6 Meter Interference caused by TV Channel 2.
 

I’m experiencing some strong interference across the 6 meter band which
I believe is coming from a local (within 40 miles) TV channel 2. Where
can I get a filter to deal with this? Is there a low pass filter with
a cutoff at 54 MHz? I only work SSB and CW on 6 so I’m only interested
in the lower portion of the band, if I cut off 52 MHz and above that
would be fine by me…..

George

The most likely cuase is that your receiver front-end is broad enough
to pass the TV2 signal through the RF amplifier, and modulate everything
else being received.

It's difficult to get a low-pass or high-pass filter will a sharp enough
cut-off to do much good. Better solutions are to build a notch filter for
the TV2 video carrier at 55.25 MHz (using a T-connector and a length
of coax trimmed to length, or to buy or build a passband filter for
50-52 MHz.

I had this problem with channel 11 and a 220 MHz receiver, and ended
up building a bandpass filter with a pair of coupled LC tanks, tapped at
50 ohms. Totally eliminated the TV cross-modulation problems.

-- Tom




"GeorgeF" wrote in message
nk.net...
I’m experiencing some strong interference across the 6 meter band which I
believe is coming from a local (within 40 miles) TV channel 2. Where can
I get a filter to deal with this? Is there a low pass filter with a
cutoff at 54 MHz? I only work SSB and CW on 6 so I’m only interested in
the lower portion of the band, if I cut off 52 MHz and above that would be
fine by me…..

George

The most likely cuase is that your receiver front-end is broad enough
to pass the TV2 signal through the RF amplifier, and modulate everything
else being received.

It's difficult to get a low-pass or high-pass filter will a sharp enough
cut-off to do much good. Better solutions are to build a notch filter for
the TV2 video carrier at 55.25 MHz (using a T-connector and a length
of coax trimmed to length, or to buy or build a passband filter for
50-52 MHz.

I had this problem with channel 11 and a 220 MHz receiver, and ended
up building a bandpass filter with a pair of coupled LC tanks, tapped at
50 ohms. Totally eliminated the TV cross-modulation problems.

-- Tom




"GeorgeF" wrote in message
nk.net...
I’m experiencing some strong interference across the 6 meter band which I
believe is coming from a local (within 40 miles) TV channel 2. Where can
I get a filter to deal with this? Is there a low pass filter with a
cutoff at 54 MHz? I only work SSB and CW on 6 so I’m only interested in
the lower portion of the band, if I cut off 52 MHz and above that would be
fine by me…..

George

The most likely cuase is that your receiver front-end is broad enough
to pass the TV2 signal through the RF amplifier, and modulate everything
else being received.

It's difficult to get a low-pass or high-pass filter will a sharp enough
cut-off to do much good. Better solutions are to build a notch filter for
the TV2 video carrier at 55.25 MHz (using a T-connector and a length
of coax trimmed to length, or to buy or build a passband filter for
50-52 MHz.

I had this problem with channel 11 and a 220 MHz receiver, and ended
up building a bandpass filter with a pair of coupled LC tanks, tapped at
50 ohms. Totally eliminated the TV cross-modulation problems.

-- Tom




"GeorgeF" wrote in message
nk.net...
I’m experiencing some strong interference across the 6 meter band which I
believe is coming from a local (within 40 miles) TV channel 2. Where can
I get a filter to deal with this? Is there a low pass filter with a
cutoff at 54 MHz? I only work SSB and CW on 6 so I’m only interested in
the lower portion of the band, if I cut off 52 MHz and above that would be
fine by me…..

George

I’m experiencing some strong interference across the 6 meter band which
I believe is coming from a local (within 40 miles) TV channel 2.

George-

What is the nature of your interference, and what type of equipment are you
using? Can you observe anything in the interference that can be corelated to
audio or video activity on the TV channel?

I live about that distance from a channel 2 TV station. Although I don't have
a beam, I have never had any trouble that could be blamed on the TV station.
In addition to SSB, I operate on several FM repeaters with output as high as
53.330 MHz.

I have used a Kenwood TS-670, TS-690 and Icom IC-706, both mobile and at home
with a dipole. Their front ends and IF filters seem to be quite adequate to
reduce the TV signal, even when driving closer to the station.

The only problems other than from occasional power line noise, has been when
driving past establishments with computerized cash registers or test equipment.
Once I received interference from an experimental radar system that overloaded
the front end of the IC-706. It generated intermodulation spurs about every
KHz, corresponding to a pulse repitition rate of 1000 pps. In all cases, the
interference subsided after driving away from the source.

73, Fred, K4DII

I’m experiencing some strong interference across the 6 meter band which
I believe is coming from a local (within 40 miles) TV channel 2.

George-

What is the nature of your interference, and what type of equipment are you
using? Can you observe anything in the interference that can be corelated to
audio or video activity on the TV channel?

I live about that distance from a channel 2 TV station. Although I don't have
a beam, I have never had any trouble that could be blamed on the TV station.
In addition to SSB, I operate on several FM repeaters with output as high as
53.330 MHz.

I have used a Kenwood TS-670, TS-690 and Icom IC-706, both mobile and at home
with a dipole. Their front ends and IF filters seem to be quite adequate to
reduce the TV signal, even when driving closer to the station.

The only problems other than from occasional power line noise, has been when
driving past establishments with computerized cash registers or test equipment.
Once I received interference from an experimental radar system that overloaded
the front end of the IC-706. It generated intermodulation spurs about every
KHz, corresponding to a pulse repitition rate of 1000 pps. In all cases, the
interference subsided after driving away from the source.

73, Fred, K4DII

I’m experiencing some strong interference across the 6 meter band which
I believe is coming from a local (within 40 miles) TV channel 2.

George-

What is the nature of your interference, and what type of equipment are you
using? Can you observe anything in the interference that can be corelated to
audio or video activity on the TV channel?

I live about that distance from a channel 2 TV station. Although I don't have
a beam, I have never had any trouble that could be blamed on the TV station.
In addition to SSB, I operate on several FM repeaters with output as high as
53.330 MHz.

I have used a Kenwood TS-670, TS-690 and Icom IC-706, both mobile and at home
with a dipole. Their front ends and IF filters seem to be quite adequate to
reduce the TV signal, even when driving closer to the station.

The only problems other than from occasional power line noise, has been when
driving past establishments with computerized cash registers or test equipment.
Once I received interference from an experimental radar system that overloaded
the front end of the IC-706. It generated intermodulation spurs about every
KHz, corresponding to a pulse repitition rate of 1000 pps. In all cases, the
interference subsided after driving away from the source.

73, Fred, K4DII

Tom wrote:
The most likely cuase is that your receiver front-end is broad enough
to pass the TV2 signal through the RF amplifier, and modulate everything
else being received.

It's difficult to get a low-pass or high-pass filter will a sharp enough
cut-off to do much good. Better solutions are to build a notch filter for
the TV2 video carrier at 55.25 MHz (using a T-connector and a length
of coax trimmed to length, or to buy or build a passband filter for
50-52 MHz.

I had this problem with channel 11 and a 220 MHz receiver, and ended
up building a bandpass filter with a pair of coupled LC tanks, tapped at
50 ohms. Totally eliminated the TV cross-modulation problems.



1) Where can one buy a passband filter for 50-52MHz?

2) When talking about coax trimmed to length, are you talking about a
coax stub? Such as cut to 1/4 wavelength of the offending freq? If so
would be ends be shorted or let open? never worked with stubs yet....

TNX
George

Tom wrote:
The most likely cuase is that your receiver front-end is broad enough
to pass the TV2 signal through the RF amplifier, and modulate everything
else being received.

It's difficult to get a low-pass or high-pass filter will a sharp enough
cut-off to do much good. Better solutions are to build a notch filter for
the TV2 video carrier at 55.25 MHz (using a T-connector and a length
of coax trimmed to length, or to buy or build a passband filter for
50-52 MHz.

I had this problem with channel 11 and a 220 MHz receiver, and ended
up building a bandpass filter with a pair of coupled LC tanks, tapped at
50 ohms. Totally eliminated the TV cross-modulation problems.



1) Where can one buy a passband filter for 50-52MHz?

2) When talking about coax trimmed to length, are you talking about a
coax stub? Such as cut to 1/4 wavelength of the offending freq? If so
would be ends be shorted or let open? never worked with stubs yet....

TNX
George

Tom wrote:
The most likely cuase is that your receiver front-end is broad enough
to pass the TV2 signal through the RF amplifier, and modulate everything
else being received.

It's difficult to get a low-pass or high-pass filter will a sharp enough
cut-off to do much good. Better solutions are to build a notch filter for
the TV2 video carrier at 55.25 MHz (using a T-connector and a length
of coax trimmed to length, or to buy or build a passband filter for
50-52 MHz.

I had this problem with channel 11 and a 220 MHz receiver, and ended
up building a bandpass filter with a pair of coupled LC tanks, tapped at
50 ohms. Totally eliminated the TV cross-modulation problems.



1) Where can one buy a passband filter for 50-52MHz?

2) When talking about coax trimmed to length, are you talking about a
coax stub? Such as cut to 1/4 wavelength of the offending freq? If so
would be ends be shorted or let open? never worked with stubs yet....

TNX
George