----- Original Message -----
From: "Jim Brown" <jim@audiosystemsgroup.com>
To: <topband@contesting.com>
Sent: Friday, July 13, 2012 9:35 PM
Subject: Re: Topband: Mother of all ferrite common-mode coaxial chokes
> On 7/13/2012 6:21 PM, ZR wrote:
>> ----- Original Message -----
>> From: "Jim Brown" <jim@audiosystemsgroup.com>
>> Cc: <topband@contesting.com>
>> Sent: Friday, July 13, 2012 4:37 PM
>> Subject: Re: Topband: Mother of all ferrite common-mode coaxial chokes
>>
>>
>>> On 7/13/2012 12:09 PM, ZR wrote:
>>
>> Thats correct at UHF and up but what is the error you have actually
>> measured
>> at 1.8 MHz?
>
> The errors involved are NOT limited to UHF -- I've observed serious
> errors in the lower HF spectrum (i.e., below 10 MHz). It's why Chuck
> thinks the resonance of his chokes are as low as they are -- in reality,
> they resonate at a much higher frequency. And the errors are even
> greater with higher Q materials like #61.
** Define serious errors and using what for measuring?
>
>>> Quoting from Wes Hayward on the subject of measuring high impedances:
>>>
>>
>>
>> >From a quick glance thru that paper I dont see much benefit of RF I-V
>> >below
>> about 100MHz. What am I missing here?
>
> These are not simple issues. It takes far more than a quick glance --
> you need to STUDY this stuff. I've provided some excellent references
> that are worthy of the effort. The issue is NOT the FREQUENCY of the
> measurement that causes the error, it is the fact that the magnitude of
> the impedance differs so much from 50 ohms. Wes is measuring at VHF, but
> I'm mostly measuring from 160M up to 10M.
** Ive read all that Agilent and other stuff when published since it was
part of the engineering library at work. Since we were involved with 10
to100+ GHz it was more a curiosity than applicable.
I just dont see the benefit of so much bother since the 4815A seems to do
whats needed and rocket science accuracy isnt required....just add a few
more beads if it makes you happy.
Carl
KM1H
> 73, Jim K9YC
>
>
>
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