2m noise when receiving

[zero_frequency]

Hi,

I am having problems on 2m simplex (146.52) where the other station can hear me fine, but I cannot hear them clearly. I have a K3s with a Diamond V2000A on a temporary U213 cable 50' away. I believe the problem is on my end because the other end has no issues at all making contacts.

What's happening is, there is no noise on the 2m band. Then I hear the station transmitting, but it's very difficult to make out what is being said because of all the noise which is heard only when the other station is transmitting.

I've adjusted my RF SQL which seems to help the further up I turn it, but still not enough to clear up the noise.

Thoughts?

 

[hill]

Most likely he is just to far away from you.

You would need to raise you antenna height a lot. Maybe to get better coax or have a shorter run of coax, since a lot of the received signal is being lost in coax before it even reaches your radio.

 

[vagrant]

- I think you meant KX3, which offers 10W max. If the station can hear your 10W, or less, you’re probably close enough to hear him.

- Your antenna and coax are probably fine as well, since they can receive you.

- The “no noise” is the concern. You should hear plenty of noise/static when no one is talking. Press the knob on the far left to adjust the RF gain. Turn the dial clockwise all the way. You should hear static. If not, press the far left knob again to now adjust the volume level.

- Ensure the radio is set to FM and not SSB.

- Additionally/Alternatively, you may have RFI issues from a nearby transmitter.

 

[AK9R]

The only K3S that I know of is from Elecraft and is a 160 meter through 6 meter transceiver. In order to receive 2 meters, it needs the K144XV option. Do you have that option?

 

[K9KLC]

I have a K3s

How about telling us what radio you actually have or perhaps a little more about your station.

 

[zero_frequency]

Most likely he is just to far away from you.

You would need to raise you antenna height a lot. Maybe to get better coax or have a shorter run of coax, since a lot of the received signal is being lost in coax before it even reaches your radio.

He is four miles away.

 

[zero_frequency]

How about telling us what radio you actually have or perhaps a little more about your station.

I have a K3s.

 

[zero_frequency]

The only K3S that I know of is from Elecraft and is a 160 meter through 6 meter transceiver. In order to receive 2 meters, it needs the K144XV option. Do you have that option?

Hi AK9R, yes, it's a K3s with a K144XV.

 

[zero_frequency]

- I think you meant KX3, which offers 10W max. If the station can hear your 10W, or less, you’re probably close enough to hear him.

- Your antenna and coax are probably fine as well, since they can receive you.

It's new U213 from dxengineering.

- The “no noise” is the concern. You should hear plenty of noise/static when no one is talking. Press the knob on the far left to adjust the RF gain. Turn the dial clockwise all the way. You should hear static. If not, press the far left knob again to now adjust the volume level.

Even on VHF? I get that on HF where there's a noise floor. And I'm specifically asking about the noise only when transmitting which is not the noise floor. I'll look into why no noise if you're saying there should be a noise floor on VHF.

- Ensure the radio is set to FM and not SSB.

Checked, FM.

- Additionally/Alternatively, you may have RFI issues from a nearby transmitter.

The nearest transmitters I know of are cell towers about 5 miles away. I'm pretty much out in nowhere's in central texas.

 

[K9KLC]

I'll look into why no noise if you're saying there should be a noise floor on VHF.

if you open the squelch all the way you're not hearing noise?

 

[chief21]

What's happening is, there is no noise on the 2m band. Then I hear the station transmitting, but it's very difficult to make out what is being said because of all the noise which is heard only when the other station is transmitting.

It sounds as if there might be some device in (or near) your location that is creating interference. There are lots of household devices that are considered "unintentional emitters"... devices that can emit RF, and some of them can be extremely wide-band.
Check things like TV sets, wifi routers, inexpensive power supplies (wall-warts), and even newer washing machines with on-board electronics! Certain types of lighting are known to create RF issues. I have a tankless water heater that occasionally interferes with certain VHF-FM frequencies.
You can find recommended procedures for tracking down such signals online, but it can be difficult and time-consuming.

 

[KE5MC]

I have a K3 not K3s nor do I have the 2m module. I'll throw this idea into the mix... On the display in the lower left corner is the bandwidth/shift display icon. It looks like a rectangle sitting on a horizontal line and with FP controls the left and right edges can be move farther or closer together (bandwidth) or moved up and down the bandwidth (shift). I have used my K3 in FM at the top of the 10m band, but don't really recall what the response is to bandwidth/shift if set narrowly and pushed to the top or bottom of the bandwidth. For sideband operation easy to adjust received audio to improve intelligence or go to far and degrade the signal. Likely same impact for FM, but not sure.

The K3 and K3s both have an extensive setup and without going back to the manual and researching there is setup for 'roof-filters', modes, and bands. I'm thinking the received audio path via the 2m path might need a look at.

73, Mike

P.S. While I'm thinking about it the RF/SQL knob is a shared function which kicks in for FM. Again without taking time to sit at the radio and figure it out I think SQL is the primary function in FM, but don't recall how to adjust RF gain. :-(

 

[MTS2000des]

A low cost SDR or spec an will show you your noise floor and has been mentioned, the modern residential landscape is now filled with "unintentional radiators" that, thanks to a lack of enforced engineering standards limiting spurious RFI, and thus the noise floor on much of the RF spectra is filled with hash and trash that can impair otherwise usable RF signal sources. When your noise floor at your receiver sits at -90dbm and your station 4 miles away is coming to you at -100dbm, you get nothing.

 

[zero_frequency]

I did revisit all the ideas brought up, so thanks for those. I completely reinstalled everything, swapped the U213 & RG-8X for a single 100' line of 400, replaced the antenna with a dual-band J-pole, and was also able to raise it up about 10'. Replaced everything but the transceiver.. The noise is gone. Thanks again.