# Filtering VHF FM on my DTV signal

I've noticed that when I transmit on my HT when I'm watching TV (OTA), the signal drops and the screen goes blank (or digital "static") and then returns when I stop. I've replicated the issue by artificially causing a signal loss on the TV by either covering the antenna or disconnecting it.

Right now it's annoying, however, my intention is to mount the antenna (it's an outdoor Omni that I've been lazy and haven't mounted and run cable for) and it will then be within 30 feet horizontally of my VHF base station antenna. My concern is that I could burn out the TV or amp (built into the antenna) when on a net. I've never tested to see if the TV is currently impacted by my base station, the TV is downstairs, Radio is upstairs, which makes observation difficult.

I imagine I need some sort of band pass filter, but I'm not having any luck with my Google-Fu. Am I overly concerned? Do you have any specific or general recommendations?

Links: TV Antenna: Amplified Outdoor Antenna with Omni-directional

Base Station: Moto XPR5550e VHF 50w

Base Station Antenna: Diamond X50A

• When you say the amplifier is built into the antenna, are you sure about that? The description on the page you linked says "detachable amplifier" — it could be a misdescribed bias-tee but that seems less likely than the reverse. This matters because it determines whether you can insert a filter before the amplifier. (Please edit your question to clarify this.) – Kevin Reid AG6YO May 2 '17 at 15:38
• Also, it might be worth experimenting to figure out whether the HT is interfering with the TV by way of the antenna input or the chassis of the TV. That is, spread apart the TV and antenna as far as you can, transmit at low power (or better yet into a dummy load which will leak) near the TV and near the antenna and see which interferes more. This helps you figure whether it matters that you're moving the antenna. – Kevin Reid AG6YO May 2 '17 at 15:41
• Good question! I had assumed it was like my old Yagi that I had and the powered part was an injector that powered a mast head amp. I'll look at it closer and update when I get home later this afternoon. – Kerry Hatcher May 2 '17 at 17:25
• Which frequencies are you transmitting on and which TV channels are dropping when this happens? – AG5CI Jun 6 '17 at 17:59

You are probably just desensitizing the receiver in the TV or the amplifier. What you need is a band-stop filter that covers the band you're transmitting on with your HT (144-148 I assume?). Place it between the antenna and amplifier or amplifier and TV to see which is being desensitized.

I've never tested to see if the TV is currently impacted by my base station, the TV is downstairs, Radio is upstairs, which makes observation difficult.

If you have a smart phone or video camera, set it up to look at and record the TV while you go upstairs and transmit.

• Welcome to ham.stackexchange.com, Paul! Please consider taking the tour to get the most from the site. – Mike Waters Jun 5 '17 at 1:56