UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - BBC Radio 4 long wave reception problems etc.

G0HZU_JMR · 2nd Feb 2019, 1:42 am

I had a listen mid afternoon (Friday) and the audio was very poor. I quickly set up one of my analysers to capture a few minutes of the transmission either side of the news. On playback I could see that the time pips had visible harmonic distortion out to about the 4th or 5th harmonic. There was also some splatter out beyond the usually sharp cutoff at +/- 5kHz when the news presenter was speaking. The sibilance was also very noticeable. I captured the pips again this evening and the harmonic distortion had virtually gone. The wanted pip tones are something like -15dBc and the 2nd harmonic distortion level is about -55dBc. The transmitter may actually be cleaner than this (when it is healthy) as I think my little active antenna causes a tiny amount of distortion.

When the transmitter is poorly, the distortion terms from the time pips jump up at least 20dB and I can see harmonics out to several kHz.

2nd Feb 2019, 1:42 am	#22
G0HZU_JMR Dekatron Join Date: Sep 2010 Location: Cheltenham, Gloucestershire, UK. Posts: 3,077	Re: BBC Radio 4 198 kHz long wave sibilance. I had a listen mid afternoon (Friday) and the audio was very poor. I quickly set up one of my analysers to capture a few minutes of the transmission either side of the news. On playback I could see that the time pips had visible harmonic distortion out to about the 4th or 5th harmonic. There was also some splatter out beyond the usually sharp cutoff at +/- 5kHz when the news presenter was speaking. The sibilance was also very noticeable. I captured the pips again this evening and the harmonic distortion had virtually gone. The wanted pip tones are something like -15dBc and the 2nd harmonic distortion level is about -55dBc. The transmitter may actually be cleaner than this (when it is healthy) as I think my little active antenna causes a tiny amount of distortion. When the transmitter is poorly, the distortion terms from the time pips jump up at least 20dB and I can see harmonics out to several kHz. __________________ Regards, Jeremy G0HZU Last edited by G0HZU_JMR; 2nd Feb 2019 at 1:47 am.