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Re: [TenTec] Omni VI Mystery

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Omni VI Mystery
From: John King via TenTec <tentec@contesting.com>
Reply-to: John King <k5pgw@yahoo.com>, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Wed, 30 Jul 2014 02:25:10 -0700
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
Jim I have other model Ten Tec rigs to operate CW, but I haven't noticed the 
problem described with my Omni  VI. Do you know if this is a problem exhibited 
by ALL  Omni VIs, SOME Omni  VIs or a FEW? I love my Omni VI and have no plans 
of replacing it.
Thanks for telling us about the situation with your Omni VI. 73, John, K5PGW


--------------------------------------------
On Tue, 7/29/14, Jim Allen <jim.allen@longhornband.net> wrote:

 Subject: [TenTec] Omni VI Mystery
 To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
 Date: Tuesday, July 29, 2014, 5:43 PM
 
 Some will remember the thread a few
 months back in which I described the
 problem I had been having making contacts with the Omni VI
 opt 3 I have.  I
 realized there was a problem with the radio when I used my
 706MKIIG at 5
 watts one day in a QSO party with the same antenna and made
 contacts all
 over the place no problem.
 
 It turns out the radio is off somehow by about the amount of
 the sidetone,
 so when I zero beat a CW station (match tone set in
 sidetone) and transmit,
 the other station hears no tone.  My signal is below
 his audible range
 and/or outside his passband.
 
 We did some testing here between the 706, the Omni and other
 stations and
 determined that the problem could be gotten around by
 setting the XIT on to
 -whatever the sidetone was, in my case, usually 700Hz. 
 That made the radio
 work, except for the transmit frequency being off, and
 hopping around with
 QSK, but it put my signal at the frequency that other
 stations would hear
 it.
 
 I was not content to leave it like that so sent it to TenTec
 to check the
 alignment and/or correct whatever was occurring to cause
 this.  To my
 chagrin, Paul reported that the radio was just fine, working
 as designed,
 no problems, aligned just fine working per factory spec,
 nothing needed,
 etc., and sent it back.  At least he didn't charge me
 for this.
 
 About that time, I found a Omni VI+, with full filters and
 speaker/power
 supply at a price that I found attractive, so I bought
 it.  I've been using
 it for more than a month, works great, just the way you
 expect, and have no
 trouble making contracts, in the context of a 100 watt radio
 with a so-so
 antenna anyway.  I used it for Field Day at 5 watts
 output to a homebrew
 S9v31 vertical and was very pleased with the performance,
 given the
 circumstances.
 
 This Omni VI still bugs me though, so I set up all three
 radios and did
 some testing.  I set all three radios on 14.030, using
 the no output on the
 two Omnis and a dummy load on the 706.  When I transmit
 using the 706, I
 hear that signal on 14.030 in the Omni VI+, and at 14.030.4
 zerobeat on the
 Omni VI, in both cases matching the tone using that function
 on the CW
 button.  Both sidetones are set at 700Hz.
 
 When I set the Omni VI to 14.030 and transmit, I zero that
 on the Omni VI+
 at 14.030.04, a 40 Hz difference.  On the 706, I zero
 the signal at
 14.030.07.  There is a slight difference in the
 calibration of these 3
 radios, and they sometimes vary 10 Hz or so anyway.
 
 When I hear the Omni VI+ and zerobeat that signal in the
 Omni VI, it is at
 14.030.42. In a QSO, I would hear the Omni VI+ calling and
 zero that
 signal.  When I called using the Omni VI, on the zero
 frequency, I hear it
 in the VI+ as a very low pitch, almost a buzz.  When I
 turn on XIT, at
 -700Hz and call, the Omni VI+ hears it with a higher audio
 tone, and zeros
 the Omni VI signal at 14.029.79.
 
 It looks to me like perhaps the Omni VI is off calibration
 slightly, but
 that doesn't explain why it doesn't transmit with the proper
 offset as
 expected, without XIT being on anyway.
 
 I tried a QSO with these three radios.  I call CQ using
 the 706, I "hear"
 and zero that signal on the Omni + at 14.030, the same as
 the 706.  I reply
 using the Omni VI+ and hear the reply in the 706, with a
 ~700 hz. tone.  I
 hear and zero the same signal from the 706 using the Omni
 VI, at
 14.030.39.  When I reply to the 706, the 706 hears a
 strong signal at a
 very low audio tone, inaudible.  When I click XIT -7 on
 the Omni VI, I hear
 it in the 706 just fine.
 
 I have consulted off list with a very clever and exceedingly
 knowledgeable
 Tentec user, who probably wishes to remain anonymous, and he
 has suggested
 I check the alignment myself.  This fellow also
 suggested a way to
 determine if one or more of the parts in the affected
 circuit have gone
 bad.  I do not have a frequency counter, and do not
 know where to obtain
 access to one.  What kind of frequency counter ought to
 be used for this?
 
 Is there anyone who works on these radios, other than
 Tentec, who has the
 test gear etc to resolve this?
 
 There has to be an explanation why the VI doesn't work like
 the VI+ in this
 respect.
 
 TIA
 
 73 de W6OGC  Jim Allen
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