Hi all,
Spent a few minutes more with the VI+. I hooked it to a dummy load and
keyed the transmitter in TUNE mode. With the knob on FWD power, the meter
did move in sync with the power being drawn from the DC supply (15-20 A
depending on mode), so the meter movement appears indeed not to be
completely dead.
However, it's sticky. On the FWD meter setting, when you raise the TX
power and then turn it back down, the needle gets stuck midway on the dial
and won't go down to zero. Firmly tapping on the front face does
eventually get it to zero out, and then you get one pass from zero to max,
whereupon it sticks again when the power is turned down.
Obviously this is not very useful. Anyone know how to unstick or
recondition this kind of movement? Maybe there is some old-time collective
wisdom I don't know about. Or am I resigned to finding a new S meter from
someone's surplus pile? [If so, who has these kinds of surplus parts now?]
Cheers/73
Phil W1PJE
On Sat, Nov 17, 2018 at 6:17 AM Phil Erickson <phil.erickson@gmail.com>
wrote:
> Hi Jim,
>
> Thanks - already checked that part out with the S meter unplugged. I
> could adjust R25 through its full range and see the voltage on a DMM go up
> and down, so the pot wasn't at a dead spot, but I could certainly see where
> this might happen in other cases.
>
> 73
> Phil W1PJE
>
> On Sat, Nov 17, 2018 at 12:51 AM <w3ka@lycos.com> wrote:
>
>> Phil OM,
>>
>> I had similar issues with my TT Omni 6+. S meter readings were there
>> but extremely low.
>>
>> On the IF/AF board, there is an S meter adjust pot, R25 a 1K trimmer
>> control. Mine was
>>
>> sitting on a "dead spot". Gently rock the pot up and down, (not too
>> much, just enough to free the dead spot on
>>
>> the trimmer).. World great on my VI+ and resolved the S meter issues.
>> Good luck
>>
>>
>> 73, Jim W3KA
>>
>>
>>
>> On 2018-11-17 04:41, Phil Erickson 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@gmail.com
>
--
----
Phil Erickson
phil.erickson@gmail.com
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