> In the old days, when RFI did not exist (few of us are old enough not
> to remember TVI in the 50s), the Windom MIGHT have been a good idea.
> Today, with RF noise sources everywhere and home stereo rigs full of
> Pin One Problems ready to bring RF into equipment and detect it,
> Windom antennas are a really bad idea.
Unbalanced antennas or uncorrected common mode RF were never a good
idea. Even before RF noise sources on receive and other RF sensitive
electronics, one could easily encounter issues with lip burns from a
"hot" microphone. That is just one more symptom of common mode issues.
The only advantage we had in the "old days" was that the equipment
operated at much higher input levels and were thus less sensitive to
the RF voltage but the problems were still there as witnessed by the
RF burns from touching a hot chassis or hot mic.
73,
... Joe, W4TV
On 9/30/2012 3:02 AM, Jim Brown wrote:
> On 9/29/2012 9:12 PM, Robert G. Strickland wrote:
>> What I'm curious about is whether some such device, at the feed point of a
>> doublet,
>> in turn fed by window line is of any use [assuming an appropriate tuner at
>> the radio
>> end of the line]. You have said, accurately so, that a current choke at the
>> feed
>> point of a dipole [let's leave off-center fed antennas out of it at this
>> point], in
>> turn fed by coax,
>
> In all of this discussion, I have not used the word "coax." You have
> read that somewhere else.
>
>> keeps RF from flowing on the outside of the coax and subsequently
>> becoming "part of the antenna" and in turn picking up noise/etc. Another way
>> of
>> phrasing my question is, does the coax situation apply to open feeders, also?
>
> YES! That is EXACTLY what I have repeated, over and over again. It has
> NOTHING to do with coax. Coax, if it is not decoupled by a common mode
> choke, simply ADDS to the imbalance that is already present. EVERY
> transmission line needs a common mode choe at the feedpoint to decouple
> the line.
>
> Off-center fed antennas, like the so-called "Windom" in all of its
> variations, are WILDLY unbalanced. As a result, they are notorious for
> being NOISY, for putting RF in the shack, and for toasting common mode
> chokes. It is a complete fiction to feed with with parallel wire line
> and CALL it balanced, and decide that it needs a balanced tuner! The
> antenna is unbalanced, so the feedline is unbalanced, and a balanced
> tuner does nothing except transfer dollars between the purchaser and the
> seller.
>
> In the old days, when RFI did not exist (few of us are old enough not to
> remember TVI in the 50s), the Windom MIGHT have been a good idea.
> Today, with RF noise sources everywhere and home stereo rigs full of Pin
> One Problems ready to bring RF into equipment and detect it, Windom
> antennas are a really bad idea.
>
> 73, Jim Brown K9YC
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