Kenwood: TM-V71A interfering with scanner

KE0GXN · May 27, 2016

I noticed today whenever I key the mike on my radio, it cuts off all transmissions on my Home Patrol II. Not a major issue as it obviously prevents PS traffic from being broadcasted via background noise on the amateur bands, however I keep the scanner volume pretty low, so I doubt it will ever be an issue. With said I would still rather be able to hear my scanner when I am talking on my Kenwood.

I have tried separating the antenna feed lines as far away from each other as possible to no avail. The scanner's antenna is mounted on the same outdoor mast approximately 2 feet below the base of my 2m/70cm antenna.

Anybody know of fix for this or why its happening?

Kb2Jpd · May 27, 2016

KE0GXN said:
I noticed today whenever I key the mike on my radio, it cuts off all transmissions on my Home Patrol II. Not a major issue as it obviously prevents PS traffic from being broadcasted via background noise on the amateur bands, however I keep the scanner volume pretty low, so I doubt it will ever be an issue. With said I would still rather be able to hear my scanner when I am talking on my Kenwood.

I have tried separating the antenna feed lines as far away from each other as possible to avail. The scanner's antenna in mounted on the same outdoor mast approximately 2 feet below the base of my 2m/70cm antenna.

Anybody know of fix for this or why its happening?

Use minimum amount of power necessary.

Your cutting out is because you are either saturated the RF end or if it has protection diodes, there is enough RF voltage that the diodes work by conduction and short out the front end.

Are all the frequency on scanner affected or just adjacent frequency? If you are just listening to UHF or Vhf, you might want to purchase a bandpass filter.

Adam Kb2Jpd

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KE0GXN · May 27, 2016

The frequencies I noticed that were affected were a 800mhz trunked system and a VHF P-25 P2 system.

I do listen to both conventional PS VHF and UHF frequencies too. However, I have not had the chance to see if it cuts those off too.

I'll try changing the power setings and see if that helps.

*edit*

Power setting did not matter. Even at 5 watts it cut off all scanner transmissions....

N4KVE · May 27, 2016

Scanners are so open to receive everything they have no selectivity. Nothing you can do except seperate the antennas more.

Kb2Jpd · May 27, 2016

MOONBOOTS said:
Scanners are so open to receive everything they have no selectivity. Nothing you can do except seperate the antennas more.

You can do more. But you will need to give more info. Sometimes it's as simple as you listening to your harmonic or mixed harmonics thanks to powerful nearby transmitters. Other times, you might have stuff inline that is affected by your own transmission S.

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cmdrwill · May 27, 2016

KE0GXN said:
snip The scanner's antenna is mounted on the same outdoor mast approximately 2 feet below the base of my 2m/70cm antenna.

There IS your problem, Sir.

KE0GXN · May 27, 2016

MOONBOOTS said:
Scanners are so open to receive everything they have no selectivity. Nothing you can do except seperate the antennas more.

I'll see what I can do with the antennas.

Thanks.

KE0GXN · May 27, 2016

cmdrwill said:
There IS your problem, Sir.

Yeah, it looks that way. I'll try and see what I can do about removing the scanner antenna off the mast but still keeping it outdoors.

Thanks for the feedback.

KE0GXN · May 28, 2016

Problem solved! Moved the scanner antenna off the 2m/70cm mast.

Thanks for all the help guys!

Kb2Jpd · May 28, 2016

KE0GXN said:
Problem solved! Moved the scanner antenna off the 2m/70cm mast.

Thanks for all the help guys!

Good now be safe and get grounded for the summer weather.

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Kenwood: TM-V71A interfering with scanner

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