SDS100 Interference with SDS200

[Romeomike2709]

Thank you in advance for any help.

I’ve noticed when I place my SDS100 near my 200 the reception is choppy. This is a bit shocking to me as I normally have my equipment in close proximity. My second SDS200 has no issues being close to the other 200. Anyone have any suggestions about why this may be happening.

 

[doctordialtone]

I’ve noticed when I place my SDS100 near my 200 the reception is choppy.

That's interference due to "Beat Frequency Oscillation".

It occurs when the IF section of the two radios interfere with each other.

Intermediate frequency - Wikipedia

en.wikipedia.org

Examples

• 110 kHz was used in Long wave broadcast receivers.[1]:159
• Analog television receivers using system M: 41.25 MHz (audio) and 45.75 MHz (video). Note, the channel is flipped over in the conversion process in anintercarrier system, so the audio IF frequency is lower than the video IF frequency. Also, there is no audio local oscillator, the injected video carrier serves that purpose.
• Analogue television receivers using system B and similar systems: 33.4 MHz. for aural and 38.9 MHz. for visual signal. (The discussion about the frequency conversion is the same as in system M).
• FM radio receivers: 262 kHz, 455 kHz, 1.6 MHz, 5.5 MHz, 10.7 MHz, 10.8 MHz, 11.2 MHz, 11.7 MHz, 11.8 MHz, 21.4 MHz, 75 MHz and 98 MHz. In double-conversion superheterodyne receivers, a first intermediate frequency of 10.7 MHz is often used, followed by a second intermediate frequency of 470 kHz. There are triple conversion designs used in police scanner receivers, high-end communications receivers, and many point-to-point microwave systems. Modern DSP chip consumer radios often use a 'low-IF' of 128kHz for FM.
• AM radio receivers: 450 kHz, 455 kHz, 460 kHz, 465 kHz, 467 kHz, 470 kHz, 475 kHz, 480 kHz.[10]
• Satellite uplink-downlink equipment: 70 MHz, 950–1450 MHz (L-band) downlink first IF.
• Terrestrial microwave equipment: 250 MHz, 70 MHz or 75 MHz.
• Radar: 30 MHz.
• RF Test Equipment: 310.7 MHz, 160 MHz, 21.4 MHz.

 

[Romeomike2709]

So a solution is to keep them apart?

 

[doctordialtone]

So a solution is to keep them apart?

Exactly!

 

[Romeomike2709]

Thanks Doc

 

[teknishun]

Thank you in advance for any help.

I’ve noticed when I place my SDS100 near my 200 the reception is choppy. This is a bit shocking to me as I normally have my equipment in close proximity. My second SDS200 has no issues being close to the other 200. Anyone have any suggestions about why this may be happening.

Please elaborate - define "near". Which radio becomes choppy? I do this all the time with my SDS200 and SDS100 being about
9 inches (I just checked!) from each other. The SDS200 is running off an outdoor antenna and the SDS100 has a rubber duck
made for 700 / 800 MHz. I am aware of no problems. Both scanners are scanning the same system but each scanner has a
different site to scan.

WOULD - Adjusting the filter settings on one or both scanners help fix this problem?

WOULD - The 7/IFX key for Intermediate Frequency Exchange be of any use here? IFX is very briefly explained in the
SDS200 manual under "Main Features" and is on or near page 7 of the manual, depending on which issue you have.

 

[doctordialtone]

WOULD - The 7/IFX key for Intermediate Frequency Exchange be of any use here?

Good point. Yes, the IFX option MAY help.

That's one of the things it's designed for. YMMV.

 

[Romeomike2709]

They were about 12 inches apart. The 100 seems to be working fine over the last 6 hours. I’ve placed them about 24 inches apart and since the 100 is fine I’m happy.