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1/8 th antennas for headphone jacks

O

Ozman

anyone know of any 1/8th antennas are around that hook up to a regular stereo headphone jack.
also looking for a 1/8th cable witre antenna preferably amplified by a AA battery or oqivlinent so I can get better rececption on my sangean pocket radio. do any of know af anything out there?

also anyone know of any way to amplify the reception on ipods where you get the ipod radio remote add on
thanks -OZ
 
Usually, the headphone ground is floated relative to the RF ground, and the RF input is connected to the shield of the coax - which is a fancy way to say that the antenna is IN the headphone wire. So any standard headphone will contain the antenna.

Now, if you have some technical skill, you can boost the reception of walkman type radios to an astonishing degree. The RF input to the radio is buffered by a wide band - and lossy - broadband ceramic filter. You can take that filter out, and attach a 31 inch wire directly to the antenna input of the radio. Marginal stations will literally come alive - and the performance of the walkman radios can approach that of good table radio models.
 
I'll look into that I have had fun trying to modify sony d-fj61 models. unfortunately I cannot find where the 3 pin filter (110khz etc..) is to try and narrow the band as well. where might I find the broadband ceramic filter btw why 31 inches? best signal gain... Can I do that in the ipod remote as well because that would make a big difference...

sencondly in the portable sangeans ie 210 300 etc which come with the wire antenna feature when you put it on speaker mode, is their a way to crank up the reception on their radios
thanks for the help so far

rbrucecarter5 said:
Usually, the headphone ground is floated relative to the RF ground, and the RF input is connected to the shield of the coax - which is a fancy way to say that the antenna is IN the headphone wire. So any standard headphone will contain the antenna.

Now, if you have some technical skill, you can boost the reception of walkman type radios to an astonishing degree. The RF input to the radio is buffered by a wide band - and lossy - broadband ceramic filter. You can take that filter out, and attach a 31 inch wire directly to the antenna input of the radio. Marginal stations will literally come alive - and the performance of the walkman radios can approach that of good table radio models.
Click to expand...
 
> unfortunately I cannot find where the 3 pin filter (110khz etc..) is to try and narrow the band as well.

Don't be afraid to carefully disassemble the radio to the point where you have just a PC board - as long as you know how to reverse the procedure you should be fine. If you have a lot of static electricity in your location, doing the work with aluminum foil on your work surface will work as ESD suppression. There should be two ceramic filters. Generally, the IF one should be fairly close to the tuning capacitor. If it is a digital unit, finding the ceramic filter will be even easier, because it may be one of the few leaded components on the board. IF they use a surface mount ceramic filter, unless you are really good with surface mount rework and have a hot air soldering station, I would leave it alone.

> where might I find the broadband ceramic filter

Trace the circuit from the headphone jack - usually the things are dark brown and a little larger than the IF ceramic filters.

> btw why 31 inches? best signal gain...

Supposedly that is close to 1/4 wavelength of FM. I haven't done the math recently, but that is the length of car antennas - before they started hiding them.

> Can I do that in the ipod remote as well because that would make a big difference...

Sure

> sangeans ie 210 300 etc which come with the wire antenna feature when you put it on speaker mode, is their a way to crank up the reception on their radios

I don't know much about Sangean - they have a lot of fans, so good antenna technique, coupled with the narrow ceramic filter trick on FM should help them.

Actually - one of the hottest portables I have come across was one made by "Mary Kate and Ashley" - my daughter bought it - it is a round "boom box" - and just stock it had really good RF performance. At the time, my daughter wanted a medium fringe 88.3 that was jammed by an 88.5 two miles away, so I tore into it, put in the 110k ceramic filter, and just for the heck of it tried an 8 inch ferrite bar on AM and my outdoor antenna on FM. The thing came alive with stations, and I was pleasantly surprised there was little if any overload. Now there was an economical, one IC radio design done right! Hats off to the twins - they must have had some say in the selection of circuitry - and picked a good design. When my daughter outgrows the thing, I'm grabbing it!
 
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