The OIB-2 is kind of rare. It is the HF version of the Delta OIB-1 and -3,
which are the industry standard for MW broadcast tower tuning (until last year
when Kintronics started selling the industrial version of the AIM). It works in
the presence of RF power, such as adjacent transmitting towers. Delta made them
for HF broadcasters and for DOD back in the day. QST printed an article on
building a copy of one, search for the Operating Impedance Bridge.
They have hand engraved X and R knobs, so the accuracy was very good. No
microprocessor, and better yet, no power source, passive only. One can be
carried to the top of a tower, not like an 8751 or 8753 VNA.
73
John
K5PRO
Santa Fe county, New Mexico
> Message: 1
> Date: Fri, 6 Mar 2009 12:28:19 -0700
> From: "John Lyles" <jtml@losalamos.com>
> Subject: [TowerTalk] impedance measuring antennas
> To: towertalk@contesting.com
> Message-ID: <f671e112b9d295390dc279010cffe602@losalamos.com>
> Content-Type: text/plain; charset="us-ascii"
>
> I still haven't invested in one of those portable units. i love my Delta
> Electronics OIB-2, that can measure the Z while 1 kW is transmitted to the
> antenna. Also, an Hp8751A network analyzer that I got on EBAY few years ago.
> With these two, there is little doubt in the reading. Lab grade, sure.
> John
> K5PRO
>
>
>
> ------------------------------
>
> Message: 2
> Date: Fri, 06 Mar 2009 14:33:57 -0500
> From: n8de@thepoint.net
> Subject: Re: [TowerTalk] impedance measuring antennas
> To: jtml@vla.com, John Lyles <jtml@losalamos.com>
> Cc: towertalk@contesting.com
> Message-ID: <20090306143357.ex9qasgk4k440owo@webmail.win.net>
> Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes";
> format="flowed"
>
> Isn't it a bit difficult to haul all that up to the top of a tower to
> make measurements?
> Measuring at the shack end of coax is NOT measuring the antenna.
> Don
> N8DE
>
>
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