- September 27, 2016 at 8:17 pm #5540
I went to go on the air yesterday with my 7300 which has been doing really well.
When I got on 40m, the waterfall sees a lot of noise.
When I am recieving the s/po meter is always at 9 or in the red above.
I did some transmitting but I never got a response, when I transmit the S/po meter is at the top of the red marks
SWR seems ok though.
Did some setting in the radio get messed up?
I don’t see the noise on 20m but I have not tried to tramsit there.
I don’t think its the Antenna because when I put the Antenna Analyzer on the wires it gives the normal SWR I was getting for 1.0-1.5 on 20 and 40m.
I did add a footswitch and a headset with a microphone but that was working fine the last time I used.
Can anyone give me some pointers as to what I should look at to fix this?
Anthony RizzoloSeptember 28, 2016 at 10:08 am #5545
This is hard to answer without seeing the actual setup, but there are a few things you can try.
High Noise Level:
1) Listen on the offending band, and observe the background noise level with your S-meter.
2) Temporarily disconnect your antenna – your noise level should drop way down close to an S-meter S1 level. (try to prove the noise is not being generated by the radio)
3) Reconnect the antenna, the high noise level should return. (make sure the connection is good and secure).
4) Turn OFF the built-in Preamp and turn on the built in Attenuator. The noise level should be greatly reduced. Goal – don’t overdrive the front end of the radio with strong signal or background noise level. Don’t be afraid to use the attenuator or to adjust the front end gain controls when needed. If you saturate or overload the DSP A/D converter stage, the radio will struggle with the signal processing function. Using attenuation will moderate the DSP levels and help improve the signal processing.
5) Tune around the band and look for a few signals to see that all is working ok.
6) Try using a somewhat narrower Bandpass Filter selection. When you reduce the filter bandwidth by half, the noise floor will also drop by half. Assuming your listening to SSB, you may not have too many workable selections as you will need a bandwidth of about 2.4 kHz to recover all the intelligible audio components. (You can narrow it much more for CW operation but a voice signal will require more bandwidth.
7) Experiment with the receiver RF Gain knob. When adjusted correctly it can help improve the signal quality by establishing a RX threshold that improves weak signal readability.
8) You may also have a local noise source that is generating high levels of noise from time to time. This is harder to find and the spectral distribution of such noise sources is usually rather broadband and would be expected to affect more than one band. Consider possible noise sources (plasma TV, LED light bulbs, WALL WARTS). Wall warts or small AC to DC power supplies usually used to run small devices such as recharge batteries or charge your cell phone or cordless screwdriver. These often include a switching stage voltage regulator which can be great noise sources. Try hunting for local noise sources using a small AM transistor radio tuned to a blank frequency on the AM dial.
You stated you added a footswitch, headset and microphone. You always want to be suspicious of any recent changes that you have made to your setup. Try using the handheld mic that came with the radio. You now it works so try the original equipment and see if you still have the problem. Does the Power Out meter level bounce when you speak into the microphone? It should.
1) Verify that you are in SSB mode and have not accidentally selected another mode such as CW or FM mode.
2) Check the Mic gain settings – verify it is not set too low or too high.
3)Try monitoring your signal with another receiver with NO ANTENNA ATTACHED – be careful not to overload or damage that receiver. (Note: a few HTs can actually tune and demodulate your HF signals (my Kenwood TH-F6 can receive HF CW and SSB signals).
Well hopefully, that will give you a couple of things to try. Please share any results you make as that may help others with a similar problem.
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