FM signal strength drops as I move away - UK Vintage Radio Repair and Restoration Discussion Forum

indigo.girl · 20th Dec 2016, 4:30 pm

Hi everyone,
I have a Dynatron SRX24C unit that normally has very good FM signal strength. There is a stereo signal light and meter confirming that. However, today I have found the FM signals are very weak and barely registering 1 on the signal meter (I can normally get around 4). I switched off and tried again later and signal strength is OK again but seems very sensitive to where I stand. As I stand nearby to tune its OK but as I walk away signal reduces to almost nothing. I know that the human body can deflect and shatter FM signals either increasing or decreasing the signal that reaches the antenna but I've never seen it this pronounced before. Are there factors like temperature, weather etc that can be exacerbating this effect today or have I developed a new fault somewhere?

Thanks,
Nicola

toshiba tony · 20th Dec 2016, 4:56 pm

Forgive me for mentioning the obvious, is the FM aerial satisfactory, it seems your body is doing a better job than the aerial.

emeritus · 20th Dec 2016, 5:12 pm

Have you moved anything metal into the vicinity? My bedside transistor reception suddenly dropped off last week when my wife left a metal step ladder in the bedroom a few feet from the radio, and improved when I removed it. Reception is not helped by the presence of a coke breeze block interior wall that is an excellent RF absorber, between the radio and the transmitter.

indigo.girl · 20th Dec 2016, 5:26 pm

I think you've hit the nail on the head. I have in fact moved a metal flight case into the room and a metal framed bench. It's not right next to the radio but clearly enough to disrupt things. I've removed them and now my radio is working perfectly again. Thanks - a great result

Sideband · 20th Dec 2016, 8:23 pm

Your aerial needs attention! I suspect it is of the indoor variety and as such is subject to reflections from objects. If it's just a simple 'throw-out' single wire type, you might consider a slightly better 'tape' aerial if you are restricted to an indoor type aerial. Better still consider an outside type if possible....with one exception...avoid one of those 'halo' aerials like the plague. If possible, invest in a proper chimney/mast-mounted FM dipole with proper directional properties.

20th Dec 2016, 4:30 pm	#1
indigo.girl Retired Dormant Member Join Date: Apr 2016 Location: Loughborough, Leicestershire, UK. Posts: 754	FM signal strength drops as I move away Hi everyone, I have a Dynatron SRX24C unit that normally has very good FM signal strength. There is a stereo signal light and meter confirming that. However, today I have found the FM signals are very weak and barely registering 1 on the signal meter (I can normally get around 4). I switched off and tried again later and signal strength is OK again but seems very sensitive to where I stand. As I stand nearby to tune its OK but as I walk away signal reduces to almost nothing. I know that the human body can deflect and shatter FM signals either increasing or decreasing the signal that reaches the antenna but I've never seen it this pronounced before. Are there factors like temperature, weather etc that can be exacerbating this effect today or have I developed a new fault somewhere? Thanks, Nicola

20th Dec 2016, 4:56 pm	#2
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: FM signal strength drops as I move away Forgive me for mentioning the obvious, is the FM aerial satisfactory, it seems your body is doing a better job than the aerial.

20th Dec 2016, 5:12 pm	#3
emeritus Dekatron Join Date: Jan 2012 Location: Brentwood, Essex, UK. Posts: 5,339	Re: FM signal strength drops as I move away Have you moved anything metal into the vicinity? My bedside transistor reception suddenly dropped off last week when my wife left a metal step ladder in the bedroom a few feet from the radio, and improved when I removed it. Reception is not helped by the presence of a coke breeze block interior wall that is an excellent RF absorber, between the radio and the transmitter.

20th Dec 2016, 5:26 pm	#4
indigo.girl Retired Dormant Member Join Date: Apr 2016 Location: Loughborough, Leicestershire, UK. Posts: 754	Re: FM signal strength drops as I move away I think you've hit the nail on the head. I have in fact moved a metal flight case into the room and a metal framed bench. It's not right next to the radio but clearly enough to disrupt things. I've removed them and now my radio is working perfectly again. Thanks - a great result

20th Dec 2016, 8:23 pm	#5
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,571	Re: FM signal strength drops as I move away Your aerial needs attention! I suspect it is of the indoor variety and as such is subject to reflections from objects. If it's just a simple 'throw-out' single wire type, you might consider a slightly better 'tape' aerial if you are restricted to an indoor type aerial. Better still consider an outside type if possible....with one exception...avoid one of those 'halo' aerials like the plague. If possible, invest in a proper chimney/mast-mounted FM dipole with proper directional properties. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....