Certain VFO B freqs produce noise on certain VFO A freqs IC-R30

[flanker86]

Again - is it my unit or all of IC-R30 have it. When 131.800 AM is entered in VFO B, 119.150 AM has noise on VFO A. Another pair is 131.600 AM on VFO B and noise on 356.450 AM on VFO A. This is with or without an antenna. Please help me as it is fairly easy to check.

Sample movie:
VID_20181229_103900.mp4

 

[Hit_Factor]

The two VFOs are different, so they will behave differently.

My R30 has the same noise you describe, a birdie. https://www.eham.net/ehamforum/smf/index.php?topic=14887.0;wap2


Does this help? From the manual. Time to break out the calculator and look for harmonics...

5

and

https://forums.radioreference.com/t...ive-than-vfo-b-or-my-ic-r30-is-broken.380580/

 

[flanker86]

Ok, so IF for B is 46.350 MHz, my tuned is 131.800, so to LO is 85.450 MHz or 178.150 MHz. According to my calculations non of these should produce a birdie on 119.150 AM. If I am wrong, please correct me.

 

[Hit_Factor]

Not sure if this calculator would help you. I'm learning as we go along.

Mixer Spur Calculator

 

[flanker86]

OK, few questions. Why did you input LO 70-81? 118-46.35 is 71.65 and 137-46.35 is 90.65, so the range should't be 71 to 91? And why IF bandwidth is 20.4 - is it from spec?

 

[CQ]

Have it as well with those pairs. It's audible with antenna but have to crank up the volume with no antenna. Don't have any of those frequencies in my memories so never ran into it.

Annoy=Avoid

 

[Hit_Factor]

20.4 Mhz represents broadcast FM bandwidth. I couldn't find a spec on it, it's possible bandwidth is set by the selected mode, try 6 or 8 for AM.

LO tuning range was selected because that's what gives the final RF values in the air band. Tinker with the values in the calculator and you'll see why those values were used.

What does ICom have to say?

I'm with CQ on this one annoy = avoid.

 

[Hit_Factor]

I just realized a big error on my part, 20.4 Mhz of bandwidth is wrong, 20.4 Khz is better.

 

[Hit_Factor]

This looks better for AM

 

[RFI-EMI-GUY]

View attachment 67281
This looks better for AM

Could you share a source for the spur program? I could use it, been using a very clunky method in past.

 

[Hit_Factor]

The link is above the graphic in post #4.

Have you any comments on the birdie we're chasing down?

73, K8HIT
Icom: IC-7300 IC-PW1 ID-5100A ID-51A Plus 2 IC-R30 Hytera PD782G Uniden SDS100 DVMega SDRplay RSPduo

 

[RFI-EMI-GUY]

I was looking to see if the radio has an "IF Shift" to manually move the local oscillator. The manual says nothing. Spurs like this in a tiny radio are inevitable. I have not worked out the math, but not surprised.

 

[Hit_Factor]

I looked for an IF shift as well, negative results as well.

73, K8HIT
Icom: IC-7300 IC-PW1 ID-5100A ID-51A Plus 2 IC-R30 Hytera PD782G Uniden SDS100 DVMega SDRplay RSPduo