How to extend antenna from sony undercounter cd player/radio

[Welchs101]

I have a sony under the counter radio and cd player that does not get stations very well.....so we cant really use it as a radio player very well. I was hoping to "extend" the antenna by soldering some wires to the existing antenna to "pick up more stations" if this is even possible.

The sony model number is ICF-CD543RM

I have included some pics of what i believe is the antenna. I was hoping to solder some wires to the existing antenna and run them to the outside of the case and up the wall if possible.

Any suggestions would be welcomed!

Thanks.

[Krankshaft]

Re: How to extend antenna from sony undercounter cd player/radio

That's the ferrite bar antenna for AM it can be upgraded or remotely mounted for better AM reception.

Cheaper radios without antenna jacks or a little FM antenna wire extending outside the case use the power cord for FM reception try redirecting the cord in a straight line and see if the signal improves.

What types of signals are you trying to improve AM or FM?

[Welchs101]

Re: How to extend antenna from sony undercounter cd player/radio

mainly FM

[Welchs101]

Re: How to extend antenna from sony undercounter cd player/radio

given the location of the wall outlet (and my wife not wanting a power cord running up the wall) is there someway to tie-in to the antenna without also tying into the pwer cor to increase reception?

[Welchs101]

Re: How to extend antenna from sony undercounter cd player/radio

thanks for the ideas.......i am thinking how to do that and not make it look "messy"

[Krankshaft]

Re: How to extend antenna from sony undercounter cd player/radio

I have a radio in my kitchen and I had to string up a tiny antenna wire around the base of the cabinet with clear tape to get good reception. My radio had an external coax antenna jack though.

In your position the simplest option if the stock cord isn't enough is to use an extension cord this will extend the antenna and it can be hidden under the cabinet in a coil to improve reception.

The other option would be to find the input FM RF stage and solder a small gauge wire to it route it outside the case and coil that.

[Welchs101]

Re: How to extend antenna from sony undercounter cd player/radio

how do i find the "input FM stage".........thanks for the suggestions.

[Th3_uN1Qu3]

Re: How to extend antenna from sony undercounter cd player/radio

Look for a spot marked ANT. Even if it doesn't have an actual antenna it's VERY likely that the point is marked. If you don't find it, google the markings you find on any chips the board has and you'll find some datasheets. One of them is going to be the tuner IC - find the pin named FM_ANT and solder a wire there.

[Welchs101]

Re: How to extend antenna from sony undercounter cd player/radio

i looked at the printed circuit board again..........i am also enclosing some pics.

I only found one thing that referenced "FM" and i show this in one of the pics..........is the "white square" thing the antenna? If so what do i solder to?

[Th3_uN1Qu3]

Re: How to extend antenna from sony undercounter cd player/radio

I have no idea what that is from that angle, but it probably doesn't have to do with the antenna. I've seen those parts before... but it escapes me right now what they are.

[Scenic]

Re: How to extend antenna from sony undercounter cd player/radio

any surface mount ICs on the solder side of the PCB? (datasheets *hint hint*)

[jack3756]

Re: How to extend antenna from sony undercounter cd player/radio

Hi, I know its few years late, but if anyone in this thread still interested (or come across this post by accident) I may have the answer to this question. BTW the same answer may apply to ANY FM radios where power cord is used as antenna. But some background first;
I have the same exact radio, and I also had poor FM reception.
You see the idiot technical writer (who thinks he knows all about consumer-level electronics) who wrote the installation manual, and the junior engineering project manager (who also thinks he knows all about consumer-level electronics) who was making decisions about industrial design of this radio decided that its a good idea to design the power cord storage hooks built-in the back of the housing of the radio. Normally it is a good idea, as no one likes power cords draping all over their kitchen counters. Except when the power cord also serves as FM antenna. Coiling the power cord at the back of the radio actually slightly amplifies any noise which may be present in your 110V kitchen supply wiring, and at the same time attenuates (reduces the level) of any signal which may be received from local FM radio stations.
The result is lower signal levels in receiving antenna, and higher noise levels, also known as poor signal to noise ratio.
This usually leads to poor reception quality, which manifests itself in lots of noise picked up by many stations when the power cord's orientation is not absolutely optimal.
The simple (and I've found best) technical solution is to uncoil the power cord, string it up the wall next to the radio as far up as you can and secure it in that position by a wall-mounted device, such as plastic kitchen towel/glove hook. That, of course is only possible if your radio is mounted close to the edge of the cabinet, where you have access to the cabinet's side or the wall. While the signal reception with this method is usually improved, the aesthetics of your installation is usually less than desired, which often is mentioned by the installer's wife, girlfriend, significant other, e.t.c.
If you are, at this point, happy with the reception quality, but would like to also correct the appearance as much as possible, the solution may be plastic wire mold sold at many home improvement stores. Something that is usually can be cut to the length and attached to a wall adhesive tape, screws e.t.c. and the section of radio's power cord is hidden inside of it.
If reception quality has not improved, that usually means that the signal from the radio stations is too weak, either as a result of station being too far away, too many obstructions between your radio and the radio station's tower (many concrete buildings have steel reinforcement in the walls, which attenuates the signal), or there is too many sources of electrical/electromagnetic noise nearby.
In either case to get better reception you will need better antenna. The problem is that with radios, which use its power cord as antenna's the power cord is all there is. Well, not really, but to improve on the receiving abilities of the factory power cords some technical skills are required, which in most cases are beyond people which are not knowledgeable in electronics.
If you are however, knowledgeable enough, here is what I did, and what you can do as well.
There is a point in the Printed Circuit Board of a radio where signal from the output of the 110V step-down transformer is picked up through a capacitor (C921, 100pF) and is fed into an FM input of a Radio ASIC (Application Specific Integrated Circuit). In my case the radio is SONY ICF-CD543RM, and the IC's Designator is IC1 (CXA1960Q). I removed the C921, in order to disconnect the FM antenna iput from the power cord. I then got a section of AWG26 stranded wire with white PVC insulation about 6.3 feet long, drilled a small hole at the back of the lower housing of the radio very close to where the location of the C921 was, fed the wire through the hole, stripped off about 1/8" of insulation and soldered it to the trace on the PCB where FM signal is suppose to be conducted to the IC1.
I then tested the radio reception to ensure I didn't mess anything up, reassembled the radio and mounted it back under the cabinet. The new wire antenna I created was strung up vertically up the wall, and since its very thin and white, its barely visible. I have had excellent reception ever since.
Here is he reason for 6.3 feet wire length; antennas ability to pickup electromagnetic waves are directly related the length of the wave. The length of the wave is inversely proportional to the frequency of the signal being picked up (1/f). The FM frequency range is centered at 98 MHz. Based on experimentally determined highest gain antennas are 5/8 of the wavelength the optimal length of the wire is 37.66 inches, or whole multiples of it (in my case 37.66" x 2).
There you have it.

[JMcAward]

Re: How to extend antenna from sony undercounter cd player/radio

@ Jack3756,
You're my hero. I have tried a bunch of things on the way to throwing out this vintage 2005 radio (plays CDs fine, receives practically nothing.) I even built an RF pre-amp inside (powered from the Sony power supply & wired to the chip FM antenna input) which was an improvement - but I hadn't thought through the (alleged) connection to the line cord. Thanks to you I located and lifted C921, wired up an external antenna, and saw a marked an improvement.

Today's project started with my weekly frustration that I can't listen to Car Talk on NPR in my kitchen. Now? MUCH better.
Thanks, Jack3756!
Jim

[kc8adu]

Re: How to extend antenna from sony undercounter cd player/radio

hadnt even seen this before now.
i was expecting a scheme to use the line cord as the ant. or a long trace around the perimeter of the board.

[budm]

Re: How to extend antenna from sony undercounter cd player/radio

My old Zenith clock radio uses a small metal u shape clamp on to the power cord, the metal clamp is then connected to the FM antenna terminal, works pretty well in the city, most of the time they just wrap the FM antenna wire around the power cord, very old trick used on table radios.

[redwire]

Re: How to extend antenna from sony undercounter cd player/radio

I think the FM antenna take off is a metal pin just above C19, under the wax, so you can't quite read the pcb.
Be careful not to bend those nearby coils, they are tuned and blobbed with wax.
Small radios like this used to put a few loops of wire around line cord, for the FM antenna.

[skerchner]

Re: How to extend antenna from sony undercounter cd player/radio

I've got the same reception problem and would like to add an antenna. Can anyone provide a photo or more descriptive explanation of where the wire needs to be soldered? I see that some mention C291(I can't locate) and C19(I can locate). Any help would be appreciated.

[redwire]

Re: How to extend antenna from sony undercounter cd player/radio

This is my best guess as to where the factory FM antenna take-off might be...
I would connect a foot long wire or so, and experiment. In the old days it would be a 6" piece of wire wrapped around the AC power cord, as the antenna. Careful not to bend the copper coils. Let us know how it works out.

For the tech types, I think the common-mode chokes filter out the FM so the set has no ground plane and thus weak reception.

[Dfink]

Re: How to extend antenna from sony undercounter cd player/radio

I know this is old. But I just did this mod to my Fiancée's radio. She insisted she needed it mounted under one of the kitchen cabinets in our new house. C921 is on the back side of the board. I know the board looks like it's single sided but there are components on the back. C921 is a surface mount capacitor on the back of the board towards one of the corners.

[C Don 85]

Re: How to extend antenna from sony undercounter cd player/radio

To Jack 3756 - You explained wonderfully
I know this is an old tread but my wife has decided to throw away her under cabinet radio Cd player (Sony CD543rm) because she likes to listen to Rush Limbaugh on FM and the reception was terrible.
Jack, you explained the solution perfectly. I took the radio apart and finally found the capacitor C921 on the back side of the board. It is about the size of a half grain of uncooked rice on the line that comes from the power transformer secondary.
I unsoldered it. I wanted to run an antenna wire from the capacitor but could not get the wire to solder to the capacitor. I gave that up and ran a Teflon coated antenna wire to a 1/8 inch mono phone jack that I installed in a hole I drilled above the vent hole. This kept it out of the way of the power cord wrapping place.
When I put the machine together the reception was so good that I decided against putting an antenna wire in.

Than you again for passing on your knowledge. C Don