Troubleshooting Vhf and interference

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Stuart Baak
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Troubleshooting Vhf and interference

Post by Stuart Baak »

Hi guys,

I got myself a vhf radio, and installed it myself (very easy btw, took me just over an hour.)

Now, I have an issue. I was initially running with the Zara 130 antenna (long one) but due to the height, I can't fit at work... (I scrape along the roof and hit pipes etc, which is no good.)

So I put my Zara 60 on, but as soon as I do this and want to transmit, I get interference with my normal head unit radio. I have an amplifier in the car which obviously has an effect. How would I now sort this out? Anyone had this issue before? Even if I move the vhf radio as far away from the amp and head unit as possible, I can still hear the 'whine' interference :roll:

Help please!
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Re: Troubleshooting Vhf and interference

Post by JohanW »

I would start by running separate power lines to both radios and the battery. Is your 60 tuned/trimmed to the frequency you are transmitting at? It sounds to me like you getting a lot of power reflected back to the radio that the antenna is not able to effectively transmit. Get someone with a antenna tuner or a swr meter to look at your installation. If the 60 is really far out of tune you won't get a good reach with your transmission and risk burning out the radio. my 2c.
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Re: Troubleshooting Vhf and interference

Post by Stuart Baak »

Ya the Zara 60 was tuned to ORRA spec. The 'noise' only comes out of the car speakers, not the vhf radio itself.
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Re: Troubleshooting Vhf and interference

Post by Stuart Baak »

Spoke to some guys who do Vhf installs. They say it may be the continuity of the antenna. I'll troubleshoot that when I get home
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Re: Troubleshooting Vhf and interference

Post by zepplin »

How close to each other do antenna cables of both radios run?
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Re: Troubleshooting Vhf and interference

Post by Stuart Baak »

Not close at all at the moment. The FM radio antenna cable comes from the roof, and the vhf comes from the bonnet through the firewall to just behind the cubbie hole
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Re: Troubleshooting Vhf and interference

Post by Thunder02 »

The antenna must be tuned to the radio.
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Re: Troubleshooting Vhf and interference

Post by The Legend »

Make sure that the antenna whip lenght is correct. On the Zarra 60 (Orra channels) it is 47 cm measure from the flat base to the top of the whip.
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Re: Troubleshooting Vhf and interference

Post by Stuart Baak »

Thanks guys, for now, I have put the 130 back on and interference is gone. I'll double check my Zara 60 length and make the necessary adjustments (well, cut if need be or buy new one if I need it to grow)

Thanks for all input!
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Re: Troubleshooting Vhf and interference

Post by Family_Dog »

Stuart, are you only replacing the whip & coil when you change over from the Zara130 to the Zara60? Are you using the same antenna cable and connector but only changing the above?

The Zara130 has a coil and a long whip, the Zara60 comprises a spring and short whip, as Lollie states.

The symptoms sound like a dodgy antenna cable connection but this should be ruled out if you're making use of the same wiring harness and base mount.


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Stuart Baak
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Re: Troubleshooting Vhf and interference

Post by Stuart Baak »

Good morning uncle Eric! Yes I am just changing the whips and coils. The base cable remains unchanged. Tested the radio with my missus and my handheld, she heard me loud and clear from some distance away. I obviously couldn't hear her as well as she was transmitting from the 5w.
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