SDS 100 Reception Issue

[Benkasey]

I ran into a strange reception problem with my Uniden. It may not be specific to the SDS100, but I don't have another radio to test with unless I can get my Yaesu fixed. Here's the situation. I mainly use my SDS 100 in my car. I have the radio's USB charging port plugged in to a Comkia power adapter. The adapter plugs into the car's cigarette lighter socket. The Comkia has three open power ports -- 12 VDC, and two USB 2.0 ports, one putting out 2.1 amps. I plug the SDS 100 into this port, using the Uniden factory USB cable. It works fine, and keeps the SDS 100 charged up. I have to use the Comkia because my car is an older model and doesn't have any built-in USB ports. The SDS 100 is also plugged in to an external roof-mount antenna. The scanner is set to scan various public service channels in the 400 - 700 Mhz range, both analog and P25 digital. It works quite well.

Today I decided to set the scanner favorite to CHP (42 Mhz range). The scanner went around to each programmed frequency but failed to receive any signal on any of them. I tried switching antennas. Nothing. Next, I unplugged the SDS from the Comkia. Bingo. Normal reception and lots of activity on all frequencies from Marin all the way down to San Jose. I plugged the SDS back into the Comkia, but with ACC off (no power to the Comkia). Continued to receive transmissions. Turned the ACC ignition key on so power flowed to the Comkia but the engine was still off. Bamb. Stop receiving any radio transmissions.

It seems like the Comkia is acting like an RF shield or something on the lower frequencies. I would replace it with another brand if I was sure the same thing wouldn't happen with another power unit too. Any RF/electrical insights are appreciated. This seems like an obscure problem but maybe it's not.

 

[sfb88]

Did you try with the Comkia powered but the SDS not plugged into it? Maybe with the Comkia powering something else? Perhaps the Comkia is putting out some RFI in the 42 Mhz range that affects the SDS?

 

[Benkasey]

I think I may have tried that by unplugging the USB cable and not doing anything else, but I'll doubel-check tomorrow. I can also try using a long USB cable and putting the Uniden outside the car to see if the problem is proximity related, or a signal of some sort travelling through the USB cable.

 

[n1chu]

Interesting dilemma... waiting for the results of your additional tests... I

If the Komkia is emitting RF it would cause the scanner to lock up on a VHF low band frequency. That doesn’t seem to be exactly what’s happening here. And since your problem doesn’t sound coincidental, it’s a head scratcher. It could be that the Komkia is acting like an attenuator. Swapping it out should correct this if that’s what’s happening.

 

[jonwienke]

The only answer is that the comkia is generating RFI when it is powered on. Dump it and get a better USB adapter that doesn't. It the USB cable was detuning your antenna somehow, that would happen regardless of whether the comkia had power or not. If the problem only happens with power, it's 100% RFI.

 

[RRR]

USB adapters, weather cig. plug or wall outlet plug, have been nasty RFI emitters for quite some time.

Hopefully you can locate one that isn't too noisy. But that's not an uncommon issue.

 

[crippledchicken]

Comkia that's a new one on me I might recognize one if I seen it but, the name doesn't ring any bells.

 

[Benkasey]

I did more testing today. Results:

1) Attenuation (or interference) only occurs if Comkia is turned on
2) Scanner doesn't lock up. It scans everything in the favorities list. Just no reception. Like the antenna was unplugged.
3) Only occurs if USB cord is plugged in. If I unplug USB and leave Comkia turned on there is no reception problem.
4. Comkia makes a lot of computers peripherals. Places like Central Computer carry their stuff. I'll look for a replacement from another vendor. Unfortunately, I need an adapter that has both a 12 VDC round plug for my Garmin as well as 1-2 USB ports for the Uniden and other stuff.

 

[SteveSimpkin]

I did more testing today. Results:
...
4. Comkia makes a lot of computers peripherals. Places like Central Computer carry their stuff. I'll look for a replacement from another vendor. Unfortunately, I need an adapter that has both a 12 VDC round plug for my Garmin as well as 1-2 USB ports for the Uniden and other stuff.

You may also consider using a 12V accessory splitter similar to this.

https://www.amazon.com/Upgraded-Version-Electop-Cigarette-Lighter-Splitter/dp/B01HEV8LHG

 

[Benkasey]

I need something like this, that gives me both a round 12 VDC and USB ports. It's a gamble as to whether this will pose the same RF problem. Pretty much all this stuff is made in China.

https://www.amazon.com/dp/B07SF63PP7/ref=sspa_dk_detail_1?psc=1&pd_rd_i=B07SF63PP7&pd_rd_w=iYDRr&pf_rd_p=4269e1a0-a218-4fbd-9748-1cd337d2f2a5&pd_rd_wg=Hdmux&pf_rd_r=NHWB11J7K064HB71BZCG&pd_rd_r=0bae14a4-798e-41c7-83c9-93c2159fed29&smid=A3UILXPYB3XL58&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyT0tCNlI4OE5YR0M3JmVuY3J5cHRlZElkPUEwODExMjk0MUlCOUpYN0gwQTNXNSZlbmNyeXB0ZWRBZElkPUEwMjcwOTk0Q0JCSFBHUkFDU0hVJndpZGdldE5hbWU9c3BfZGV0YWlsJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

 

[sfb88]

I wonder if a solution might be to get one of those lithium battery power banks to power the SDS for a longer period and separate it from the car power. Maybe the RFI is produced by whatever components are used to drop the 12V car power down to 5V USB level?

 

[jonwienke]

The power bank has a similar voltage converter adjusting the battery output to 5V, so there's no guarantee it won't generate just as much RFI as the 12V converter.

 

[Benkasey]

There's a fair amount of discussion about the RF problem here. Some suggestions like using Anker brand, putting ferrite chokes on the power cord, etc. It's basically going to be an experiment to find out what works the way it's supposed to.

Radio static when using cigarette lighter power socket (supercub.org)

 

[crippledchicken]

I need something like this, that gives me both a round 12 VDC and USB ports. It's a gamble as to whether this will pose the same RF problem. Pretty much all this stuff is made in China.

https://www.amazon.com/dp/B07SF63PP7/ref=sspa_dk_detail_1?psc=1&pd_rd_i=B07SF63PP7&pd_rd_w=iYDRr&pf_rd_p=4269e1a0-a218-4fbd-9748-1cd337d2f2a5&pd_rd_wg=Hdmux&pf_rd_r=NHWB11J7K064HB71BZCG&pd_rd_r=0bae14a4-798e-41c7-83c9-93c2159fed29&smid=A3UILXPYB3XL58&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyT0tCNlI4OE5YR0M3JmVuY3J5cHRlZElkPUEwODExMjk0MUlCOUpYN0gwQTNXNSZlbmNyeXB0ZWRBZElkPUEwMjcwOTk0Q0JCSFBHUkFDU0hVJndpZGdldE5hbWU9c3BfZGV0YWlsJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

About anything we buy these days is made in China!

 

[crippledchicken]

Anyone ever use one of these in a car or truck? This used to belong to my Stepson before he died I've never even plugged it in and measured the voltages gonna have to try that some day. Amazon.com: Schumacher XI14 140 Watt DC to AC Power Inverter with (1) 120V AC Outlet, (1) USB Port Power Plugs into 12V Port: Automotive

 

[n1chu]

I ran into a strange reception problem with my Uniden. It may not be specific to the SDS100, but I don't have another radio to test with unless I can get my Yaesu fixed. Here's the situation. I mainly use my SDS 100 in my car. I have the radio's USB charging port plugged in to a Comkia power adapter. The adapter plugs into the car's cigarette lighter socket. The Comkia has three open power ports -- 12 VDC, and two USB 2.0 ports, one putting out 2.1 amps. I plug the SDS 100 into this port, using the Uniden factory USB cable. It works fine, and keeps the SDS 100 charged up. I have to use the Comkia because my car is an older model and doesn't have any built-in USB ports. The SDS 100 is also plugged in to an external roof-mount antenna. The scanner is set to scan various public service channels in the 400 - 700 Mhz range, both analog and P25 digital. It works quite well.

Today I decided to set the scanner favorite to CHP (42 Mhz range). The scanner went around to each programmed frequency but failed to receive any signal on any of them. I tried switching antennas. Nothing. Next, I unplugged the SDS from the Comkia. Bingo. Normal reception and lots of activity on all frequencies from Marin all the way down to San Jose. I plugged the SDS back into the Comkia, but with ACC off (no power to the Comkia). Continued to receive transmissions. Turned the ACC ignition key on so power flowed to the Comkia but the engine was still off. Bamb. Stop receiving any radio transmissions.

It seems like the Comkia is acting like an RF shield or something on the lower frequencies. I would replace it with another brand if I was sure the same thing wouldn't happen with another power unit too. Any RF/electrical insights are appreciated. This seems like an obscure problem but maybe it's not.

Two questions;
Wondering if the Comkia is deliberately providing some sort of a range extending antenna when the USB charger cord is plugged in? There are times I am parked just marginally out of cell range, where my cell phone tells me to move closer?

Would a choke help?

 

[Benkasey]

No, the Comkia is just a cigarette lighter power port. I've used it for several years. I did more research today and found many articles discussing RF interference from USB type power adapters. Interferes with ham radios. Keyless car door fobs. One guy even found that his car charger triggered the tire pressure sensor to give a false warning.

Virtually all these chargers are made in China. There are a lot of brands of these, they are probably using the same chipset or circuit board which has inadequate shielding. After more research, I found one mentioned on an airplane accessory site that has low RF emissions (very important for airplanes). It’s from Garmin. I ordered it today. In a week I’ll find out if it really is low emission.
Garmin High-speed Multi-charger

 

[n1chu]

Thanks for the research. RFI is a real problem in the aviation world... surprised no one had mentioned this before. (I guess I had simply missed it!) But now that you have brought it to our attention, I imagine there’s a “DO NOT USE” list out there somewhere in the aviation sector that lists both acceptable and unacceptable adapters... just have to find it!

 

[Benkasey]

I am pleased to report that the Garmin powerport which I purchased has eliminated the RF interference problem. Thank you Garmin!
Garmin High-speed Multi-charger

 

[n1chu]

Ah, that is good to hear. (I didn’t even give Garmin a thought but once you informed us of your research I was sure Garmin was a good bet for products the FAA would have no problem with.) My first thought was to simply try another brand of the device commonly sold in any store, check to see how it compared with the one you had, return it if not satisfied and try another, and so on and so on. I probably would have saved a few bucks if I got lucky with the first replacement I tried. Thanks for bringing that problem to my attention-I don’t have it but never would have considered it if I had!