On Jan 21, 9:56*am, Michael Black wrote:
On Fri, 20 Jan 2012, coffelt2 wrote:

"it9xxs" wrote in message
...

Hi, I'm looking for a low-power modulation transformer. I'd like to
build a QRP (5W?) tube AM transmitter for the 10m band. Thanks, 73s,
IT9XXS

Are there any old tube type CB radios around?

I suppose size might matter, but sometimes old tube type
power transformers can come up with a "close enough"
impedance ratio.

I barely see solid state CB *sets around, so I suspect the
tube ones have long disappeared.

Besides, he's not in North America, and CB was mostly a North American
thing.

Another old time solution was to find a tube type speaker
output transformer, with the secondary on an outside winding
which could be stripped away, making room to add a new
secondary. (keep a log of turns removed on the old
secondary, so a good estimate of new turns required)
(to get impedances fairly close.. precision not required)

Or find a 400Hz transformer, nobody wanted them so at one time they were
not only available but cheap. *Various articles said they worked fine,
since voice didn't have to go down to 60Hz.

* * Michael *VE2BVW

Get a single ended triode type of audio output transformer and drive
it from a hi-fi amp.