Thanks Tom
I guess I really should have done that in the first place. They do appear to be
the same mix as R ~ X at around 2 MHz in each case. I tested a few of each type
and the variations in impedance were quite substantial, but didn't appear to be
correlated to the DC ohmeter check.
I guess the moral of the story is not to measure a parameter that the
manufacturer doesn't specify!
73 RogerVE3ZI
From: Tom W8JI <w8ji@w8ji.com>
To: Roger Parsons <ve3zi@yahoo.com>; Topband <topband@contesting.com>
Sent: Monday, 1 June 2015, 11:31
Subject: Re: Topband: Binocular Cores
You really need to do a single loop through the core windows and measure the
impedance with some sort of analyzer. Even an MFJ259B with a short
connection to the jack will work well for this.
If the resistance equals the reactance down somewhere around 2 MHz, it is 73
material.
If R=X someplace much higher, you can be sure it is a different mix. The Q=1
frequency, where R=X or where loss tangent crosses reactance, tells you the
material better than anything else you can do.
That is how I quickly sort unknown cores.
73 Tom
----- Original Message -----
From: "Roger Parsons via Topband" <topband@contesting.com>
To: "Topband" <topband@contesting.com>
Sent: Monday, June 01, 2015 10:13 AM
Subject: Topband: Binocular Cores
>I have some binocular cores which I know are FairRite mix 73. I have others
>which I thought were also mix 73. However, the first ones measure about 50k
>Ohms with ohmeter prods onto their surface, whereas the others only measure
>about 1k Ohm. I don't believe that that is a defined parameter, and am
>aware that the test is not very scientific, but I am surprised to see such
>a difference. Thoughts?
> 73 RogerVE3ZI
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2014.0.4800 / Virus Database: 4311/9916 - Release Date: 06/01/15
>
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
|