You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
The Feb 2025 Radioddity Giveaway Results are In! Click Here to see who won!

Reply to thread

Message

There's your problem right there. In both cases you have effectively no RF ground. Sure you may have a good DC ground but you've no RF ground. Its metal under the antenna which matters, not what is alongside it. As a result your coax is being used as part of the antenna system and you get common mode RFI and one of the downsides of common mode RFI is noise ingress.

If you had a good RF ground you would find that you didn't get 1:1 SWR unless you cut a few inches off the antenna and with an antenna like a Wilson Silvertip that it was almost impossible to get 1:1. Stock antennas are sold at a length that works for poor RF grounds as most people are either using magmounts or mounts like you are.

I mount mine using a body mount in the middle of the roof of my car, the hood, hatchback and exhaust are all bonded to the main body of the car. Antenna analyser shows within an ohm of perfect impedance using a 1/4 wave whip. Every CB antenna I get I have to get a dremel out and cut a few inches off. I can run a pre-amp with the engine running and have S0 on the meter.

<blockquote data-quote="M0GVZ" data-source="post: 634454" data-attributes="member: 22312">There&#039;s your problem right there. In both cases you have effectively no RF ground. Sure you may have a good DC ground but you&#039;ve no RF ground. Its metal under the antenna which matters, not what is alongside it. As a result your coax is being used as part of the antenna system and you get common mode RFI and one of the downsides of common mode RFI is noise ingress.If you had a good RF ground you would find that you didn&#039;t get 1:1 SWR unless you cut a few inches off the antenna and with an antenna like a Wilson Silvertip that it was almost impossible to get 1:1. Stock antennas are sold at a length that works for poor RF grounds as most people are either using magmounts or mounts like you are. I mount mine using a body mount in the middle of the roof of my car, the hood, hatchback and exhaust are all bonded to the main body of the car. Antenna analyser shows within an ohm of perfect impedance using a 1/4 wave whip. Every CB antenna I get I have to get a dremel out and cut a few inches off. I can run a pre-amp with the engine running and have S0 on the meter.</blockquote>

[QUOTE="M0GVZ, post: 634454, member: 22312"] There's your problem right there. In both cases you have effectively no RF ground. Sure you may have a good DC ground but you've no RF ground. [B]Its metal under the antenna which matters[/B], not what is alongside it. As a result your coax is being used as part of the antenna system and you get common mode RFI and one of the downsides of common mode RFI is noise ingress. If you had a good RF ground you would find that you didn't get 1:1 SWR unless you cut a few inches off the antenna and with an antenna like a Wilson Silvertip that it was almost impossible to get 1:1. Stock antennas are sold at a length that works for poor RF grounds as most people are either using magmounts or mounts like you are. I mount mine using a body mount in the middle of the roof of my car, the hood, hatchback and exhaust are all bonded to the main body of the car. Antenna analyser shows within an ohm of perfect impedance using a 1/4 wave whip. Every CB antenna I get I have to get a dremel out and cut a few inches off. I can run a pre-amp with the engine running and have S0 on the meter. [/QUOTE]

Top Bottom