At 9:35 AM 0500 1/28/03, Mike Wetzel W9RE wrote:
>To add to your RadioWorks info, I had 3 of their baluns...and found
>that the baluns exhibited a very high swr on 10 [meters].... The
>baluns seemed ok below that frequency (21 Mhz). I informed them and
>they ignored me.
About three years ago, suckered by RadioWorks' advertising which
seemed to say that the commonmodechoking impedance of their
socalled line isolator at 3.5 MHz was _extremely_ high, of the order
of 100 kohms, I bought two of these devices.
In fact the complex impedance at 3.5 MHz is about ( 0 + 800 j ) ohms.
Yes, zero ohms resistance plus eight hundred ohms reactance. The
uncertainty in this complex value is a couple of ohms in the real
part and a few percent in the imaginary part. In other words, at 3.5
MHz the device is a 37microhenry inductor with a very high Q,
greater than 400.
An exchange of email with RadioWorks' proprietor Jim Thompson
eventually revealed his justification for advertising "100 kohms."
In the parallel LR circuit having the same impedance at 3.5 MHz, the
value of L is about 37 microhenries and the value of R is about 100
kohms.
Since the complex impedance of such a device varies with frequency in
the 3.5MHz range like that of a _series_ LR circuit, not at all
like a parallel LR circuit, I told Jim Thompson that I thought his
advertising was misleading. He ignored me, too.
Chuck, W1HIS
