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Re: OMB GP-6
To: CRTech <crtech@crtech.org>
Subject: Re: OMB GP-6
From: JIm Turvaville <jimturbo61@yahoo.com>
Date: Thu, 2 Nov 2017 17:35:17 +0000 (UTC)
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In-reply-to: <CAHL64sHAKrOMR1EpJjgHcKcQmos7wL3aLJa6UGCyGn3WJApM7A@mail.gmail.com>
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Reply-to: JIm Turvaville <jimturbo61@yahoo.com>
I've worked on those antennas a lot more than I wanted to, and it's not been pretty most of the time.  The stainless steel set screws gall up really bad and you end up drilling them out and re-tapping to adjust the arms.  The Gamma is very critical to tune and even the shape of it will change your VSWR wildly.  Tuned one and the tower guy bent the Gamma taking it up the tower and it would not load at all. Like their Italian cousins from Bext and RVR, they are much more fragile than the real world can manage in most of my installs.  I have had one specific bay just flatly refuse to tune better than 1.5 VSWR no matter what I adjusted.  I can only wish you luck Kevin - you may need it. 
Jim "Turbo" Turvaville 
SBE Certified Radio Engineer 
Turbo Technical Services 
 PH: 719-459-1859 

From: Kevin Kidd <kkbroadcastengineering@gmail.com>
To: CRTech <crtech@crtech.org>
Sent: Thursday, November 2, 2017 12:07 PM
Subject: [CRTech] OMB GP-6

Hi all,

Does anybody have a manual for the above antenna?  Specific tuning info?  Any experience with it?  Any advice other than cutting it up for scrap?

I have one with high (abt 1.6:1) but not astronomically high VSWR and the new station owner is contemplating replacing an old Collins TX with a new Nautel.  Most any SS TX is not going to be happy with 1.6vswr but a new antenna isn't in the budget right this second.


Kevin C. Kidd, CSRE/AMD
Lawrenceburg, TN
AM Ground Systems Company  -  WD4RAT
kkidd@kkbc.com  --  866-22-RADIO -- 866-227-2346

References: OMB GP-6
(Kevin Kidd <kkbroadcastengineering@gmail.com>, 2 Nov 2017 17:07:35 -0000)
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