wrote in message
oups.com...
Have you experience running 100w into one of these transformers
yourself? I kinda doubt they would take any watts.

If I understand you correctly you are talking about the little unit
that connects the cable to the old 300ohm input of 1970s type tv.
These units have very small toroids, only maybe a quarter inch in
diameter, that are designed for microvolts of excitation at the bottom
end of TV band - which is somewhere near say 50Mhz. They will not
handle any magnitizing flux and I would bet a watt at 20m would
overheat it.

regards,
Bob
N9NEO

Those VHF 75/300 ohms transformers where designed for the 48 to 300 MHz VHF
TV-segment. The neosid core is not that small: it just covers my thumbnail.
It indeed can handle 100 watts on 14 MHz. I tested it thoroughly: a friend
had taken his transceiver to Costa Rica where he was visiting family and I
wanted to raise an antenna very quickly to stay in touch with him. I
suspended a folded dipole under the roof of my house and used the described
VHF bal/un to feed it. We had (almost) daily skeds on 14 MHz. The "almost"
was not due to propagation but had more to do with the fact that the
electricity plant was only up 3 or 4 days a week in Costa Rica at that time.

Later I used the same bal/un with a folded dipole for the 20 m band made
with twin lead.

I never used it on lower frequencies. I am sure that it would get pretty hot
with 100 watts on 80 m.

Kind regards,

Phil