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RF noise

Dec 15th 2019, 19:53

focus

Joined: Dec 15th 2019, 18:21
Total Topics: 0
Total Posts: 0
I have only had my license one month so if my questions sound dumb, so be it.

I have an old Kenwood TS 130 radio with a 50 foot inverted V antenna. I have been able to make several contacts in the last week on 40 and 20 meters but sometime the "static" is louder than the signal. Is this normal? or do I need to place a choke somewhere to eliminate some of the noise?
My swr is 1.2:1 on 40 and 1.29:1 on 20 (i have built a 40/20 fan antenna) Any help would be appreciated> Thank you W6NNN
Dec 16th 2019, 15:16

W1VT

Super Moderator

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
It is possible to have common mode noise that will impair reception that can be eliminated with a choke. I noticed that when I started my logging program the noise level would increase on two different antennas. Careful inspection revealed that neither antenna had a balun--the feedline was directly connected to one half of the dipole. Adding a balun to each antenna fixed the problem--I could log contacts without hearing noise from the computer.

An effective way to determine whether a choke will help is to run a receiver off a battery and shut the main breaker of the house to turn off all the electrical devices in the house at once. You can miss stuff if you turn off one breaker at a time if devices generating the same noise are on more than one circuit.

Zak W1VT
ARRL Senior Lab Engineer

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