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Author Topic: 40m RFI issues inside vehicle  (Read 2781 times)
AB1PJ
Member

Posts: 33




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« on: May 20, 2012, 06:54:57 AM »

I have 40m RFI issues inside the RV (motorhome) when transmitting
I use a Ameritron ALS500 linear amplifier
This is observed during CW or DIGITAL or SSB

1. 12V car audio speakers - cycles on/off when i xmit

2. 12V water pump - cycles on/off when i xmit

3. 12V refrigerator - cycles on/off when i xmit

4. 12V air conditioning thermostat - cycles 110VAC on/off

In an attempt to fix this
I installed snap on chokes (from http://www.radiodan.com/Henry/parts/RF_chokes.htm) with two turns of both speaker wires. Still RFI....

I haven't done that for other 12V appliances.

What else could i do?
Did i not select the correct RFI?
Do i need more chokes or more turns of wire inside the choke?

Anything else?

thanks
jim


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NO2A
Member

Posts: 758




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« Reply #1 on: May 22, 2012, 07:48:20 PM »

You could try running the coax through a ferrite core choke. That`s a tough one Jim,the close antenna,qro,etc. Do you still get the rfi at the 100 watt level?
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K5LXP
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Posts: 4448


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« Reply #2 on: May 22, 2012, 08:15:41 PM »

With this many affected devices, we're talking about a lot of RF floating around.  There's only so much ferrites will do with a high level of incident RF.

What's the antenna?   Your fix may lie there.


Mark K5LXP
Albuquerque, NM
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AB1PJ
Member

Posts: 33




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« Reply #3 on: May 22, 2012, 08:23:20 PM »

Antenna is a 33' vertical wire on a winsock pole, raised 13' above ground, at the rear of the
vehicle above the roof attached to the rear ladder with clamp (ladder is not connected to antenna)

I have a 4:1 voltage balun at the base of antenna so that the tuner inside the shack doesn't have to
work that hard. I ran a 50' coax LMR 400 inside the shack and have an LDG1kW tuner, Ameritron ALS500
connected to my Flex 3000.

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K5LXP
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Posts: 4448


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« Reply #4 on: May 23, 2012, 07:52:22 AM »

Antenna is a 33' vertical wire on a winsock pole, raised 13' above ground, at the rear of the vehicle above the roof attached to the rear ladder with clamp (ladder is not connected to antenna)

What are you using for radials?


Mark K5LXP
Albuquerque, NM
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AB1PJ
Member

Posts: 33




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« Reply #5 on: May 23, 2012, 08:03:57 AM »

I ran a 1" braided ground wire to the frame of the vehicle. The braided cable is about 10' long
since the antenna is above the roofline and chassis frame ground is towards bottom of vehicle.

It is a http://www.monacocoach.com/StaticFiles/monaco/images/product%20pages/signature/signature_Chasis.jpgso there is plenty of metal in it (albeit not like Cu radial wires spread like
a fan).

How may i improve this?
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