DWF

I've used filament transformers many times and they
work well. While the fidelity may not be as good as a
special purpose audio transformer I doubt you will be able
to tell the difference in this application.

Of course, one solution in the old days was to use a 400Hz transformer,
which were cheap and available as surplus, and which didn't have much
use in the average ham shack at the time. The idea being that since
it's intended for 400Hz, the upper frequencies might get through
the transformer better, and the loss of lower frequenices didn't matter
since for voice you didn't care about much below 300Hz.

Nowadays it may no longer be a solution, given WWII is so far in the past
and the stores that might have them for next to nothing nearby are gone
too.

Michael VE2BVW