While on vacation at my hometown during the National Day holiday, I brought along the JPC-7 with a handheld V-antenna and paired it with an FT-891 for the first time, setting it up on the rooftop of my apartment building.
During the day, the background noise was relatively good, around S6-S7. After initial setup, I successfully established SSB communication with several other stations. However, as soon as it got dark, the background noise increased to S9. I suspect that the continuous operation of LED streetlights on the streets below and in front of the building is a major factor. My apartment is only on the 5th floor, which may not be high enough.
However, when I switched to the non-harmonic wave band, I found that the noise in other bands was not significant; it only appeared in S3 and S4, making it very easy to receive distant QSOs.
Once the 40-meter harmonic and standing wave were properly tuned, the S9 noise level was directly at 7.070. However, switching to the 20-meter band, although not a harmonic point for standing waves, resulted in very low S3-S4 noise levels, making it easy to receive signals. However, it could not be used for transmitting.
In summary, the key is to properly tune that specific harmonic resonance. When this resonance is well-tuned, the noise floor in that particular frequency band will be low, while the noise floors in other non-resonant frequency bands will be higher. Copy and save the ideal settings.
Is this normal?
When I'm feeling unwell during a holiday, I go to the temple to seek medical advice and remedies.
Thank you in advance.
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