[TowerTalk] RadioWorks line-isolator spec.

[David Jordan]

Chuck,

Not because I'm a VA amateur but I've used several of the Radio Works 
Isolators and in every case they have resolved my RFI problems which 
were due to RF floating on the shield of the coax. Never had a SWR 
problem with any of the baluns or isolators on any freq. from 160-10m, 
running the legal limit.

I use what works and leave the numbers to those smarter then me.

73s,
dave
wa3gin

Chuck Counselman wrote:

> 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 common-mode-choking impedance of their 
> so-called 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 37-microhenry 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 L-R 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 3.5-MHz range like that of a _series_ L-R circuit, not at all like 
> a parallel L-R circuit, I told Jim Thompson that I thought his 
> advertising was misleading.  He ignored me, too.
>
> -Chuck, W1HIS
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