Telamon wrote in message
I donıt understand this kind of thinking that you should not derive the
maximum benefit of an antenna that one has gone through the trouble to
put up. Your logic of all the transformer is good for is pumping up the
S meter falls flat when you donıt have enough signal for full quieting
or whether you can make out the program material at all if the signal is
very weak. I donıt see the need to call anyoneıs radio lame either.
If you are using a 70 ft random wire on HF, and you don't have enough
signal level to have a usable s/n ratio on any HF freq, you would have
a lame radio. Thats just the simple facts. Nothing personal... This is
2003. Radios are not half dead on the upper bands like to used to be
50 years ago, unless they are toys or out of alignment. There is no
"full quieting" unless you are on FM. That would generally be 10m up.
I'll repeat it again. If you hook up your antenna, and the background
noise level increases, even if just a little, you have all the s/n
ratio you need. Increasing the signal level beyond that point will not
increase the s/n ratio. It only pumps up the S meter. To see an
improvement in copy , you would need to use a directive antenna. Any
noise along with the desired signal has also increased in proportion,
so your actual s/n ratio is the same.
Sure, the signal may sound "louder" with the higher S meter reading,
but thats mainly because the level is higher, and due to the
limitations of the filter, the signal seems "wider". But the
selectivity has slightly decreased.
Most antennas output impedance is nowhere near the typical 50-ohm coax
and a transformation can remedy that.
But it doesn't matter. You don't have enough loss with the mismatch to
worry about with any decent radio. It's just not enough to knock you
out of the water. I did the math on this a few months ago, and posted
here to demonstrate this. This has been debated before many times. I
used coax feed with wild feedpoint impedances just to ensure a worst
case as far as feeder loss. It doesn't amount to enough to hurt you.
If it does, you have a lame radio. If you used a random wire direct
with no feeder, there is even less loss. For receiving, the mismatch
in that case doesn't matter enough to worry about at all.
In addition there are advantages
to preventing the coax interacting with the antenna some of which you
stated above.
Some antenna designs are better at rejecting local noise than others.
They only work if coupled properly to the coax resulting in better
signal to noise.
Sure, but that has nothing to do with the impedance tranformation. I
have no problems if people want to use transformers, I'm just saying
it's an option and should not really be needed as far as s/n ratio is
concerned. I don't use a tuner or matching on my wire antenna no
matter what freq I go to. I don't need to. I don't even come close to
needing it. I have plenty of signal level on any freq. Any doubt's and
you can pick a freq, and I'll record it and post as an mpeg.
I can dial up 28 mhz at 3 AM, and have plenty of background noise. If
I switch to the dummy load, all goes dead. Actually, I bet I could do
it at 150 mhz also...Sure, I can add my MFJ-989c tuner, and get a
perfect match as far as my radio is concerned, and maybe even pump up
the noise level an s unit or two. But it doesn't increase my s/n ratio
one whit.
BTW, any radio can be a "lame" radio, if it's not working right. I've
had a few of mine cramp up through the years. MK
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