Help, strange signal drop out

See the video. This happens on both bands, any frequency. It comes and goes, seems to be worse in the morning but I don’t have any data stored support that. Last time it happened I parked my truck and turned it off so probably not any interference from my truck. It’s not always visible in the video but the RX completely drops when the audio drops. It’s just a slight flicker in the green bar.

This is a Yaesu FTM-400 on a COMPACTenna in my '21 RAM 1500

dont see a way to upload a video so here’s a link

1 Like

Can you adjust your squelch any lower? Seems like that might help.

1 Like

Negative. Squelch was at 1, even zero doesn’t help. The signal is strong

1 Like

Also, if I turn the radio off and back on it goes away for about one minute

1 Like

A couple of thoughts. Are you running APRS on 2 meters? If so, if the signal is going out every few seconds, it could be wiping out the receive end. Another thought? Does this happen no matter where you are? If it’s primarily one location, it could be a data transmitter on another frequency mixing in your receiver and taking out the receive end on 162.550. Do you notice this problem when monitoring repeaters and people are talking?

I do run APRS on the sub band but I have tried with that off too. I can hear the beacon go out and I see the tx signal. It happens over about a 10+ mile area around my house. I haven’t been farther since I discovered this.

It happens on both 2m and 70cm off and on, with various frequencies and repeaters. I had my HT in the truck with me earlier and the HT was fine. It’s a FT5D. I have an email out to Yaesu as well. :crossed_fingers:

1 Like

I have a video of it happening on out local clubs repeater, I just felt weird posting someone’s conversation so I used WX instead

Gotcha. I would rule out your vehicle if it only happens within 10 miles. That leads me to believe it’s RF. If you have a frequency meter, it might pay off trying to drive around and see if you get hits that might help figure it out. It seems to be a pulse signal that goes out every second or so. There are so many things that it could be, but most of those are low power. What I am guessing it could be is the signal of the interfering transmitter is mixing with your receiver’s IF. But then again, if you are getting this on other signals, that makes no sense. Hmmmm…sorry for thinking out loud. If you are only receiving this within a 10-mile or so radius of your house, that leads me to believe it is RF. It’s got to be a signal that also is strong enough to overcome the 500- or 1,000-watt signal of the NOAA transmitter.

Check the specs for the IF of both your handheld and mobile radio. I am guessing they are different. If they are the same, then maybe it is something within your vehicle that the wiring is picking up and maybe there is some signal your vehicle is sending out (such as the ON-STAR, wifi, etc., that is on board many vehicles today). However, I have never heard of such RFI, but gotta eliminate possibilities. Something is sending out an RF signal within that 10-mile or so radius and I’d be more willing to doubt it is within your vehicle than external.

If you have a local ham with a frequency meter, it might be a good idea to do some RF sniffing around the vehicle and see if there is a pulse signal going out.

But now I have another idea! Did you perhaps enable the PRIORITY switch on the radio (or whatever it might be called or in a menu)?

I am thinking now after typing all this that the radio is in priority mode, so it is sampling another frequency for traffic and if it receives traffic on that frequency, it locks on it. You could have a dud frequency in the priority frequency that never gets traffic and that’s why it never locks on it. See if you can check that, because right now, I am betting 95 percent that’s where the issue is. Especially if you encounter it on all frequencies. But why it only happens within 10 miles, that’s the part that makes this an only 95 percent solution.

Another thought … you don’t have one of the old LoJack transmitters on your vehicle for theft, do you? These send out a signal on 173.075 MHz, as I recall, and perhaps if it’s outside the range of old LoJack receivers (if they even still exist), the transmitter on board the vehicle shuts off because it is looking for the base transmitter to poll it. Just still thinking!

You might be onto something with Priority. I have used dual watch and I can see the freq change when it checks. I do know I have one memory set as priority but have no idea how to undo that from the radio.

Also, as if this were not strange enough. The issue goes away completely while I’m in the setup menu and comes back as soon as I close it.

That narrows it down to the radio, hopefully it’s a config and not an RMA

I will update once I get back to my PC


So there is a “priority channel” but you can’t disable or delete it, it’s just there. I’m not sure what it is for because it only shows up in the RTS software and not in the manual. There is a Dual Watch function that will monitor the “home” freq. but that is not what is happening. When that is on I can see the frequency change every few seconds when it is monitoring.

It might happen more than 10 miles away but since I work from home I just haven’t been farther in the past week lol. Of course I went out this evening and it was fine the entire time so who knows. Maybe Yaesu will respond, I don’t know what their support is like.

1 Like

Yeah, if you are seeing the frequency change, it definitely is a priority channel that it is sampling every second. I never use this on ham gear, but I do on scanners. Most of my scanners around the house are set up to priority sample the NOAA weather channel for FIPS SAME alerts. It keeps checking the weather channel every secondish to see if there is an alert. You can see it do the quick sample and the audio drops out (a little quicker than the interval on your rig). Yaesu support or even a Yaesu group online should be able to serve up some answers. I’m sure it’s a setting you can change.

Dual watch shouldn’t have anything to do with it because both receive sides are active at all times. Keep us posted as to what you find out. 73

Just to clarify, if I use Dual Watch I see the frequency change but I dont use that feature.

Not a lot to update. I did a factory reset and it seemed okay but it is intermittent so who knows. I reloaded my config and it did act up again but was great all day yesterday. I thought for a minute that simply turning off the APRS Modem was helping but it’s so hard to say.

Yaesu support hasn’t bothered to respond. I just may call HRO where I bought it.

1 Like

Unfortunately, most businesses find it tough to offer any type of support today (our business excepted!). I see people complaining left and right about ham radio businesses that don’t have the support in reasonable time frames, if not even bothering to answer. My suggestion would be to find a Yaesu-specific listserv or group online where you can get a crowdsourced response. I’m guessing there probably is an FTM-400-specific listserv on where you’ll get a bunch of responses. Hope you can get a solid answer!

1 Like