[TowerTalk] TowerTalk Digest, Vol 75, Issue 18

[John Lyles]

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 at losalamos.com>
> Subject: [TowerTalk] impedance measuring antennas
> To: towertalk at contesting.com
> Message-ID: <f671e112b9d295390dc279010cffe602 at 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 at thepoint.net
> Subject: Re: [TowerTalk] impedance measuring antennas
> To: jtml at vla.com, John Lyles <jtml at losalamos.com>
> Cc: towertalk at contesting.com
> Message-ID: <20090306143357.ex9qasgk4k440owo at 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
> 
>