Define 'Efficient' before you engage in this discussion.

"When I was a youngster, back in the olden golden days, transformer
efficiencies exceeded 98%, but that was for 60 Cycle [olden days
language] power distribution systems."

H U G E G R I N

Deacon Dave, W1MCE
+ + +

W5DXP wrote:

Art Unwin KB9MZ wrote:

Since transformers are touted as being efficient
I was wondering how it would compare with
the normal tuner.


Who touts transformers as being efficient? And efficient
compared to what?

Dave Shrader wrote:
Define 'Efficient' before you engage in this discussion.

OK, let's say as efficient as a transmission line transformer
over an entire range of frequencies. I don't think you will
find a normal transformer that is as efficient as a transmission
line transformer over the entire HF frequency range. But I could
be wrong.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil, if I go back in time a long way, to the days of transformer
design, I recall that core loss increased as an exponential of
frequency. The exponential was greater than '1.2' and less than '2.0'.

Now, magnetic materials have changed, since the invention of the wheel,
but I still suspect that losses in magnetic materials are exponential,
even in new materials.

So, in a transformer I would expect core loss to increase exponentially
from 1.8 to 29.7 MHz.

In a balun, well I don't know!

Shortly after the invention of the wheel I came into the ownership of a
B&W air wound balun rated at 250 watts continuous that I used for over
35 years. I dumped it as part of the move from Massachusetts to New
Hampshire. That was DUMB! But, using air instead of magnetic material
certainly minimized losses grin.

Back to the Modern Age. How efficient is a transmission line
transformer? [TBD %] Can you quantify a suitable number or will it
remain a qualitative statement?

Deacon Dave, W1MCE
+ + +

W5DXP wrote:
Dave Shrader wrote:

Define 'Efficient' before you engage in this discussion.


OK, let's say as efficient as a transmission line transformer
over an entire range of frequencies. I don't think you will
find a normal transformer that is as efficient as a transmission
line transformer over the entire HF frequency range. But I could
be wrong.

Dave Shrader wrote:
Back to the Modern Age. How efficient is a transmission line
transformer? [TBD %] Can you quantify a suitable number or will it
remain a qualitative statement?

Looking at some of the graphs in Jerry Sevick's book, _Transmission_
Line_Transformers_, it looks like about .05 dB maximum loss from 3
to 30 MHz. Note that figure is for perfectly matched resistive loads.

A transmission line transformer carries a high flux density for common
mode but not for differential mode. An ordinary transformer carries
a high flux density for differential mode. That's got to make a
difference.
--
73, Cecil http://www.qsl.net/w5dxp



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For design, frequency-response, insertion-loss of 4:1 impedance ratio,
transmission line HF transformers (voltage Baluns), download program BALUN4
from website below -
---
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go to http://www.g4fgq.com
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