Replace C27, a 1000 uF 16 volt electrolytic that decouples the counter unit 12
volt line from the rest of the radio’s 12 volt lines.
The only part of this radio that has anything digital that can cause a steady
whine like you describe is the counter, especially since you hear the whine
with RF gain fully down.
Likely there is switching note from the counter on the 12 volt line.
Gary
> On Jan 10, 2016, at 4:03 PM, Al Gulseth <wb5jnc@centurytel.net> wrote:
>
> This is just off the top of my head (can't find anything in a quick web
> search), but I seem to remember something about aging/deteriorating bypass
> caps (especially electrolytics) in the display subsystem being a source of
> noise on the digital Tritons and early Omnis.
>
> 73 es GL, Al
>
> On Sat January 9 2016 10:36:21 pm Kirk Smith via TenTec wrote:
>> Hello to all...My 544 Triton seems to have a high pitch whine, at low
>> volume, with the RF Gain up or down. I've read a review on E-Ham about a
>> mod that eliminated the noise.....they removed the c5 cap 750pf on the
>> logic board . Well, my schematic does not show this cap & that there's no
>> actual cap between pin 17 of the IC to Vcc. I also don't see that cap on my
>> board. Anyway, I listen at low volume & needless to say, the whine is
>> beginning to make me whine!! Any ideas before the radio heads back to TT?
>> One last thing, I tested another 544 next to it, & was quiet....my ser # is
>> 544-1618, the quiet rig is 544-1355.Thanks, Kirk
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