[TenTec] Omni-D Frequency Displays First Two Digits are Off

[Carlos]

Hi Lyman,

Happy to hear that.
As others mentioned, you might have some noise getting into the DC bus
that is not being properly filtered and finds its way to the audio
amplification chain. If you have an oscilloscope, it should not be
difficult to trace.

Regards,
Carlos VK1EA



On 1/10/19, forum4ll at verizon.net <forum4ll at verizon.net> wrote:
>
> Please ignore my post above. I was able fix this problem by putting back the
> 560pf cap thats on pin 16 of MK50398N, display decoder chip.
>
> Lyman KK6LPW
>
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> On Monday, January 7, 2019 forum4ll <forum4ll at verizon.net> wrote:
> Hello,
> I ran into a problem with this Omni-D after solving the whining problem on
> the frequency counter. The frequency display is incorrect for 10, 14, 21,
> 28, and 29 mhz. Any 10mhz frequency will read 18mhz higher or 28 mhz. For
> 14, 21, 28, and 29 mhz, they will read 8mhz lower or  06, 13, 20, and 21mhz.
> Earlier, I made a mistake plugging in the Preset-Amp (80465) to the Display
> board (80440) where I was off by one pin. After correcting this, I noticed
> 10mhz frequencies were reading 18mhz higher. So I tore into this area again
> and tested the components on the Preset-Amp, based on my reading of the
> manual is where the first two digits are assigned, and the transistors,
> diodes and resistors tested fine although I did not test the ceramic caps.
> Putting it all back together, I now have this situation where 10mhz still
> reads 28 and bands above that are reading 8mhz lower. Still I know something
> is damaged just by the behavior when powering up. When power is turned on
> and the frequency band is switched to 14, 21, 28, or 29mhz, the display will
> appear correct for 5 to 30 seconds, then it reverts back to its minus 8 mhz
> reading. Anyone have any clue what could be wrong? I'm thinking of spraying
> some freon or a coolant on some of the components in the Display counter to
> see if I can find the bad part. Any suggestions is welcomed.
>
> Note, the lower bands i.e. 1.5, 3, and 7mhz are fine. The Preset-Amp does
> not affect the display of these frequencies.
>
> LymanKK6LPW
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