[TenTec] Omni VI+ S meter troubleshooting

MadScientist dukeshifi at comcast.net
Sat Nov 17 00:23:53 EST 2018


Well, an antenna is OK… Just identify your self after briefly throwing a carrier on the air. This test will save  you a lot of grief.

Gary



> On Nov 16, 2018, at 10:55 PM, Phil Erickson <phil.erickson at gmail.com> wrote:
> 
> Haven't tried TX mode yet because I didn't have a dummy load when I was
> doing testing.  I was hoping there was a quick way to test the meter
> without that.
> 
> 73
> Phil W1PJE
> 
> On Fri, Nov 16, 2018 at 11:41 PM Phil Erickson <phil.erickson at gmail.com <mailto:phil.erickson at gmail.com>>
> wrote:
> 
>> Hi all,
>> 
>>  I've just acquired an Omni VI+ with all the filters including the Inrad
>> roofing filters.  It is very sensitive as far as RF goes on all bands using
>> a HP 8640B signal generator as a calibrated source.  However, the S meter
>> does not work at all when AGC is enabled (or for that matter, when it
>> isn't, although of course AGC should be on to generate a reading).
>> 
>>  I pulled the covers off and examined the IF/AF board.  According to the
>> manual section 4-7, the voltage driving the S meter is at connector 58 (a 2
>> pin one).  I pulled the connector off and, using a multimeter, was able to
>> verify that a correct voltage was there on the pins in the ~200 to 800 mV
>> range.  I was able to make that voltage go up and down as expected by
>> manipulating  the RF gain, and also by changing the signal generator's
>> amplitude.  The R25 and R29 trimmers also made the voltage move up and down
>> as expected ("full scale" and "offset').
>> 
>>  So I think the S meter driving circuitry is working fine in RX mode from
>> the IF/AF board..
>> 
>>  However, the manual is not clear on how the meter is multiplexed with
>> the TX section, which I haven't tried yet as I'd like to get the receiver
>> going first.  I tried moving the meter selector knob to a few positions,
>> but of course all of those are for when the TX is engaged (FWD, SWR, Ic,
>> PROC) so it did not help.
>> 
>>  Does anyone have suggestions?
>> 
>> 1)  Maybe the meter movement has failed?  If so, does anyone have any
>> tips to isolate the meter and drive it with an appropriate voltage to see
>> if the needle moves?
>> 
>> 2)  Is there any other check to see if the meter is somehow not paying
>> attention on RX because it's stuck on one of the TX meter settings?
>> 
>>  3) Are there any other connectors to reseat?
>> 
>> Thanks in advance -
>> 
>> 73
>> Phil W1PJE
>> 
>> 
>> 
>> 
>> --
>> ----
>> Phil Erickson
>> phil.erickson at gmail.com
>> 
> 
> 
> -- 
> ----
> Phil Erickson
> phil.erickson at gmail.com <mailto:phil.erickson at gmail.com>
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