[Elecraft] 160m noise

Wed Nov 13 17:57:49 EST 2019

Hi,

I think I found the problem. Since I had another K3 I took the KR mixer board from one of the radios and put in the one with the problem and the noise went away. So I started measuring on the board and as soon as I put the oscilloscope probe on the +5V pin the noise went away. So by the looks of the schematic +5V is fed into a voltage divider which is also connected to the LO and switches the multiplexer doing the mixing. So I measured the voltage at the input to the "mixer" and the peak level was right at +2V which is also the Vih of the circuit. So I guess it ended up barely switching any thus just generating noise instead. By adjusting it so it switches properly the problem went away.

73 de Mike, SM2WMV (SJ2W)
http://www.sj2w.se/contest/

On 8 November 2019 at 23:26:32 +01:00, Mikael Larsmark <mike at sm3wmv.com> wrote:

> Hi again,
> 
> I tried the factory settings and the problem does remain. I made a Youtube clip which shows it and the noise goes away below 1320kHz and above 2150kHz.
> 
> 
> Here is the clip,<<https://youtu.be/Ju5oMhq2YEE>>
> 
> 
> So I really feel this is a problem in the radio and not anything else.
> 73 de Mike, SM2WMV (SJ2W)
> <http://www.sj2w.se/contest/>
> 
> 
> On 8 November 2019 at 22:53:25 +01:00, RIchard Williams <<richarddw1945 at yahoo.com>> wrote:
> 
> 
> > Well, that was a good idea (only works if you have a second radio). I would try Eric's suggestion to reload a good EEINIT file. Can't beat Elecraft for support.
> > 
> > 
> > Dick, K8ZTT
> > 
> > 
> > 
> > Sent from Yahoo Mail on Android <<https://go.onelink.me/107872968?pid=InProduct&c=Global_Internal_YGrowth_AndroidEmailSig__AndroidUsers&af_wl=ym&af_sub1=Internal&af_sub2=Global_YGrowth&af_sub3=EmailSignature>>
> > 
> > 
> > 
> > > On Fri, Nov 8, 2019 at 11:28, Mikael Larsmark
> > > <<mike at sm3wmv.com>> wrote:
> > > 
> > > Hi Dick,
> > > 
> > > I have tried plugging everything out of the radio except the power supply. Then I took another K3 and made sure I did not have the same problem on that radio which I did not have, it was totally quiet when unplugging the antennas. I took the power supply cable from that K3 and plugged into the one with problem (still no other cables connected) and still the same noise. I also tried a dummy load on the TX ant port but no success.
> > > 
> > > 
> > > So I doubt it is anything generated locally since the setup is identical with the other K3 when switching them out. Plus it is dead quiet on all other bands when unplugging the antennas.
> > > 73 de Mike, SM2WMV (SJ2W)
> > > <<http://www.sj2w.se/contest/>>
> > > 
> > > 
> > > On 8 November 2019 at 21:55:26 +01:00, RIchard Williams <<<richarddw1945 at yahoo.com>>> wrote:
> > > 
> > > 
> > > > First, I would try using just a battery to make sure it is not power supply. Then try turning off everything but your radio in the shack. If the noise is still there, throw the master breaker to the house to see if it might be something in your house.
> > > > 
> > > > 
> > > > Or you might take your radio and a battery somewhere that is not near any noise sources and see what your S meter shows. If you still have the noise, maybe someone else has some thoughts.
> > > > 
> > > > 
> > > > Dick, K8ZTT
> > > > 
> > > > Sent from Yahoo Mail on Android <<https://go.onelink.me/107872968>?pid=InProduct&c=Global_Internal_YGrowth_AndroidEmailSig__AndroidUsers⁡_wl=ym⁡_sub1=Internal⁡_sub2=Global_YGrowth⁡_sub3=EmailSignature <<https://go.onelink.me/107872968?pid=InProduct&c=Global_Internal_YGrowth_AndroidEmailSig__AndroidUsers&af_wl=ym&af_sub1=Internal&af_sub2=Global_YGrowth&af_sub3=EmailSignature>>>
> > > > 
> > > > 
> > > > 
> > > > > On Fri, Nov 8, 2019 at 10:01, Mikael Larsmark
> > > > > <<<mike at sm3wmv.com>>> wrote:
> > > > > 
> > > > > Hi,
> > > > > 
> > > > > I am having an issue which confuses me quite a bit. When I unplug my antennas and listen to 80m for example I have very low noise and the S-meter does not light up a single bar. When I go to 160m and do the same thing I have S3-S4 and I can hear a much higher noise level. It is the same behavior regardless if I use the RX antenna or the ANT1 jack (none with any antenna). I have the same settings on both bands.
> > > > > 
> > > > > 
> > > > > I also tried to do a factory reset but behavior remains.
> > > > > Any idea what this can be?
> > > > > 
> > > > > /Mikael, SJ2W
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> > > 
> > > 
> > > > > 
> > > > > 
> > > > 
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