[time-nuts] SRS FS710 spurs at 50Hz and harmonics?

Bob Camp kb8tq at n1k.org
Thu Oct 1 06:52:15 EDT 2015


It can also be a blown diode in the bridge. When that happens the ripple goes
way up. A quick check with a scope should tell you what’s happened. 50 Hz triangle
wave = blown diode. 100 Hz triangle wave = blown cap. 


> On Oct 1, 2015, at 4:04 AM, Esa Heikkinen <tn1ajb at nic.fi> wrote:
> Anders Wallin kirjoitti:
>> I seem to get very strong spurs at 50Hz and harmonics with an old
>> second-hand SRS FS710:
>> http://www.anderswallin.net/2015/09/srs-fs710-noise-measurement/
>> feature or bug? Anyone looked at the powersupply and figured out what parts
>> to change?
> If you live in a country with 50 Hz mains network then this sounds like a dead capacitor in the power supply. Usually this means that it has old fashioned linear power supply (with classic iron transformer). In that case, replace the secondary capacitors after the rectifier bridge(s). Check voltages with oscilloscope if you wanna see which ones, but it might be good idea to replace them all (there should't be many of them).
> Should be very easy to fix.
> -- 
> 73s!
> Esa
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