Tx powers off devices in car

[CapNBall]

I was driving around this morning trying to see if I could hit some repeaters in the area. I have an aftermarket phone interface in the car (search "carplay screen" on Amazon for an idea...). I noticed that every time I keyed the mic on the HT, the carplay screen would turn off, including the red light where the power cord plugs into the 12v. I don't know enough about electronics to know how to isolate if the RF signal is somehow disconnecting the power supply and the unit is losing power or if it's the electronics inside shutting down either via protective circuitry or just being overwhelmed. The device uses Bluetooth and has an FM transmitter, but neither of those are close to GMRS frequencies. But maybe just 5 watts at any frequency is too much that close to the device?

I'm curious about the mechanism, but more importantly looking for a solution. Would an external antenna mounted further back on the car help? Is there any kind of shielding that can be done while still allowing the Bluetooth and FM to work? Something else altogether?

[tweiss3]

An external antenna would probably remedy your solution over an HT in the car. Doesn't matter if it's the same frequency, other electronics tend to not like transmitting anything near them. Computer screens, computer speakers, etc. all complain when even 2W of VHF, UHF or 6meters is transmitted within a few feet.

[WRTC928]

1 hour ago, tweiss3 said:

An external antenna would probably remedy your solution over an HT in the car. 

As a bonus, a simple magnetic mount antenna on the roof will give you significantly -- sometimes dramatically -- improved range and clarity over using a stock antenna inside the vehicle (aka Faraday cage). However, if you're going to regularly use the radio with an external antenna, I recommend you get a BNC adapter to reduce strain on the SMA connector. You'll also need a BNC to SO239 adapter to attach the radio to the antenna. SMA connectors weren't designed to have antennas screwed and unscrewed too many times and they can break with frequent use. BNC connectors were made specifically for a great many antenna swaps. 

I have BNC adapters on all the radios I use frequently so I can quickly change the antenna according to the mission. For example, most of the time, I can use my favorite repeater with an 8" antenna, but if I'm going to be a little further away, I change to a 15" whip. There's a 1.25 meter repeater in Oklahoma City, but I can't reach it from my usual places, although I do go there sometimes. I don't want to have a 17" antenna on my HT all the time, so I can quickly swap the shorter antenna for a tri-band when I'm near the city.

[WRTC928]

42 minutes ago, CapNBall said:

There are so many connector types, it still gets confusing.

Yeah, I had a lot of false starts before I got it figured out.  I figured I'd try to make it simpler for others. I don't know if your radio has a male SMA connector (like a Baofeng) or a female one (like a Retevis). Be sure you order the right adapter. Either way, you want to change it to a female BNC connector.

[CapNBall]

8 hours ago, tweiss3 said:

An external antenna would probably remedy your solution over an HT in the car. Doesn't matter if it's the same frequency, other electronics tend to not like transmitting anything near them. Computer screens, computer speakers, etc. all complain when even 2W of VHF, UHF or 6meters is transmitted within a few feet.

I ordered one to give it a try. I was wanting to get one anyway, hopefully that takes care of it! Thanks!

 

6 hours ago, WRTC928 said:

As a bonus, a simple magnetic mount antenna on the roof will give you significantly -- sometimes dramatically -- improved range and clarity over using a stock antenna inside the vehicle (aka Faraday cage). However, if you're going to regularly use the radio with an external antenna, I recommend you get a BNC adapter to reduce strain on the SMA connector. You'll also need a BNC to SO239 adapter to attach the radio to the antenna. SMA connectors weren't designed to have antennas screwed and unscrewed too many times and they can break with frequent use. BNC connectors were made specifically for a great many antenna swaps. 

I have BNC adapters on all the radios I use frequently so I can quickly change the antenna according to the mission. For example, most of the time, I can use my favorite repeater with an 8" antenna, but if I'm going to be a little further away, I change to a 15" whip. There's a 1.25 meter repeater in Oklahoma City, but I can't reach it from my usual places, although I do go there sometimes. I don't want to have a 17" antenna on my HT all the time, so I can quickly swap the shorter antenna for a tri-band when I'm near the city.

Thanks for the links for the adapters! There are so many connector types, it still gets confusing.

[SteveShannon]

Just now, WRTC928 said:

Yeah, I had a lot of false starts before I got it figured out.  I figured I'd try to make it simpler for others. I don't know if your radio has a male SMA connector (like a Baofeng) or a female one (like a Retevis). Be sure you order the right adapter. Either way, you want to change it to a female BNC connector.

To make it worse, SMA connectors have 4 different genders: male thread and male center pin, male thread and female center socket, female thread and female center socket, and female thread and male center pin. 

[WRTC928]

6 minutes ago, SteveShannon said:

To make it worse, SMA connectors have 4 different genders: male thread and male center pin, male thread and female center socket, female thread and female center socket, and female thread and male center pin. 

True, but the male thread/male center pin and female thread/female center socket don't seem to be used much, at least not on inexpensive Chinese HTs.

[SteveShannon]

11 minutes ago, WRTC928 said:

True, but the male thread/male center pin and female thread/female center socket don't seem to be used much, at least not on inexpensive Chinese HTs.

Agreed.  For my handheld radios all of the cheapest ones use female threads and male pins. My expensive ones all use male threads and female center sockets. 

[CapNBall]

45 minutes ago, SteveShannon said:

To make it worse, SMA connectors have 4 different genders: male thread and male center pin, male thread and female center socket, female thread and female center socket, and female thread and male center pin. 

I'm pretty sure I got the right one. If not, I'll have learned something and also have more parts in my box of trinkets that may be useful later (aka, stuff my kids will have to haul to the landfill when I die).

[WRTC928]

21 hours ago, SteveShannon said:

Agreed.  For my handheld radios all of the cheapest ones use female threads and male pins. My expensive ones all use male threads and female center sockets. 

All the ones I use much now have BNC connectors installed. I can use any antenna on any radio, and I don't worry about breaking the SMA connector.