Tuner/balun efficiency
 

Which should be more efficient: Using an ATR-30 to match a 300 ohm load
directly through a W2DU type balun, or using the same tuner to match 150
ohms using a CWS Bytemark 2:1 balun? Bandwidth is not a concern.I already
have the tuner and baluns. I realize there may be little difference between
the two choices, but I will be using the tuner and one of the baluns
anyway.

73,
bob

Bob-- Effecient?? That term can apply to the LOSS in your feed line/
VSWR?Frequency!
and, obviously, the POWER HANDLEING capabilities of the tuner/feedline!
But, generally, unless
you are at VHF, with couple hundred feet of feedline (I.E. 10 meters, or
below)! any effeciency
difference will never be HEARD!! the loss diff will probably be less than 1
dB!
My advice? go for it, as long as it is in your tuners power rateing, for hi
Z mismatch!
Jim NN7K

Bob sent:
"bob" wrote in message
...
Which should be more efficient: Using an ATR-30 to match a 300 ohm load
directly through a W2DU type balun, or using the same tuner to match 150
ohms using a CWS Bytemark 2:1 balun? Bandwidth is not a concern.I already
have the tuner and baluns. I realize there may be little difference
between
the two choices, but I will be using the tuner and one of the baluns
anyway.

73,
bob

Yes, Jim-- I agree with you in that the difference will be very
small, and
is more academic than anything. I have the antenna and feedline up and
working (at a portable location), so now I'm just playing with ideas. I want
a simple antenna for a small segment of 75 that will be as efficient as is
practical. I will be operating out of my truck at a power level of no
more than
500 watts, and most of the time will be barefoot. What I'm curious about is
the tradeoff of tuner efficiency between 150 ohms and 300 ohms by using
either a 1:1 balun or 2:1 balun. My guess is that there will be less
loss at
150 ohms with the 2:1 than at 300 ohms with the 1:1 W2DU type balun.
The 300 ohm window line is matched to the antenna, so there is little or no
reflected power at resonance and only 4% reflected at 3.870 and 3.4% at
4.0.
Eznec 4.0 shows that the tuner will see 317 ohms at resonance with a 1:1
balun. The system is working now, and I'm just nitpicking minor details at
this point.
Bob-- Effecient?? That term can apply to the LOSS in your feed line/
VSWR?Frequency!
and, obviously, the POWER HANDLEING capabilities of the tuner/feedline!
But, generally, unless
you are at VHF, with couple hundred feet of feedline (I.E. 10 meters, or
below)! any effeciency
difference will never be HEARD!! the loss diff will probably be less than 1
dB!
My advice? go for it, as long as it is in your tuners power rateing, for hi
Z mismatch!
Jim NN7K

Bob sent:
"bob" wrote in message
...

Which should be more efficient: Using an ATR-30 to match a 300 ohm load
directly through a W2DU type balun, or using the same tuner to match 150
ohms using a CWS Bytemark 2:1 balun? Bandwidth is not a concern.I already
have the tuner and baluns. I realize there may be little difference

between

the two choices, but I will be using the tuner and one of the baluns
anyway.

73,
bob

I neglected to mention that this is an antenna for operating portable. It
is an inverted V, 50' in the center, and 20' on the ends. 300 ohm window
line (from the Wireman) is delta matched, and is for 75 only. Settings on
the tuner (ATR-30) when at antenna resonance are the same as when using a
330 ohm carbon resistor and 359b as a source. Predictions from Eznec 4.0
appear to be very accurate (500 segments).

73,
bob


Yes, Jim-- I agree with you in that the difference will be very
small, and
is more academic than anything. I have the antenna and feedline up and
working (at a portable location), so now I'm just playing with ideas. I
want a simple antenna for a small segment of 75 that will be as efficient
as is practical. I will be operating out of my truck at a power level of
no more than
500 watts, and most of the time will be barefoot. What I'm curious about
is the tradeoff of tuner efficiency between 150 ohms and 300 ohms by using
either a 1:1 balun or 2:1 balun. My guess is that there will be less
loss at
150 ohms with the 2:1 than at 300 ohms with the 1:1 W2DU type balun.
The 300 ohm window line is matched to the antenna, so there is little or
no reflected power at resonance and only 4% reflected at 3.870 and 3.4% at
4.0.
Eznec 4.0 shows that the tuner will see 317 ohms at resonance with a 1:1
balun. The system is working now, and I'm just nitpicking minor details at
this point.
Bob-- Effecient?? That term can apply to the LOSS in your feed line/
VSWR?Frequency!
and, obviously, the POWER HANDLEING capabilities of the tuner/feedline!
But, generally, unless
you are at VHF, with couple hundred feet of feedline (I.E. 10 meters, or
below)! any effeciency
difference will never be HEARD!! the loss diff will probably be less than
1 dB!
My advice? go for it, as long as it is in your tuners power rateing, for
hi Z mismatch!
Jim NN7K

Bob sent:
"bob" wrote in message
...

Which should be more efficient: Using an ATR-30 to match a 300 ohm load
directly through a W2DU type balun, or using the same tuner to match 150
ohms using a CWS Bytemark 2:1 balun? Bandwidth is not a concern.I already
have the tuner and baluns. I realize there may be little difference

between

the two choices, but I will be using the tuner and one of the baluns
anyway.

73,
bob