EOT hum. Commercial repeater

[KI7JLK]

The company I work for recently purchased a Hytera digital/analog repeater from a dealer for the analog VHF communications at our remote Alaskan work site. There's is an annoying End Of Transmission hum/tone (that our crew describes as flatulence). Occasionally the tone, which sounds like a 60hz hum, is unheard. Sometimes it's quite loud, but it varies in amplitude and is present on most every transmission. On the advice of our dealer, radio PTT ID's have been changed from DTMF to Fleetsync in an attempt to eliminate the EOT hum on our radios. This has not worked. We do not program radio ID's.

I had to re-flash a few radios to eliminate the repeater ID tone as well. We use TK 2160 and 2360 handhelds and 7302 fixed stations. A 7150 will hear the repeater ID no matter how many times I put in the CTCSS tone.

Is this a tone that's been programmed into the radios or repeater, or a 60 hz hum from a bad transformer in the area?

Here's what I've tried.
1. The repeater is grounded with #6 bare copper to a dedicated ground rod.
2. The power supply has been moved away from the repeater
3. A ferrite attached to the DC supply at the power supply
4. 18" wire attached to the DC- at power supply

The antenna and coax are not close to any AC lines, and the repeater is in a dedicated rack in a room without any other electronics.

Thanks

 

[mmckenna]

Which CTCSS tone are you using?

 

[12dbsinad]

My bet is a problem with the repeater power supply

 

[12dbsinad]

Or a really high CTCSS tone is being used

 

[kd4efm]

The other question is, desense been check on the BpBr? Possible the combiner needs to retuned?

 

[FKimble]

AS already asked: what tone are you using? Some are in the range that can be heard!

Frank

 

[KI7JLK]

Which CTCSS tone are you using?

136.5 in and out

 

[KI7JLK]

My bet is a problem with the repeater power supply

The power supply has a battery backup option. I'll try killing the AC and see if it does it on battery.

 

[mmckenna]

136.5 in and out

That's usually not high enough to come through on the audio. I used 254.1Hz once on a system I had access to and it was high enough to come through as a low rumble in the audio if you didn't have the audio pass filters set.

My money is starting to go on the power supply.

 

[wd8chl]

The company I work for recently purchased a Hytera digital/analog repeater from a dealer for the analog VHF communications at our remote Alaskan work site.

My condolences.

There's is an annoying End Of Transmission hum/tone (that our crew describes as flatulence). Occasionally the tone, which sounds like a 60hz hum, is unheard. Sometimes it's quite loud, but it varies in amplitude and is present on most every transmission. On the advice of our dealer, radio PTT ID's have been changed from DTMF to Fleetsync in an attempt to eliminate the EOT hum on our radios. This has not worked. We do not program radio ID's.

I had to re-flash a few radios to eliminate the repeater ID tone as well. We use TK 2160 and 2360 handhelds and 7302 fixed stations. A 7150 will hear the repeater ID no matter how many times I put in the CTCSS tone.

Is this a tone that's been programmed into the radios or repeater, or a 60 hz hum from a bad transformer in the area?

Here's what I've tried.
1. The repeater is grounded with #6 bare copper to a dedicated ground rod.
2. The power supply has been moved away from the repeater
3. A ferrite attached to the DC supply at the power supply
4. 18" wire attached to the DC- at power supply

The antenna and coax are not close to any AC lines, and the repeater is in a dedicated rack in a room without any other electronics.

Thanks

I ran across that a few years ago. It's a firmware problem. Find and update to newer firmware, but you'll probably have to find the new software as well. After the Motorola lawsuit, HYT had to completely change all of their firmware and software to get rid of the disputed code. The hum problem was something that got fixed about that time. The software and firmware are what they call the "i-series".

 

[Project25_MASTR]

Dedicated ground rod (assuming it's not bonded to service ground) could also be inducing the hum...

In this case, it's likely more cost (and time) effective to have an experienced radio tech diagnose it.