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andrewgm · 15th Jun 2019, 11:16 am

Hello everyone - new to the forum and just joined.
My electronics experience and knowledge is quite low level compared to the majority or members here so apologies in advance !

My problem is I have a beautiful and very good Signal R535 ( as it's called ) dedicated to monitoring of Civil and Military Airband frequencies. The beauty of it lies in its simplicity of function and layout internally. It's not riddled with dials, knobs and mysterious displays that look like it belongs in a plane itself.
Anyway its performance is still sensational compared even to some more modern offerings.

Getting to the point then. It runs on a quite normal 12V DC feed and inside the case is a 1000uf 16v electrolytic and UN4002 diode across the +/ve and -/ve - the schematic supports this.

I now regrettably decided to change the cap to a low ESR Panasonic FC and UF4002 diode while I was in. It all went well, I don't remember snapping anything, something falling out unexpectedly, dropping any solder inside or any moments when I thought "Oh God"

I put it all back together, powered her up and the display was fine, the functions were fine, squelch functioning, noise was the same - no problems.
Except I've got FM radio transmissions all over it and bizarrely no Airband comms at all.

I put another radio in its place and it worked fine. I even put back the old bits and of course that didn't help.

I'm not the kid waving a hand held round in the air at an airport but am quite serious about the hobby as I enjoy it very much. My system comprises of a copper J pole at height and cut for civil Airband frequencies, use LMR400 coax at under 10 metres in length, have a dedicated low noise power supply, passband filter made for airband listening and have an RF filter on the 12v power supply line to the R535 itself. Pilot transmissions are like DAB radio and the tower transmission is first class.

I say is......it was !! The FM breakthrough strength at the moment gets through the passband filter it seems !

So, anyone any ideas on what on earth I've done to it!? I've done something for sure but I'm just not clever enough.

Many thanks, Andrew.

15th Jun 2019, 11:16 am	#1
andrewgm Retired Dormant Member Join Date: Jun 2019 Location: Gateshead, Tyne and Wear, UK. Posts: 9	Signal Communications Corp R535 Receiver Hello everyone - new to the forum and just joined. My electronics experience and knowledge is quite low level compared to the majority or members here so apologies in advance ! My problem is I have a beautiful and very good Signal R535 ( as it's called ) dedicated to monitoring of Civil and Military Airband frequencies. The beauty of it lies in its simplicity of function and layout internally. It's not riddled with dials, knobs and mysterious displays that look like it belongs in a plane itself. Anyway its performance is still sensational compared even to some more modern offerings. Getting to the point then. It runs on a quite normal 12V DC feed and inside the case is a 1000uf 16v electrolytic and UN4002 diode across the +/ve and -/ve - the schematic supports this. I now regrettably decided to change the cap to a low ESR Panasonic FC and UF4002 diode while I was in. It all went well, I don't remember snapping anything, something falling out unexpectedly, dropping any solder inside or any moments when I thought "Oh God" I put it all back together, powered her up and the display was fine, the functions were fine, squelch functioning, noise was the same - no problems. Except I've got FM radio transmissions all over it and bizarrely no Airband comms at all. I put another radio in its place and it worked fine. I even put back the old bits and of course that didn't help. I'm not the kid waving a hand held round in the air at an airport but am quite serious about the hobby as I enjoy it very much. My system comprises of a copper J pole at height and cut for civil Airband frequencies, use LMR400 coax at under 10 metres in length, have a dedicated low noise power supply, passband filter made for airband listening and have an RF filter on the 12v power supply line to the R535 itself. Pilot transmissions are like DAB radio and the tower transmission is first class. I say is......it was !! The FM breakthrough strength at the moment gets through the passband filter it seems ! So, anyone any ideas on what on earth I've done to it!? I've done something for sure but I'm just not clever enough. Many thanks, Andrew.